Tags

Dynamic USB devices, revamped webassembly port, openamp, tls, vfs modules

This release of MicroPython adds support for dynamic USB devices defined in
Python, adds new `openamp`, `tls` and `vfs` modules, completely revamps the
webassembly port to add proxying between JavaScript and Python, and
implements significant code size optimisations for frozen modules.  There
are also many other enhancements and bug fixes.  Keep reading for a more
detailed summary of the main changes.

After a lot of design, development and testing, MicroPython now has full
support for user-defined USB devices.  The interface is via a new
`machine.USBDevice` class, and this allows the user to specify the USB
descriptors and implement Python callbacks for USB endpoint transfers.
With this, any USB device can be implemented in pure Python.  While the
`machine.USBDevice` interface is low-level and complete, there is a
higher-level USB library in `micropython-lib` that allows easier
implementation of devices, with examples for keyboard, mouse, MIDI and
serial CDC.  This feature is currently available on rp2 and samd ports, and
other ports will follow in the future.

Support for the OpenAMP (asymmetric multiprocessing) protocol has been
added through the new `openamp` module.  This allows MicroPython to control
other CPU cores in the system, to load and start processes and communicate
with them through endpoints.  This feature is currently available on the
mimxrt and stm32 ports.

Two other new modules have been added: `vfs` and `tls`.  The `vfs` module
contains all VFS (virtual filesystem) related functions and classes, such
as `mount`, `umount` and `VfsFat`.  These were originally in the `os`
module but having them there is not compatible with CPython, so they have
been moved to their own dedicated module.  They still exist in the `os`
module for now but will eventually be removed from there, so it's
recommended to start using the `vfs` module from now on.  Similarly the new
`tls` module is an evolution of the `ssl` module, whereby all the existing
functionality in `ssl` has been moved to the `tls` module.  This is done
because MicroPython's SSL interface is becoming increasingly different to
CPython's and moving this SSL/TLS functionality to a new `tls` module gives
it room to grow and obtain new features that are useful for embedded
applications.  And compatibility with normal Python is still retained via a
pure Python implementation of the `ssl` module.  One new feature in the new
`tls` module is the ability to register a certificate verification
callback.

Other additions include more methods on the `deque` object so it is
doubly-ended and supports iteration, and support for half-float 'e' format
in `struct.pack`/`struct.unpack`.  Dynamic native modules have had some
additional runtime methods exposed, and the .mpy sub-version has been
increased from v6.2 to v6.3 (native code in .mpy files will need to be
recompiled, but bytecode does not and is still compatible).

There has also been significant code size optimisations for frozen modules.
A new internal `mp_proto_fun_t` type has been defined which allows the
common case of bytecode functions (as opposed to native code) to be stored
in frozen code without any additional overhead of the `mp_raw_code_t`
descriptor structure.  All firmware builds using frozen modules will see a
significant decrease in size.  Code size has also improved further for very
small targets by adding an option to remove the qstr hash bytes.

Internally in the source code the "STATIC" macro definition has been
removed.  Code should now just use "static" instead.  If you have C/C++
code that uses "STATIC" then either replace it with "static", or provide
your own #define to define "STATIC" as "static".  See commit
decf8e6a8bb940d5829ca3296790631fcece7b21 for details.

Mbedtls has been updated to version 3.5.1.  And network interface
constants, such as `IF_STA` and `SEC_WPA2`, have now been consolidated
across ports so they all live at the `WLAN` class level, for example
`network.WLAN.SEC_WPA2` (existing constants at the `network` module level
have been retained for backwards compatibility, but the new ones should be
preferred from now on).

The esp32 port has seen some important bug fixes in the BLE component, to
deinitialise without crashing, and increase the BLE task stack size.  This
port also uses the new I2S IDF driver, and supports IDF 5.0.5 and 5.2.
There is support to enter the bootloader via `machine.bootloader()` and a
new `esp32.mcu_temperature()`, for ESP32-C3/S2/S3 devices.

The rp2 port has added the new `machine.USBDevice` dynamic USB driver, and
has had firmware performance optimisations applied to critical parts of the
runtime and VM, giving about a 10% performance boost.  There is now direct
memory access to PIO and SPI FIFOs via proxy arrays, and bugs have been
fixed with threads, lightsleep and UART IRQ latency.

The stm32 port has integrated support for the new `openamp` module, which
is enabled on all Arduino boards.  And firmware for Arduino boards now
freeze in additional Arduino-specific library code.  There have been fixes
for internal flash writes on STM32H5 and STM32H7 MCUs (bank selection and
flashing of the last word in a buffer), an important fix to a SPI DMA
caching bug, an I2C clock enable fix for I2C4 on STM32F7 MCUs, and a fix
for the FDCAN source clock frequency on STM32G4 MCUs.  Mboot has added
support for a new raw filesystem, to allow simpler and more robust firmware
updates.

The webassembly port has seen a significant overhaul in its structure, and
is now built as a JavaScript .mjs module that exports a user-friendly
JavaScript-level API which is inspired by the API provided by Pyodide
(which is a version of CPython that runs in the browser).  This change is
motivated by the need to use MicroPython as an engine within Pyscript,
which is a platform for Python in the browser.  New features in the
webassembly port include proxying of objects between Python and JavaScript,
a `js` module to interface with the JavaScript namespace, a `jsffi` module
for miscellaneous proxy helpers, top-level async code, JavaScript driven
asyncio support, automatic growing of the Python heap, integration of
JavaScript and Python finalisation for global memory management, more
`time` module functions, and support for build variants (following the unix
port).

The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):

       bare-arm:   -220  -0.383%
    minimal x86:   -341  -0.184%
       unix x64: +20168  +2.527%
          stm32:  -1692  -0.430%
         cc3200:   +256  +0.139%
        esp8266:  -8880  -1.260%
          esp32:  -3328  -0.194%
         mimxrt:   -408  -0.112%
     renesas-ra:   -464  -0.074%
            nrf:   -640  -0.341%
            rp2:  +5380  +1.626%
           samd:  +3224  +1.229%

The leading causes of these changes in code size are:
- bare-arm, minimal: disabling qstr hashing
- unix: updating mbedtls to version 3.5.1
- stm32: optimising size of frozen modules
- cc3200: addition of new `vfs` module, and bug fixes in the VM and array
  type
- esp8266: disabling unused `MICROPY_DEBUG_PRINTERS` and optimising frozen
  modules
- esp32, mimxrt, renesas-ra, nrf: optimising frozen modules
- rp2: addition of `machine.USBDevice`, enabling -O2 optimisations
- samd: addition of `machine.USBDevice`

Performance is effectively unchanged since the previous release on all
ports, except the rp2 port which sees a performance improvement of roughly
10%.

Thanks to everyone who contributed to this release: Amirreza Hamzavi,
Andrew Leech, Angus Gratton, Brian Pugh, Carlosgg, Christian Walther,
Damien George, Daniël van de Giessen, darc, Dash Peters, David Lechner,
Felix Dörre, iabdalkader, IhorNehrutsa, Iksas, J. Neuschäfer, Jared
Hancock, Jim Lipsey, Jim Mussared, Jochen Sprickerhof, Joey232, Jos
Verlinde, Kwabena W. Agyeman, Maarten van der Schrieck, Matt Trentini,
Matthias Urlichs, Michiel W. Beijen, MikeTeachman, Nicko van Someren,
Olivier Lenoir, Phil Howard, Rick Sorensen, robert-hh, Sebastian Romero,
Simon Wood, Stanislav Ponomarev, stijn, Takeo Takahashi, Trent Piepho,
Trent Warlaven, Vonasmic, YAMAMOTO Takashi, Yoctopuce.

MicroPython is a global Open Source project, and contributions were made
from the following timezones: -0800, -0700, -0600, -0500, -0300, +0000,
+0100, +0200, +0330, +0400, +0900, +1000, +1100.

The work done in this release was funded in part through GitHub Sponsors,
and in part by George Robotics, Espressif, Anaconda, Arduino, LEGO
Education, OpenMV and Planet Innovation.

What follows is a detailed list of all changes, generated from the git
commit history, and organised into sections.

Main components
===============

all:
- fix "reuse" and "overridden" spelling mistakes
- update bindings, ports and tests for mbedtls v3.5.1
- use mp_obj_malloc_with_finaliser everywhere it's applicable
- remove the "STATIC" macro and just use "static" instead
- prune trailing whitespace
- update extmod, ports, examples to build with new berkeley-db lib
- add pre-commit hook for codespell
- update copyright year range to include 2024
- ISSUE_TEMPLATE: convert issue templates to forms

py core:
- py.mk: remove extra build dir created for frozen_content
- qstr: add support for MICROPY_QSTR_BYTES_IN_HASH=0
- mpconfig: disable qstr hashing at minimum feature level
- builtinimport: simplify calls to stat_path()
- compile: fix potential Py-stack overflow in try-finally with return
- emitglue: reorder and resize members of mp_raw_code_t
- emitglue: provide a truncated mp_raw_code_t for non-asm code
- emitglue: simplify mp_raw_code_t's kind and scope_flags members
- emitglue: introduce mp_proto_fun_t as a more general mp_raw_code_t
- emitglue: include fun_data_len in mp_raw_code_t only when saving
- makeversionhdr.py: reinstate MICROPY_GIT_HASH in mpversion.h
- obj: change sizeof to offsetof in mp_obj_malloc_var macro
- obj: introduce mp_obj_malloc_with_finaliser to allocate and set type
- misc: remove m_new_obj[_var]_with_finaliser macros
- objfun: make mp_obj_new_fun_native/mp_obj_new_fun_asm static-inline
- objfun: split viper fun type out to separate mp_type_fun_viper type
- emitnative: simplify layout and loading of native function prelude
- objfun: support __name__ on native functions and generators
- objfun: inline mp_obj_code_get_name() into mp_obj_fun_get_name()
- emitglue: remove n_pos_args from DEBUG_printf
- builtinevex: fix setting globals for native functions in compile()
- compile: remove TODO about name mangling
- emitglue: make mp_emit_glue_assign_native's fun_data arg a const ptr
- mpconfig: change the default enable level for the vfs module
- emitbc: remove call to adjust Python stack by 0 entries
- mpstate: don't declare mp_thread_get_state()
- modthread: move thread state initialisation to shared function
- emitglue: add explicit cast of proto_fun to uint8_t pointer
- objstr: add a macro to define a bytes object at compile time
- stream: add mp_stream_seek() helper function
- stream: factor stream implementations
- objdeque: expand implementation to be doubly-ended and support iter
- asm: add ASM_NOT_REG and ASM_NEG_REG macros for unary ops
- asmxtensa: optimise asm_xtensa_mov_reg_i32_optimised() for tiny ints
- emitnative: implement viper unary ops positive, negative and invert
- binary: support half-float 'e' format in struct pack/unpack
- parse: zero out dangling parse tree pointer to fix potential GC leak
- compile: add option to allow compiling top-level await
- nlr: add "memory" to asm clobbers list in nlr_jump
- makeqstrdata.py: ensure that scope names get low qstr values
- dynruntime: add mp_binary_get_size/get_val_array/set_val_array
- persistentcode: bump .mpy sub-version to 6.3
- objfun: fix C++ compatibility with casting in inline functions
- obj: fix initialiser order in MP_DEFINE_CONST_OBJ_TYPE_NARGS_ macros
- objarray: fix use-after-free if extending a bytearray from itself
- nlrthumb: make non-Thumb2 long-jump workaround opt-in
- dynruntime: add mp_obj_exception_init function to create C exception
- dynruntime: export mp_load_method_maybe and mp_arg_parse_all* funcs

extmod:
- extmod.mk: disable uninitialized warnings in kf_rem_pio2.c
- asyncio: support gather of tasks that finish early
- modssl_mbedtls: fix cipher iteration in SSLContext.get_ciphers
- modssl_axtls: add SSLContext.load_cert_chain()
- modtls: move the native ssl module to tls
- modtls_mbedtls: implement cert verification callback for mbedtls
- modvfs: add new "vfs" module with mount/umount and Vfs classes
- btstack: reset pending_value_handle before calling write-done cb
- btstack: reset pending_value_handle before calling read-done cb
- modrandom: add integer type casts where appropriate
- modlwip: support IPv6
- network_wiznet5k: adjust IP types for IPv6
- vfs_posix_file: ensure file object has safe default fd
- modmachine: remove MICROPY_PY_MACHINE guard from header
- modwebsocket: fix websocket to send correct close frame
- modlwip: add back support for empty IP addresses
- asyncio: make current_task raise exception when there is no task
- nimble: override configuration options set in nimble_port_init
- nimble: enable key distribution to support bonding
- network_ninaw10: activate the NIC on demand
- network_ninaw10: set the proper security mode if none provided
- network_ninaw10: fix error messages
- modmachine: add MICROPY_PY_MACHINE_SIGNAL configuration option
- modmachine: add MICROPY_PY_MACHINE_MEMX configuration option
- modmachine: add MICROPY_PY_MACHINE_RESET configuration option
- nimble: check for active before setting address mode
- machine_usb_device: add support for Python USB devices
- libmetal: add MicroPython platform for libmetal
- modopenamp: add new OpenAMP module
- modopenamp_remoteproc: add new OpenAMP RemoteProc class
- os_dupterm: handle exception properly when it occurs in parallel
- modnetwork: implement IPv6 API to set and get NIC configuration
- network_wiznet5k: properly enable interrupt signal on w5100s
- add interface and security constants at WLAN class level
- modtls_axtls: add verify_mode and CERT_NONE constant
- modopenamp: set a default log handler for ports
- modopenamp: use metal logging functions exclusively
- modasyncio: make mp_asyncio_context variable public
- network_wiznet5k: properly enable socket buffers for W5100(S)
- modlwip: use Nagle algorithm and add support for TCP_NODELAY
- modos: only sync FAT filesystems using disk_ioctl

shared:
- timeutils: remove useless void-return
- tinyusb: don't disconnect on soft reset unless USB was active
- tinyusb: update some code comments for runtime USB
- tinyusb: increase default string descr max length to 40 chars
- tinyusb: fix dynamic USB control callbacks for wLength==0
- tinyusb: stall the CDC IN endpoint while disconnecting

drivers:
- dht: only build DHT driver if MICROPY_PY_MACHINE_PULSE enabled
- memory: add IS25LPWP064D chip to list of external flash devices

mpy-cross: no changes specific to this component/port

lib:
- cmsis: update to CMSIS 5.9.0
- mbedtls: update to mbedtls v3.5.1
- mbedtls_errors: update error list for latest mbedtls
- micropython-lib: update submodule to latest
- cyw43-driver: update driver to latest version v1.0.3
- open-amp: add OpenAMP submodule
- libmetal: add libmetal submodule
- berkeley-db-1.xx: update submodule URL and version
- arduino-lib: add Arduino's external library

Support components
==================

docs:
- samd/pinout: update pinout docs with fixed pin assignment
- develop/porting: fix argument type of mp_lexer_new_from_file()
- add note about position-only arguments in CPython vs MicroPython
- library/ssl: change wrap_socket args keyfile/certfile to key/cert
- library: move vfs functions and classes from os to vfs module docs
- reference/micropython2_migration.rst: add info about os and vfs
- use vfs module instead of os
- library/sys.rst: document implementation.version.releaselevel
- library/bluetooth: add note that ESP32 supports pairing/bonding
- library/openamp: document the new openamp module
- library/collections: update deque docs to describe new features
- library/rp2.DMA: add documentation for rp2 DMA support
- library/machine.RTC: add docs for RTC.memory() method
- reference/mpyfiles: document change in .mpy sub-version
- develop/optimizations: fix typo identified in issue 14391
- esp32/quickref: add note about different ESP32 varieties
- library/machine.USBDevice: update note about packages in mp-lib
- reference: document how to mip install packages from GitLab
- library/asyncio: document that ThreadSafeFlag now works on unix
- update copyright year range to include 2024

examples:
- embedding: add -fno-common to the sample compiler flags
- natmod/framebuf: enable FrameBuffer.poly method
- usb: add a very simple USBDevice example with host
- usb: add a USBDevice example implementing the DFU protocol
- network: rename SSL examples to start with https
- network: add example of HTTPS client using non-blocking socket
- usb: add README that points out the alternative usb modules
- natmod/features4: create custom FactorialError as exc example
- natmod/btree: make btree.open use mp_arg_parse_all for kwargs

tests:
- run-tests.py: remove machine_mem.py test from skip list
- thread: adjust thread tests so most are able to run on rp2 port
- thread: add a test for accuracy of sleep within a thread
- run-multitests.py: change to dir of test script when running it
- multi_net: generate smaller certs with 2048-bit RSA
- run-tests.py: add an option for running only the failed tests
- run-tests.py: remove unneeded argument from run_feature_check()
- run-tests.py: make repl test detection more correct
- run-tests.py: fix path-based special test detection
- extmod/machine_uart_tx.py: add a test for timing of UART.flush()
- move port-specific test directories into tests/ports/ directory
- ports/rp2: add rp2-specific tests with a test for rp2.DMA
- extmod/machine_i2s_rate.py: test multiple I2S instances
- extmod/asyncio_wait_task.py: add test for raise and delayed wait
- extmod: remove asyncio .exp files that match CPython output
- extmod/framebuf_polygon.py: replace sys.stdout.write with print
- ports/rp2/rp2_dma.py: tweak test to be more reliable
- use vfs module instead of os
- multi_bluetooth/ble_irq_calls.py: enhance test to test recursion
- ports/unix: add coverage test for frozen functions and generators
- cpydiff: add new CPy diff test for class name mangling
- multi_bluetooth: move ble_deepsleep to stress_deepsleep_reconnect
- basics: split MicroPython-specific deque tests to separate file
- float/float_struct_e.py: add specific test for struct 'e' type
- run-tests.py: support running webassembly tests via node
- ports/webassembly: add webassembly JS tests
- net_inet: add simpler tls sites test, and skip existing on axtls
- cpydiff: add a note about risk of resizing memoryview targets
- micropython/import_mpy_invalid.py: skip if target cant import mpy
- run-natmodtests.py: fix search for supported native tests
- extmod: fix regex strings to be of r"" type
- extmod: add .exp test files for asyncio.get_event_loop tests
- basics: split out generator.throw tests that pass multiple args
- net_hosted/ssl_verify_callback.py: make exp match actual output
- net_inet/tls_text_errors.py: tweak test for newer CPython version
- float: use "not" instead of ~ to invert bool value
- basics: add .exp file for slice_op test
- basics: move str/bytes tests that give SyntaxWarning to sep file

tools:
- gen-changelog.sh: exclude "-preview" tags from generated log
- mpremote: reduce dependency on importlib_metadata
- manifestfile.py: change library search to use a list of paths
- mpy-tool.py: fix static qstrs when freezing without qstr header
- mpy-tool.py: skip generating frozen mp_raw_code_t when possible
- manifestfile.py: add --unix-ffi option
- ci.sh: add Arduino GIGA to stm32 CI build
- mpy-tool.py: fix merging of more than 128 mpy files
- ci.sh: update webassembly CI tests
- manifestfile.py: fix freeze() when script is an empty iterable
- mpremote: add support to mip install from GitLab
- ci.sh: simplify selection of natmod tests to run

CI:
- workflows: bump actions/cache from 3 to 4
- workflows: run mimxrt and rp2 CI with space in repository path
- workflows: move Windows CI from AppVeyor to GitHub Actions
- workflows: bump setup-msbuild, setup-python, checkout versions
- workflows: initialise micropython-lib submodule for windows CI
- workflows: move codespell to a GitHub workflow, version it
- workflows: add comments where tool versions need to be in sync
- workflows: standardise formatting of ruff.yml
- workflows: add Biome workflow for JavaScript formatting/linting
- workflows: update coverage workflow to codecov-action@v4
- workflows: run code size workflow on shared or port code changes

The ports
=========

all ports:
- move MICROPY_PY_LWIP_ENTER/REENTER/EXIT defns to mphalport.h
- move MICROPY_INTERNAL_WFE definition to mphalport.h
- fix handling of paths containing spaces in Makefiles
- add LED pin aliases for all Arduino boards
- use vfs module instead of os
- on cold boot, enable USB after boot.py completes
- don't include mpthread.h in mpthreadport.h

bare-arm port: no changes specific to this component/port

cc3200 port: no changes specific to this component/port

embed port:
- fix alloca include for FreeBSD and NetBSD
- improve stack top estimation

esp8266 port:
- boards/ESP8266_GENERIC: disable MICROPY_DEBUG_PRINTERS
- Makefile: add support for C++ user C modules
- network_wlan: add interface and security WLAN constants

esp32 port:
- modsocket: use all supplied arguments to socket.getaddrinfo()
- boards/UM_FEATHERS3: use read_uv() for accurate battery voltage
- network_ppp: make PPP support optional
- mpnimbleport: release the GIL while doing NimBLE port deinit
- increase NimBLE task stack size and overflow detection headroom
- machine_i2c: fix build warnings when I2C is disabled
- machine_hw_spi: combine argument parsing for constructor and init
- boards: add missing named digital pins for Arduino Nano ESP32
- machine_i2s: integrate new I2S IDF driver
- add support for IDF version v5.0.5
- add support for IDF version v5.2
- add IDF-version-specific sdkconfig
- mpconfigport: don't hang when machine.bootloader isn't supported
- modmachine: support bootloader on ESP32-S2/S3/C2/C3
- network_lan: add a separate argument to set PHY power pin
- machine_uart: always configure timeout_char setting in init()
- boards/ESP32_GENERIC_S3: add 4MiB partitioning board variant
- workaround IDF issue placing ISR ringbuf functions in IRAM
- main: check if main GC heap allocation failed
- network_wlan: add interface and security WLAN constants
- modesp32: add mcu_temperature() function for C3/S2/S3 devices
- panichandler: print support information on panic
- add support for TCP_NODELAY

mimxrt port:
- mphalport: remove redundant NVIC/IRQ defines
- mpbthciport: add missing extmod/modmachine.h header
- boards: fix __VECTOR_TABLE link issue with CMSIS 5.9.0
- modmachine: fix deepsleep wakeup pin ifdef
- fix header include guard names
- mpconfigport: enable cryptolib and hashlib md5
- define the MICROPY_HW_ENABLE_USBDEV macro
- set the security mode for the default WiFi AP
- add support for OpenAMP

minimal port:
- allow compiling on macOS
- use printf instead of echo -e

nrf port:
- modules/os/microbitfs: sweep the filesystem if any free chunk found
- fix _start() build issue with CMSIS 5.9.0
- boards: add named pins for Arduino Nano 33 BLE
- boards: enable MICROPY_HW_ENABLE_USBDEV on boards with USB CDC
- Makefile: allow external board definitions
- modules/machine: enable code formatting
- fix non-running LFCLK
- modules/machine: catch exceptions from pin interrupts
- modules/machine/pwm: tag a PWM device as used in the constructor
- main: fix build of microbit when SD is enabled
- Makefile: clean up dangling LIBS declaration
- mpconfigport: enable MICROPY_NLR_THUMB_USE_LONG_JUMP on nRF51xx

pic16bit port: no changes specific to this component/port

powerpc port: no changes specific to this component/port

qemu-arm port:
- mpconfigport: use MICROPY_CONFIG_ROM_LEVEL_EXTRA_FEATURES

renesas-ra port:
- ra: fix SysTick clock source
- ra: remove unnecessary min_delay() declaration
- boards/ARDUINO_PORTENTA_C33: fix the RTC clock source
- ra/ra_i2c: fix 1 byte and 2 bytes read issue
- fix spelling mistakes found by codespell
- boards: add named pins for Arduino Portenta C33
- boards/ARDUINO_PORTENTA_C33: add Arduino's external library

rp2 port:
- rp2_flash: lockout second core only when doing flash erase/write
- mutex_extra: implement additional mutex functions
- mpthreadport: fix race with IRQ when entering atomic section
- rp2_dma: fix fetching 'write' buffers for writing not reading
- provide direct memory access to PIO and SPI FIFOs via proxy arrays
- machine_uart: fix event wait in uart.flush() and uart.read()
- mpconfigport: allow MICROPY_PY_THREAD to be disabled by a board
- mpthreadport: make result of thread.get_ident() a non-zero integer
- machine_uart: fix potential race condition in interrupt handling
- boards/ARDUINO_NANO_RP2040_CONNECT: increase flash storage space
- change machine.I2S and rp2.DMA to use shared DMA IRQ handlers
- boards: add named digital pins for Arduino Nano RP2040 Connect
- enable support for Python USB devices
- CMakeLists: apply O2 optimisation to map, mpz and vm source code
- modmachine: prevent lock-up when lightsleep() called within thread
- README: fix typo, improve sentence about building with other boards
- boards/W5500_EVB_PICO: update incorrect url in board.json

samd port:
- remove the MICROPY_PY_MACHINE_RTC config option
- mcu/samd21: reorganize and enable more firmware features
- mcu: fix wrong EIC table entries in pin-af-table.csv
- mpconfigport: simplify and consolidate config options
- mcu/samd21: enable MICROPY_STACK_CHECK on SAMD21
- enable support for Python USB devices
- README: fix incorrect port directory name
- boards: enable MICROPY_HW_DFLL_USB_SYNC on appropriate boards
- mcu: update clock config after changes to USB
- samd_spiflash: allow configuring the flash SPI baudrate
- samd_qspiflash: avoid reading status byte 2 when not available
- mcu: guard static function with appropriate #if

stm32 port:
- mboot: improve detection of invalid flash erase/write
- mboot: improve mass erase to erase all non-protected pages
- flash: remove commented-out flash functions
- flash: simplify sector calculation for homogeneous flash layout
- flash: change flash_erase to only erase a single sector at a time
- flashbdev: don't rely on flash sector id
- flash: factor and simplify erase code
- flash: fix sector and bank calculation for H5 and H7 MCUs
- mboot/Makefile: revert change to BOARD_DIR that removed abspath
- disable qstr hashing on small boards
- boards/ARDUINO_PORTENTA_H7: add pin configuration for SPI1
- modos: allow disabling MICROPY_PY_MACHINE_UART
- spi: allow disabling MICROPY_PY_MACHINE_SPI
- main: allow disabling MICROPY_PY_MACHINE
- Makefile: ignore uninitialised variable warning in H5 HAL SD code
- mboot: generate FLASH_LAYOUT_STR at runtime on H5 MCUs
- mpbthciport: allow building with MICROPY_PY_MACHINE_UART disabled
- sdram: support remapping FMC memory banks
- network_lan: allow defining phy_addr in the LAN constructor
- eth: remove redundant ETH clock enable code
- network_lan: add the phy_type=x keyword option to network.LAN()
- simplify D-cache clean and invalidate macros
- mpu: rename MPU_CONFIG_DISABLE to MPU_CONFIG_NOACCESS
- dma: add D-cache protection for DMA RX operations, including SPI
- add support for dual-analog-pad "_C" pins on H7 MCUs
- boards: add named digital and analog pins for Arduino boardrs
- sdram: fix MPU config to use MPU_CONFIG_NOACCESS
- mpu: add MPU config for shared, uncached memory region
- implement port backend for libmetal
- implement port backend for OpenAMP's remoteproc
- boards/ARDUINO_GIGA: enable OpenAMP
- boards/ARDUINO_NICLA_VISION: enable OpenAMP
- boards/ARDUINO_PORTENTA_H7: enable OpenAMP
- mboot: add support for a raw filesystem
- boards/LEGO_HUB_NO6: move robust logic to mboot
- boards/LEGO_HUB_NO6: use a raw filesystem for mboot to update fw
- stm32.mk: enable _Float16 support on MCUs with hardware floats
- boards/ARDUINO_GIGA: add Arduino's external library
- boards/ARDUINO_NICLA_VISION: add Arduino's external library
- boards/ARDUINO_PORTENTA_H7: add Arduino's external library
- README: update list of supported STM32 series
- set the security mode for the default WiFi AP
- mpremoteprocport: use metal logging functions
- boards/LEGO_HUB_NO6: write key after writing elements
- boards/LEGO_HUB_NO7: add robust update logic to mboot
- flash: fix writing final words to flash on H5 and H7 MCUs
- mboot: buffer the correct amount of bytes for a flash write
- i2c: fix clock enable for I2C4 on STM32F7 MCUs
- pyb_can: fix STM32G4 FDCAN source clock frequency

unix port:
- variants: prefer unix-ffi packages when loading the manifest
- input: flush the prompt after writing it to stdout
- don't include system headers when features are disabled
- variants: don't use native _Float16 type

webassembly port:
- Makefile: remove --memory-init-file from linker options
- include lib in sys.path
- move MP_JS_EPOCH init to library postset
- implement MICROPY_PY_RANDOM_SEED_INIT_FUNC
- enable time localtime, gmtime, time, time_ns
- use POSIX write for output and add stderr
- add support for enabling MICROPY_GC_SPLIT_HEAP_AUTO
- clean up Makefile and add variant support
- add JavaScript proxying, and js and jsffi modules
- implement runPythonAsync() for top-level async code
- implement runCLI() for a Node-based CLI
- implement replInit() and replProcessChar()
- variants/pyscript: add pyscript variant
- update README.md to describe latest changes
- library: fix formatting and style for Biome
- proxy_c: ensure return value of async fun is passed to JS
- proxy_js: promote Python thenable to a Promise
- proxy_js: allow a Python proxy of a function to be undone
- api: fix waiting for Emscripten module to be loaded
- api: allocate code data on C heap when running Python code
- objjsproxy: fix handling of thrown value into JS generator
- proxy_c: fix proxy then reject handling
- proxy_c: fix then-continue to convert reason to throw value
- modjsffi: add jsffi.async_timeout_ms
- add JavaScript-based asyncio support
- api: inject asyncio.run if needed by the script
- api: fix importing micropython.mjs module from node REPL
- proxy_c: reject promises with a PythonError instance
- proxy_c: only proxy across resolve/reject funs when needed
- objjsproxy: fix proxying in arguments to JS new function
- objpyproxy: implement JS iterator protocol for Py iterables
- api: resolve thenables returned from runPythonAsync
- proxy_c: support more than 4 args when JS calls Py func
- asyncio: fix case where a Promise is resolved with no arg
- proxy_c: ensure objs thrown into generators are exceptions
- proxy_js: convert JS undefined and JS null to Py None
- mpconfigport: enable importing of .mpy files
- proxy_js: revert back to converting Py None to JS null
- proxy_js: create a special "undefined" type for Python
- proxy_c: return undefined if dict lookup failed on JS side
- objjsproxy: make jsproxy_it keep ref to jsproxy
- proxy_c: don't return value of a void function
- track the current depth of calls to external C functions
- set GC threshold and do top-level GC collect when possible
- add C-level finaliser to JsProxy object
- register PyProxy objects for JS-side finalisation
- modjsffi: add mem_info function to get detailed stats

windows port:
- windows_mphal: fix mp_hal_delay_ms() so it runs events
- Makefile: fix float exact int formatting on 32-bit mingw

zephyr port: no changes specific to this component/port

Patch release for rp2 DMA, UART and BLE, esp32 BLE, renesas-ra I2C

This is a patch release containing the following commits:
- py/compile: fix potential Py-stack overflow in try-finally with return
- extmod/asyncio: support gather of tasks that finish early
- extmod/modssl_mbedtls: fix cipher iteration in SSLContext.get_ciphers
- extmod/btstack: reset pending_value_handle before calling write-done cb
- extmod/btstack: reset pending_value_handle before calling read-done cb
- esp32/mpnimbleport: release the GIL while doing NimBLE port deinit
- esp32: increase NimBLE task stack size and overflow detection headroom
- mimxrt/modmachine: fix deepsleep wakeup pin ifdef
- renesas-ra/ra: fix SysTick clock source
- renesas-ra/boards/ARDUINO_PORTENTA_C33: fix the RTC clock source
- renesas-ra/ra/ra_i2c: fix 1 byte and 2 bytes read issue
- rp2/rp2_dma: fix fetching 'write' buffers for writing not reading
- rp2/machine_uart: fix event wait in uart.flush() and uart.read()
- rp2: change machine.I2S and rp2.DMA to use shared DMA IRQ handlers

Patch release for rp2 atomic mutex

This is a patch release to fix a race condition and potential deadlock in
the rp2 port's mp_thread_begin_atomic_section() function, when the second
core is in use.

SSL support in asyncio, sorted qstr pools, common machine module bindings

This release of MicroPython introduces SSL/TLS support to asyncio, for both
the client and server sides.  The interface matches CPython:
`asyncio.open_connection()` and `asyncio.start_serve()` now both accept an
`ssl` argument to supply an `SSLContext` object.  As part of this, new
methods were added to `SSLContext` to load certificates, and certificate
date/time validation was enabled on all ports that use mbedTLS.

Qstr pools are now sorted, which provides a significant performance boost
for `qstr_find_strn()`, which is called a lot during parsing and loading of
.mpy files, as well as interning of string objects, which happens in most
string methods that return new strings.  The static pool (part of the .mpy
ABI) isn't currently sorted, but could be in the future.

There have been many internal changes to the `machine` module (and on some
ports the `os` module) to factor the Python bindings to a common location,
reduce code duplication and make the API more consistent across all the
ports.  And a new `boardgen.py` script has been added to factor pin
generation and enable a more consistent `machine.Pin` across ports.  For
consistency, the following user-facing changes have been made:

- cc3200 port: The `machine` module gains `soft_reset()`, `mem8`, `mem16`,
  `mem32` and `Signal`; it loses `POWER_ON` (replaced by `PWRON_RESET`).
  `disable_irq()` now returns an (opaque) integer rather than a bool, and
  `enable_irq(state)` must be passed an argument which is the return value
  of `disable_irq()`, rather than a bool.  In the `os` module, `dupterm()`
  has been converted to use the common implementation and has semantics the
  same as other ports, and `uname()` is removed to save space (sys.version
  and sys.implementation can be used instead).

- esp32 port: In the `machine` module, `lightsleep()` and `deepsleep()` no
  longer take the `sleep` keyword argument, instead it's positional to
  match other ports.  Also, passing 0 here will now do a 0ms sleep instead
  of acting like nothing was passed.  And `reset_cause()` no longer accepts
  any arguments (before it would just ignore them).

- esp8266 port: `machine.idle()` now returns None instead of the time
  elapsed.  The `machine.WDT()` constructor now takes keyword arguments,
  and accepts the `timeout` argument but raises an exception if it's not
  the default value (this port doesn't support changing the timeout).

- mimxrt port: `machine.freq()` now accepts an argument but raises
  `NotImplementedError`, and `machine.lightsleep()` has been added but also
  just raises `NotImplementedError` (this is to make these functions use an
  implementation common to the other ports).

- nrf port: The `machine` module gains `unique_id()` (returns an empty
  bytes object), `freq()` (raises `NotImplementedError`) and `Signal`.
  `UART.sendbreak()` is removed, but this method previously did nothing.
  The `os.dupterm()` function has changed to match the semantics used by
  all other ports (except it's restricted to accept only `machine.UART`
  objects).

- qemu-arm port: The `machine` module gains `soft_reset()` and `idle()`.

- samd port: The `machine.deepsleep()` function now resets after sleeping.

- unix port: Gains `machine.soft_reset()`.

- zephyr port: The `machine` module gains `soft_reset()`, `mem8`, `mem16`,
  and `mem32`.  The `UART` class gains the following methods: `init()`
  which supports setting `timeout` and `timeout_char`, `deinit()` which
  does nothing, `flush()` which raises `OSError(EINVAL)` because it's not
  implemented, and `any()` and `txdone()` which both raise
  `NotImplementedError`.

The teensy port has been removed in this release.  This port was largely
unmaintained, had limited features (the only hardware support was for GPIO
and timer, and no `machine` module), and only supported a small number of
Teensy boards.

A new preview versioning scheme has been introduced, whereby non-release
builds are a preview of the next, upcoming release.  This scheme is
compatible with semver and should help to eliminate confusion matching
documentation and firmware version numbers, among other things.

Black has been replaced with ruff format as the Python code formatter.
This required a few small changes to Python code, and now allows linting
and formatting with ruff.

Bound method instances now support comparison and hashing, matching CPython
semantics.  The .mpy sub-version has been updated from 6.1 to 6.2 due to a
change in the native .mpy ABI.  A new option `MICROPY_PREVIEW_VERSION_2`
has been added which provides a way to enable features and changes slated
for MicroPython 2.x, by running `make MICROPY_PREVIEW_VERSION_2=1`.  This
is an alternative to having a 2.x development branch, and any feature or
change that needs to be "hidden" until 2.x will use this flag.

LittleFS has been updated to v2.8.1.  The associated MicroPython VfsLfs2
driver can read existing LFS2 filesystems, but any writes will update the
filesystem to a newer LFS2 version that cannot be read by older drivers, so
take this into account when updating, for example update mboot first.

The VFS sub-system has a new file ioctl to set the read-buffer size, which
is used by mpremote to significantly increase performance of the
"mpremote mount" feature.  Manifest files now allow registering an external
library path via `add_library(name, path)`.  `sys.stdout.buffer.write()`
now returns the actual number of bytes written (although this is
complicated when output goes to multiple destinations).

The esp32 port has been updated to use IDF version 5.0.4, and the initial
GC heap size tuned so that, after doubling the heap size, WiFi can still be
started and an SSL connection made.  `RMT.source_freq()` is now a class
method, socket connect timeout has been implemented, RTC user memory is now
preserved over most reset causes, and `hashlib.md5` enabled.

The mimxrt port has RTC alarm/wakeup functionality added, along with
support for `machine.deepsleep()`.

The rp2 port sees the introduction of a new `rp2.DMA` class for control
over DMA transfers.  It has switched to use the same math library as other
ports to get more accurate floating point behaviour, and enabled
`os.dupterm_notify()` for WebREPL use.  The TinyUSB stack is now scheduled
to run from the IRQ handler (instead of polled in the VM) which slightly
improves performance of the VM and USB.  The port also makes better use of
event scheduling and WFE to be more efficient.  It also has added support
for external ADC channels (for example when using the ninaw10 driver).

The stm32 port has improved support for STM32H5xx MCUs, including Ethernet
support, frequency scaling with HSI, sleep mode and SD card support.  The
NUCLEO_WL55 board now freezes in the LoRa driver, the I2S driver has
improved accuracy of the clock frequency, and mboot now supports Microsoft
WCID to set the USB driver.

New boards added in this release are: UM_TINYWATCHS3 (esp32 port),
POLOLU_3PI_2040_ROBOT, POLOLU_ZUMO_2040_ROBOT and SIL_RP2040_SHIM (rp2
port), NUCLEO_H563ZI (stm32 port).

The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):

       bare-arm:   +216  +0.381%
    minimal x86:   +624  +0.340%
       unix x64:  +8283  +1.050%
          stm32:  +1368  +0.350%
         cc3200:  +1184  +0.649%
        esp8266:   +800  +0.114%
          esp32: +35348  +2.100%
         mimxrt:  +2172  +0.602%
     renesas-ra:    +96  +0.015%
            nrf:  +1460  +0.785%
            rp2:  +6100  +1.880%
           samd:  +1476  +0.568%

The changes that dominate these numbers are:
- bare-arm, minimal: comparing and hashing bound methods, sorted qstr pools
- unix: updating LittleFS to 2.8.1, enabling certificate date/time
  validation, adding SSLContext certificate methods, asyncio SSL support
- stm32: sorted qstrs, updating LittleFS to 2.8.1, I2S clock frequency
  improvements, asyncio SSL support
- cc3200: sorted qstrs, more machine module functions, use of the common
  `os.dupterm` implementation
- esp32: switching ESP-IDF from 5.0.2 to 5.0.4
- esp8266: updating LittleFS to 2.8.1
- mimxrt: adding RTC alarm/wakeup functionality, updating LittleFS to
  2.8.1, asyncio SSL support
- nrf: updating LittleFS to 2.8.1, enabling `machine.Signal`, asyncio SSL
  support
- rp2: using locally-provided math library, adding new `rp2.DMA` class
- samd: sorted qstrs, updating LittleFS to 2.8.1, asyncio SSL support

With the new sorted qstr pools, performance is significantly improved for
qstr-heavy operations, between +50% and +200% improvement.  Other areas
have their performance unchanged since the last release.

Thanks to everyone who contributed to this release: Alessandro Gatti,
Andrew Leech, Angus Gratton, Carlosgg, Christian Walther, Damien George,
Daniël van de Giessen, Elias Wimmer, Glenn Moloney, iabdalkader, Ihor
Nehrutsa, Jeff Epler, Jim Mussared, Kwabena W. Agyeman, Maarten van der
Schrieck, Mark Blakeney, Mathieu Serandour, Matthias Urlichs, MikeTeachman,
Ned Konz, Nicko van Someren, Pascal Brunot, Patrick Van Oosterwijck, Paul
Grayson, Peter Züger, Rene Straub, robert-hh, Scott Zhao, Sebastian Romero,
Seon Rozenblum, stijn, Thomas Ackermann, Thomas Wenrich, ThomHPL, Trent
Piepho.

Contributions were made from the following timezones: -0800, -0700, -0600,
-0500, +0000, +0100, +0200, +1000, +1100.

The work done in this release was funded in part through GitHub Sponsors,
and in part by George Robotics, Planet Innovation, Espressif, Arduino, LEGO
Education and OpenMV.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- switch to new preview build versioning scheme
- replace "black" with "ruff format"
- update Python formatting to ruff-format

py core:
- vm: don't emit warning when using "raise ... from None"
- builtinevex: handle invalid filenames for execfile
- objboundmeth: support comparing and hashing bound methods
- objboundmeth: optimise check for types in binary_op
- obj: generalise mp_get_buffer so it can raise if a flag is set
- dynruntime: add mp_get_buffer
- persistentcode: bump .mpy sub-version
- modthread: initialise nlr_jump_callback_top on threads
- makeqstrdefs.py: print a nicer error when preprocessing stage fails
- mkrules.mk: add MICROPY_PREVIEW_VERSION_2
- asm: remove unused asm helper macros
- qstr: add support for sorted qstr pools
- mkrules.mk: add rule for compiling auto-generated source files
- runtime: remove declaration of function from inside function
- lexer: change token position for new lines
- misc: change sizeof to offsetof for variable-length alloc
- qstr: special case qstr_find_strn for empty string
- obj: fix mp_obj_is_type compilation with C++
- objslice: validate that the argument to indices() is an integer
- mkrules: add support for custom manifest variables
- modbuiltins: share vstr_add_char's implementation of utf8 encoding
- mphal: move configuration of ATOMIC_SECTION macros to mphal.h
- add port-agnostic inline functions for event handling
- modsys: implement optional sys.intern
- mkrules.mk: list hash files as byproducts
- makeqstrdefs.py: don't skip output for stale hash file
- makeqstrdefs.py: stop generating temporary intermediate file
- gc: improve calculation of new heap size in split-heap-auto mode
- mkrules.mk: fix dependency file generation for compiler wrappers

extmod:
- moductypes: validate that uctypes.struct addr argument is an int
- asyncio: emit errors to stderr, not stdout
- modframebuf: validate FrameBuffer bounds against input buffer
- modframebuf: fix FrameBuffer get-buffer implementation
- modframebuf: remove FrameBuffer1 from natmod build
- vfs_posix: fix relative root path
- vfs_posix: fix accidentally passing tests
- vfs_posix: fix relative paths on non-root VFS
- vfs_posix: fix getcwd() on non-root VFS
- vfs_posix: additional tests for coverage of error cases
- network_ninaw10: raise an error if nina_ioctl fails
- machine_wdt: factor ports' WDT Python bindings to common code
- machine_pwm: remove header file and move decls to .c file
- machine_i2s: factor ports' I2S Python bindings to common code
- machine_i2s: factor stream and ring-buf code
- machine_i2s: factor I2S.shift method
- machine_i2s: factor I2S.irq method
- machine_i2s: factor print function
- machine_i2s: factor init_helper argument parsing
- machine_i2s: factor comments, some enums and macros
- machine_adc: factor ports' ADC Python bindings to common code
- machine_uart: factor ports' UART Python bindings to common code
- modmachine: clean up decls of machine types to use common ones
- modmachine: consolidate simple machine headers into modmachine.h
- modmachine: consolidate mem, i2c and spi headers to modmachine.h
- network_ninaw10: fix select flags handling in socket poll
- remove empty utime_mphal.h file
- machine_adc_block: factor esp32 ADCBlock bindings to common code
- machine_i2c: do a fast poll during I2C.scan()
- vfs_reader: add file ioctl to set read buffer size
- modbluetooth: initialise nlr_jump_callback_top for IRQ handlers
- vfs_posix_file: make standard file objects non-const
- extmod.mk: allow enabling lwip loopback support
- modmachine: make I2C/SPI defns available when soft impl enabled
- modmachine: factor ports' machine module dict to common code
- modmachine: provide common Python bindings for machine.idle()
- modmachine: add MICROPY_PY_MACHINE_PIN_BASE option
- modmachine: provide common Python bindings for bootloader()
- modmachine: provide common bindings for 6 bare-metal functions
- modmachine: provide common implementation of disable/enable_irq
- mbedtls: enable certificate time/date validation by default
- modnetwork: add deinit function to NIC protocol
- network_ninaw10: switch to using soft-timer for polling
- switch to use new event functions
- add lists of libm/libm_dbl source files for ports to use
- modssl_mbedtls: add SSLContext certificate methods
- modssl_mbedtls: make SSLSocket.getpeercert() optional
- modssl_mbedtls: fix parsing of ciphers in set_ciphers method
- asyncio: add ssl support with SSLContext
- modonewire: adopt Maxim recommended read timings
- modonewire: improve write timings for better reliability
- modos: factor os.dupterm_notify() function to common extmod code
- os_dupterm: prevent recursive execution of mp_os_dupterm_rx_chr
- asyncio: remove non-working Stream __aenter__/__aexit__ methods
- modselect: handle growing the pollfds allocation correctly
- modhashlib: support MD5 with mbedtls 3.x
- os_dupterm: let mp_os_dupterm_tx_strn() return num bytes written
- vfs_lfs: fix lfs cache_size calculation
- nimble: do not set GAP device name after sync

shared:
- libc/string0: don't deref args for n==0 case
- tinyusb: schedule TinyUSB task function from dcd_event_handler
- tinyusb: expose mp_usbd_task as a public function
- tinyusb: add a helper for hex string conversion
- runtime/softtimer: generalise soft_timer to work without SysTick

drivers:
- ninaw10: add ioctl for reading analog pins
- ninaw10: add support for external ADC channels

mpy-cross: no changes specific to this component/port

lib:
- littlefs: update LittleFS to v2.8.1
- uzlib: for matches of the same length, take the closest one
- mbedtls_errors: update error list for latest esp32 mbedtls
- micropython-lib: update submodule to latest

Support components
==================

docs:
- reference/mpyfiles: document change in .mpy sub-version
- library/io: remove io.FileIO and io.TextIOWrapper
- reference/micropython2_migration: add migration guide
- mimxrt: change the examples which denote a Pin with a number
- samd: fix the pinout for SAMD21 Itsy Bitsy Express M0
- library/esp: correct the description of esp.osdebug()
- esp32/quickref: add DAC example
- library: document SSLContext cert methods and asyncio support

examples:
- pins.py: remove this pins printing example

tests:
- basics/boundmeth1.py: add tests for bound method equality/hash
- perf_bench: add string/qstr/map tests
- extmod/asyncio_as_uasyncio.py: fix qstr order dependency
- net_hosted/asyncio_loopback.py: add loopback test
- extmod/deflate_compress.py: add a test for optimal compression
- float/inf_nan_arith.py: include -inf in argument combos
- run-tests.py: skip Thumb2 tests if target doesn't support them
- update SSL network tests to use SSLContext, and work on CPython

tools:
- ci.sh: ensure enough commits are fetched for a common ancestor
- boardgen.py: add initial implementation of a common make-pins.py
- tinytest-codegen.py: externalise tests list
- mpremote: add ioctl to specify large read buffer size
- ci.sh: build ESP32_GENERIC-SPIRAM as part of esp32 CI
- ci.sh: set `ulimit -n` for unix CI
- manifestfile.py: add support for external libraries

CI:
- workflows: pin ruff to 0.1.0 and change flags for new version
- workflows: cache ESP-IDF checkout and installation
- workflows: use build matrix for esp32 port
- workflows: enable build matrix for stm32 port
- workflows: enable ccache for esp32 build
- workflows: bump actions/github-script from 6 to 7
- workflows: bump actions/setup-python from 4 to 5
- workflows: bump actions/upload-artifact from 3 to 4

The ports
=========

all ports:
- make all ports skip execution of main.py if boot.py fails
- remove SRC_QSTR_AUTO_DEPS from all ports' Makefiles
- standardise arguments and output for make-pins.py script
- fix incorrect identifiers on Arduino boards
- move definitions of ATOMIC_SECTION macros to mphalport.h
- switch build to use common lib/libm list of source files
- fix sys.stdout.buffer.write() return value

bare-arm port:
- lib: add minimal strncmp implementation

cc3200 port:
- boards/make-pins.py: don't generate qstrs
- boards/make-pins.py: add a note about tools/boardgen.py
- mods/modmachine: use common implementation of disable/enable_irq
- convert dupterm to use common extmod implementation
- convert os module to use extmod version
- eliminate dependency on stm32's irq.h
- application.mk: don't add stm32 to build include path

embed port: no changes specific to this component/port

esp8266 port:
- rename MICROPY_ESPNOW to MICROPY_PY_ESPNOW
- machine_spi: rename machine_hspi to machine_spi
- esp_mphal: make atomic section more atomic
- modmachine: use common implementation of disable/enable_irq
- avoid including ep_mphal.h directly
- update port to use new event functions

esp32 port:
- rename MICROPY_ESPNOW to MICROPY_PY_ESPNOW
- boards: update UM board image names for consistency
- boards/UM_TINYWATCHS3: add new UM TinyWATCH S3 board
- boards: update UM board settings to use custom PID/VID
- network_ppp: allow building with IPv6 disabled
- poll serial/JTAG for unread data to prevent blocking
- mpconfigport: remove port-specific GAP name
- machine_uart: add error checking for IDF API's
- network_ppp: reduce PPP thread CPU usage
- boards: disable ALPN support
- network_lan: fix and simplify the code for ETH-SPI devices
- network_lan: fix LAN.isconnected()
- network_lan: register the hostname setting for Ethernet
- modmachine: fix deepsleep() when previous sleep delay was set
- boards: reduce size of D2WD and OTA firmware
- use better build settings for ESP32-C3
- mphalport: add function to wake main from separate FreeRTOS task
- usb: wake main thread when USB receives data
- machine_pin: make irq object a sub-field of pin object
- esp32_rmt: change RMT.source_freq() to class method
- esp32_rmt: add RMT.PULSE_MAX constant
- modsocket: implement socket connect timeout
- modsocket: try garbage collection if the socket limit is reached
- boards/sdkconfig.base: fix increasing log level via esp.osdebug()
- boards/ESP32_GENERIC: reduce size of D2WD variant to fit in flash
- uart: preserve console UART clock, fix UART console with DFS
- uart: make compatible with sclk type change in ESP-IDF 5.3
- network_wlan: reduce RAM usage if SPIRAM fails to initialise
- network_wlan: fix network.WLAN.status() to return better info
- esp32_rmt: fix RMT looping
- enable mbedtls cert time validation
- boards: enable further IRAM saving opts to fit ESP32-SPIRAM fw
- machine_rtc: preserve RTC user memory over most reset causes
- boards/UM_TINYPICO: fix typo in baudrate instructions
- boards/sdkconfig.base: disable unused mbedtls options
- machine_i2c: use APB_CLK_FREQ instead of I2C_APB_CLK_FREQ
- modnetwork: add WiFi AUTH_WPA3_ENT_192 authenticate mode
- machine_dac: support one-shot mode of driver
- modmachine: fix deprecated esp_pm_config_XXX_t
- machine_i2s: fix deprecated fields and constants
- mpconfigport: keep some funcs out of IRAM for ESP32-SPIRAM builds
- boards/ESP32_GENERIC: disable network.LAN and VM-opt on D2WD
- change minimum supported IDF version to v5.0.4
- re-enable custom mbedtls error string tables
- add MICROPY_GC_INITIAL_HEAP_SIZE option and tune it
- mpconfigport: enable MICROPY_PY_HASHLIB_MD5

mimxrt port:
- led: fix LED init call from main, and simplify led_init
- boards: define missing SNVS pins for all processors
- machine_rtc: add RTC alarm/wakeup functionality
- modmachine: add support for machine.deepsleep
- boards/make-pins.py: update to use tools/boardgen.py
- modmachine: fix settings for the MIMXRT1170 board
- boards/OLIMEX_RT1010: adjust the UART pin assignment

minimal port: no changes specific to this component/port

nrf port:
- boards: automatically configure MICROPY_PY_MACHINE_PWM
- modules/machine: use SPI Python bindings provided by extmod
- boards/make-pins.py: don't generate qstrs
- boards/make-pins.py: add a note about tools/boardgen.py
- use MICROPY_PY_MACHINE_SPI instead of MICROPY_PY_MACHINE_HW_SPI
- use dupterm_objs[0] instead of board_stdio_uart
- convert os module to use extmod version
- mpconfigport: enable MICROPY_PY_MACHINE_BOOTLOADER
- boards/ARDUINO_NANO_33_BLE_SENSE: don't enable MICROPY_MBFS
- main: add /flash and /flash/lib to sys.path

pic16bit port: no changes specific to this component/port

powerpc port: no changes specific to this component/port

qemu-arm port: no changes specific to this component/port

renesas-ra port:
- boards/make-pins.py: don't generate qstrs
- boards/make-pins.py: update to use tools/boardgen.py
- boards/ARDUINO_PORTENTA_C33: fix incorrect I2C pins
- consolidate MICROPY_PY_MACHINE_I2C option

rp2 port:
- cyw43_configport: use m_tracked_calloc and m_tracked_free
- machine_adc: add support for external ADC channels
- boards/ARDUINO_NANO_RP2040_CONNECT: add external analog pins
- boards/make-pins.py: don't generate qstrs
- machine_uart: fix handling of serial break condition
- machine_adc: refactor channel/pin validation code
- remove 1ms timeout to make idle waiting tickless
- change to use TinyUSB dcd_event_handler hook
- mphalport: run TinyUSB stack while waiting for CDC input/output
- integrate soft_timer using the alarm pool
- mpbthciport: rework HCI polling timer to use soft_timer
- mpnetworkport: rework lwIP polling to use soft_timer
- mphalport: optimise exit of mp_hal_delay_ms loop
- cyw43_configport: implement cyw43_delay_ms as mp_hal_delay_ms
- switch to locally provided math library
- switch rp2 and drivers to use new event functions
- main: enable SEVONPEND CPU interrupt bit
- mpconfigport: enable MICROPY_PY_OS_DUPTERM_NOTIFY
- add new NO_DEFAULT_PINS config options for i2c, spi, and uart
- boards: add support for Pololu 3pi+ and Zumo robots
- boards: add SIL_RP2040_SHIM board by Silicognition LLC
- rp2_dma: introduce a new rp2.DMA class for control over DMA xfers

samd port:
- boards/make-pins.py: update to use tools/boardgen.py
- mpconfigport: set MICROPY_USE_INTERNAL_ERRNO to 1
- machine_uart: add machine_uart_set_baudrate() function
- pin_af: fix a typo in a conditional compile
- switch TinyUSB to run via a scheduled task
- mphalport: run TinyUSB stack while waiting for CDC input/output
- switch to shared TinyUSB implementation
- use unique id for USB serial number

stm32 port:
- boards/ARDUINO_GIGA: add QSPI fix/workaround to early init
- boards/ARDUINO_GIGA: fix name of pins in board init
- eth: add Ethernet support for H5 MCUs
- boards/STM32H573I_DK: enable ETH and DAC peripherals
- powerctrl: add support for frequency scaling with HSI on H5 MCUs
- boards/make-pins.py: don't generate qstrs
- boards: fix errors in pins.csv and af.csv
- boards: format stm32 alternate function csv files
- rename pin_obj_t to machine_pin_obj_t
- boards/make-pins.py: update to use tools/boardgen.py
- boards/make-pins.py: add initial support for H7 dual-pad pins
- add configuration options for analog switches
- add STM32H5 support for sleep mode
- boards/make-pins.py: fix H7 ADC generation
- boards/stm32f4x9_af.csv: fix DCMI_VSYNC
- boards/stm32g474_af.csv: fix final row ADC column
- boards/make-pins.py: only support ADC1-3
- boards/NUCLEO_WL55: freeze LoRa driver
- mpu: enable STM32WB mpu use to support qspi flash
- add optional lwip loopback support
- boards/NUCLEO_F446RE: add UARTs 1, 3 and 4
- boards/NUCLEO_H563ZI: add new NUCLEO-H563ZI board definition
- sdcard: add SD card support for H5 MCUs
- boards/STM32H573I_DK: enable the SD card
- add missing header include for debug builds
- modmachine: only enable machine.I2C if hardware I2C is enabled
- usbd_cdc_interface: include header to get machine_bootloader decl
- machine_i2s: improve accuracy of SCK frequency
- usbdev: optionally pass through vendor requests to Setup function
- mboot: guard use of tx_pending with USE_USB_POLLING option
- mboot: expand device descriptor to make it easier to understand
- mboot: add support for Microsoft WCID

teensy port:
- remove the teensy port

unix port:
- mbedtls: enable mbedtls cert time validation
- update port to use the new event functions

webassembly port: no changes specific to this component/port

windows port:
- use the MicroPython logo as application icon
- implement MICROPY_INTERNAL_WFE() macro

zephyr port: no changes specific to this component/port

U-module renaming, deflate module, IDF 5, board variants and Pico-W BLE

This release of MicroPython sees the renaming of built-in modules to remove
the u-prefix, a new deflate module with optional compression support, the
introduction of board variants, switching of the esp32 port to use IDF 5
together with improved heap management, support for BLE on RPi Pico W
boards, and STM32H5xx support.  The project is also now using codespell and
ruff to improve code quality.  New boards added in this release are:
ARDUINO_NANO_ESP32 and UM_NANOS3 (esp32 port), ADAFRUIT_METRO_M7 (mimxrt
port), ARDUINO_PORTENTA_C33 and VK_RA6M5 (renesas-ra port),
ADAFRUIT_METRO_M4_EXPRESS (samd port), NUCLEO_L4A6ZG and STM32H573I_DK
(stm32 port).

The renaming of built-in modules to remove the u-prefix -- for example
utime becomes time, uasyncio becomes asyncio -- is done to improve
compatibility with CPython and eliminate confusion about whether to import
the u-version or the non-u-version of the name.  Now, one should just
always import the non-u-version and no longer think about u-naming.  The
only remaining module with a u-prefix is uctypes because it is not
compatible with the CPython ctypes modules.  The following modules are
still available via their u-names for backwards compatibility: array,
asyncio, binascii, bluetooth, collections, cryptolib, errno, hashlib,
heapq, io, json, machine, os, platform, random, re, select, socket, ssl,
struct, time, websocket.  These modules (except for asyncio) are also
extensible and can be overridden by a file with the same name, eg time.py.
To force the import of a built-in, one must first clear (and subsequently
restore) sys.path; the ability to write to the sys.path attribute has also
been implemented in this release.  For further information see the
discussion at https://github.com/micropython/micropython/issues/9018.

Furthermore, importing itself has been tweaked and optimised, and importing
of built-ins no longer touch the filesystem, which makes a typical built-in
import take ~0.15ms rather than 3-5ms.  For modules that fail to import,
they are now removed from sys.modules, allowing the import to be attempted
again.  This required adding "NLR jump callbacks" to efficiently run some
code if an exception is raised.

Additional improvements to the core runtime include support for conversion
specifiers in f-strings (e.g. !r), speeding up of incremental GC cycles by
tracking the last used block, addition of a new MICROPY_GC_SPLIT_HEAP_AUTO
"auto grow heap" mode and support for pad bytes in struct format.  The
documentation, examples and test have also seen general improvements and
additions.

For the extended modules, the zlib C module has been removed and replaced
with a new MicroPython-specific deflate module and DeflateIO class that is
optimised to provide efficient streaming compression and decompression.
The zlib (and gzip) modules are now implemented in pure Python on top of
the deflate module.  The timeq module has been removed, it existed only for
a previous version of (u)asyncio and is no longer used.  In the ssl
module, SSLContext has been added to be more compatible with CPython.  The
select module now supports using system/POSIX poll when possible and the
unix port now uses this implementation instead of its own one.  That means
the unix port can now select/poll on custom Python objects that implement
the appropriate ioctl.  The socket module now supports SO_BROADCAST, and
sys.std*.buffer objects now exist on unix.  There is also a new esp-hosted
network driver for external ESP32-based network coprocessors.

mpy-cross now allows reading source files from stdin and writing compiled
code to stdout.

The esp8266 and esp32 ports add support for the Espressif ESP-NOW protocol,
and the ability to set/get the power saving mode of the WLAN hardware.  The
esp8266 port adds board-variant support, combining all boards into a single
ESP8266_GENERIC with FLASH_512K, FLASH_1M and OTA variants.

The esp32 port has now switched exclusively to ESP-IDF 5, and all existing
components have been updated to work with this new IDF (except
esp32.hall_sensor() which has been removed).  The FSM ULP has been enabled
for S2 and S3 chips, sockets now support SO_BINDTODEVICE, and board-named
pins and the Pin.board dict have been implemented.  The MicroPython heap
has been reworked on this port to support the large variety of memory
configurations: it now starts at 64kbytes and automatically grows as
needed, with new segments allocated from the IDF heap.  This means that
boards with SPIRAM have much faster GC collection times if only a small
amount of RAM is used, all available RAM can be used if needed, and the IDF
has access to enough RAM for things like SSL sockets.  For more information
see https://github.com/micropython/micropython/pull/12141.  The esp32 port
has also had its generic boards consolidated and renamed to ESP32_GENERIC,
ESP32_GENERIC_C3, ESP32_GENERIC_S2 and ESP32_GENERIC_S3, and some now have
variants such as SPIRAM.

The mimxrt port has fixes and improvements to PWM and Pin.irq, as well as
support for UART hardware flow control and UART.deinit.  It has also seen
integration of WiFi via the CYW43 driver, and Bluetooth via NimBLE.  The
mbedTLS bindings have enabled time validation of certificates.

The renesas-ra port has changed board names to match the product name,
updated to use FSP v4.4.0, added support for: RA6M5 MCUs, machine PWM, DAC,
RNG and SDCard classes, TinyUSB, Bluetooth via NimBLE, networking via lwIP,
and mbedTLS.

Bluetooth support has also been added to the rp2 port for the Pico W board.
And the RPi boards have been renamed from PICO to RPI_PICO, and PICO_W to
RPI_PICO_W.  Lightsleep has been fixed on this port so it works while WiFi
is powered off, and time.time_ns() now has microsecond resolution.

The samd port sees the addition of SPI and QSPI flash drivers to support
filesystems on external flash.

The stm32 port add support for STM32H5xx MCUs, basic support for the
OCTOSPI peripheral, and USB support for STM32L1xx MCUs.  New functions have
been added to the stm module to support the sub-GHz radio on STM32WL55.

In micropython-lib, an extensive LoRa module has been added along with
drivers for SX126x and SX127x chipsets, and the STM32WL55.  This module
supports both synchronous and asynchronous (asyncio) mode.  Also, as part
of the u-module renaming, urequests has been renamed to requests (but for
backwards compatibility "import urequests" still works for now).

The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):

       bare-arm:    +192  +0.340%
    minimal x86:    +310  +0.169%
       unix x64:   +4784  +0.610%
          stm32:    -524  -0.134%
         cc3200:    +280  +0.154%
        esp8266:   +8016  +1.151%
          esp32: +112133  +7.293%
         mimxrt:   +3624  +1.015%
     renesas-ra:   -2184  -0.348%
            nrf:    +616  +0.332%
            rp2:   +1920  +0.595%
           samd:   -7904  -2.953%

The changes that dominate these numbers are:
- bare-arm, minimal, cc3200, nrf: NLR jump callbacks and support for
  extensible modules
- unix: update of mbedTLS to v2.28.1, support for polling Python objects in
  select module
- stm32: removal of the timeq module
- esp8266: addition of the espnow module
- esp32: switching to ESP-IDF 5
- mimxrt: UART features, time validation of SSL certificates
- renesas-ra: move to FSP v4.4.0, remove timeq module
- rp2: machine.PWM enhancements
- samd: drop support for VfsLfs1

Performance is effectively unchanged since the previous release.

Note that this is the last release to use the current versioning scheme for
nightly/unstable builds, whereby a build between releases is versioned as
v1.20.0-<num>-g<hash> (following the release of v1.20.0).  Moving forward,
nightly builds will now be called preview builds and be versioned with the
next release number.  For example, if the last release was v1.21.0 then
preview releases will be of the form v1.22.0-preview.<num>.g<hash>.  For
discussion see https://github.com/micropython/micropython/issues/12127.

Thanks to everyone who contributed to this release:
Adam Green, Alexander Wilde, algonell, Andrew Leech, Andy Piper, Angus
Gratton, Armin Brauns, brave ulysses, Brett Cannon, Brian 'redbeard'
Harrington, Carlosgg, Chris Wilson, Christian Clauss, Damien George, Damien
Tournoud, Daniël van de Giessen, David Grayson, David Lechner, David Yang,
dotnfc, Duncan Lowther, Elecia White, elibdev, Elvis Pfutzenreuter, Felix
Dörre, Francis Dela Cruz, Glenn Moloney, glenn20, iabdalkader, Ihor
Nehrutsa, Jared Hancock, Jim Lipsey, Jim Mussared, Jon Nordby, Jonas
Scharpf, Jos Verlinde, Kwabena W. Agyeman, Luca Burelli, marble, Mark
Grosen, mbedNoobNinja, mcskatkat, Mingjie Shen, Mirko Vogt, Nicholas H.
Tollervey, Oliver Joos, Ondrej Wisniewski, patrick, Peter Harper, Phil
Howard, Philipp Ebensberger, Rene Straub, robert-hh, Sebastian Romero, Seon
Rozenblum, stephanelsmith, stijn, Takeo Takahashi, Thomas, Tobias
Thyrrestrup, UnexpectedMaker, Victor Rajewski, vsfos, Wang Xuancong, Wanlin
Wang, Wilko Nienhaus, Wind-stormger, Yaroslav Halchenko, Yilin Sun, Yuuki
NAGAO.

The work done in this release was funded in part through GitHub Sponsors,
and in part by George Robotics, Planet Innovation, Espressif, Arduino, LEGO
Education and OpenMV.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- fix spelling mistakes based on codespell check
- fix strings with backslash by using raw string literals
- fix various Python coding inconsistencies found by ruff
- fix cases of Python variable assigned but never used
- rename MP_QSTR_umodule to MP_QSTR_module everywhere
- rename mp_umodule*, mp_module_umodule* to remove the "u" prefix
- rename mod_umodule*, ^umodule* to remove the "u" prefix
- rename UMODULE to MODULE in preprocessor/Makefile vars
- rename *umodule*.h to remove the "u" prefix
- rename *umodule*.c to remove the "u" prefix
- use MP_REGISTER_EXTENSIBLE_MODULE for overrideable built-ins
- replace all uses of umodule in Python code
- remove the zlib module
- remove query-variants make target
- add missing imports for micropython.const
- add Black configuration section to pyproject.toml
- add ruff to pre-commit
- CODECONVENTIONS: require that commits be signed-off by the author

py core:
- ringbuf: implement put_bytes/get_bytes functions
- parse: fix build when COMP_CONST_FOLDING=0 and COMP_MODULE_CONST=1
- compile: remove over-eager optimisation of tuples as if condition
- stackctrl: add gcc pragmas to ignore dangling-pointer warning
- gc: make improvements to MICROPY_GC_HOOK_LOOP
- obj: remove mp_generic_unary_op()
- objslice: ensure slice is not hashable
- objdict: fix __hash__ for dict_view types
- objarray: disallow memoryview addition
- objstr: return unsupported binop instead of raising TypeError
- runtime: if inplace binop fails then try corresponding normal binop
- change MP_UNARY_OP_INT to MP_UNARY_OP_INT_MAYBE
- obj: accept user types in mp_obj_get_int_maybe
- objint: allow int() to parse anything with the buffer protocol
- builtinimport: handle empty sys.path correctly
- builtinimport: optimise sub-package loading
- builtinimport: allow builtin modules to be packages
- objmodule: don't use sys.modules to track a builtin __init__
- nlrsetjmp: use MP_NLR_JUMP_HEAD macro to simplify code
- nlr: remove commented-out debugging code
- nlr: implement jump callbacks
- use nlr jump callbacks to optimise compile/execute functions
- builtinimport: remove partially-loaded modules from sys.modules
- builtinimport: remove weak links
- makemoduledefs.py: add a way to register extensible built-in modules
- objmodule: add a table of built-in modules with delegation
- objmodule: workaround for MSVC with no module delegation
- mpconfig: enable module delegation if sys needs it
- modsys: allow sys.path to be assigned to
- mkrules.mk: automatically configure frozen options when manifest set
- parsenum: fix typo in #endif comment
- nlraarch64: fix dangerous use of input register
- makemoduledefs.py: fix declaring multiple module delegations
- makemoduledefs.py: automatically declare delegation attr functions
- lexer: allow conversion specifiers in f-strings (e.g. !r)
- mkrules.mk: allow $(AFLAGS) to set flags to $(AS)
- compile: fix async for's stack handling of iterator expression
- builtinimport: fix built-in imports when external import is disabled
- stream: add mp_stream___exit___obj that calls mp_stream_close
- runtime: always initialise sched_state in mp_init
- mpconfig: add MICROPY_PY_PLATFORM, enabled at extra features level
- gc: speed up incremental GC cycles by tracking the last used block
- gc: apply some code formatting cleanup
- gc: add new MICROPY_GC_SPLIT_HEAP_AUTO "auto grow heap" mode
- profile: remove the requirement to disable MICROPY_COMP_CONST
- mpconfig: enable SSL finalizers if finalizers are enabled
- objstr: fix `str % {}` edge case
- modstruct: support pad bytes in struct format
- dynruntime.h: implement MP_OBJ_NEW_QSTR
- modthread: return thread id from start_new_thread()
- malloc: fix DEBUG_print() args in m_realloc_maybe
- runtime: add helpers to call a general function on nlr jump callback
- parse: always free lexer even if an exception is raised
- persistentcode: always close reader even if an exception is raised
- gc: add "max new split" value in result of gc.mem_free()
- nlrx64: mark nlr_push() as naked function when possible
- mkrules.mk: don't strip binary if STRIP variable is unset
- change ifdef DEBUG_PRINT to if DEBUG_PRINT
- lexer: add missing initialisation for fstring_args_idx

extmod:
- utime_mphal: provide a general mktime function
- modutime: provide a generic time module
- machine_pwm: remove PWM_INIT and PWM_DUTY_U16_NS config options
- network_cyw43: add power management constants
- vfs_lfsx: fix offset used before range check
- extmod.mk: suppress deprecated-non-prototype warning
- moduos: move os.sync() into extmod/moduos.c
- modtimeq: remove timeq module
- btstack: add cmake support for BTstack
- btstack: fix marking of static addresses in set_random_address
- asyncio: rename uasyncio to asyncio
- asyncio/uasyncio.py: add backwards-compatible uasyncio alias
- modbinascii: fix buffer length error
- update to support mbedtls 3.x
- modplatform: set MICROPY_PLATFORM_ARCH on riscv platforms
- modbtree: undefine queue macros before including berkeley-db
- modssl: add SSLContext class
- moddeflate: add deflate module providing the DeflateIO class
- modssl_mbedtls: reference SSLContext from SSLSocket
- vfs_posix_file: add poll support for missing ERR,HUP,NVAL values
- modselect: abstract out a poll_set_t struct and functions
- modselect: factor low-level polling code into common function
- modselect: add optimisation to use system poll when possible
- modselect: remove undocumented support for flags arg to poll
- modssl_mbedtls: reject ioctls that are not supported
- modssl_mbedtls: fix ioctl of a socket in closed/error state
- modselect: properly track number of poll objects that are fd's
- modssl_mbedtls: clear sock member if error creating SSLSocket
- moddeflate: change default window size
- vfs_posix_file: fix flush handling on macOS
- vfs_posix_file: implement sys.std*.buffer objects
- modlwip: add support for SO_BROADCAST socket option
- modsocket: add support for SO_BROADCAST socket option
- modssl_mbedtls: call func psa_crypto_init if PSA is used
- modssl_mbedtls: ignore err ERR_SSL_RECEIVED_NEW_SESSION_TICKET
- modlwip: fix setting of IP option SOF_BROADCAST
- network_esp_hosted: add ESP-Hosted networking interface
- modssl_axtls: only close underlying socket once if it was used
- asyncio/event.py: fix ThreadSafeFlag.ioctl return
- btstack/btstack_hci_uart: trigger a poll after UART data is sent
- asyncio/stream.py: fix cancellation handling of start_server
- modnetwork: increase max hostname length to 32
- modnetwork: forward if.config(hostname) to network.hostname
- vfs_posix_file: fix flush handling in msvc builds

shared:
- upytesthelper: fix spelling of "default"
- libc/printf: fix stdout destination for putchar and puts
- tinyusb: avoid symbol clash on targets with external TinyUSB
- tinyusb: support HS endpoint sizes
- netutils/dhcpserver: reply on correct netif

drivers:
- cyw43: make the CYW43 Bluetooth HCI driver more portable
- esp-hosted: add host driver for ESP-Hosted firmware
- ninaw10/nina_bt_hci: make some minor fixes to HCI driver
- esp-hosted: fix pin IRQ
- esp-hosted: fix MTU size
- esp-hosted: add support for WiFI LED activity indicator

mpy-cross:
- allow specifying source files starting with -
- allow reading from stdin and writing to stdout
- when reading from stdin, write output to stdout
- allow specifying stdin as input without --
- fix source file name in file-not-found error

lib:
- mbedtls_errors: update error list for current version of mbedtls
- mbedtls: update to mbedtls v2.28.1
- mbedtls_errors: add esp32-specific mbedtls error file
- mbedtls_errors: update patch and error list for new mbedtls
- mbedtls: update to mbedtls v2.28.3
- fsp: update FSP for renesas-ra to the latest version v4.4.0
- cyw43-driver: update driver to latest version v1.0.1
- btstack: update to v1.5.6.2
- pico-sdk: update to version 1.5.1
- stm32lib: update library for H5 v1.0.0
- oofatfs: fix speculative read in create_name
- uzlib: add memory-efficient, streaming LZ77 compression support
- uzlib/lz77: always use separate history buffer
- uzlib/defl_static: implement some code size improvements
- uzlib: clean up tinf -> uzlib rename
- uzlib: combine zlib/gzip header parsing to allow auto-detect
- uzlib/tinflate: implement more compact lookup tables
- uzlib/defl_static: optimize zlib_start/finish_block
- uzlib: add a source_read_data var to pass to source_read_cb
- tinyusb: update to the most recent master
- protobuf-c: add protobuf-c library
- cyw43-driver: update driver to latest version v1.0.2
- micropython-lib: update submodule to latest

Support components
==================

docs:
- reference: remove double 'are' in glossary
- update the PWM examples based on recent API improvements
- samd: make use of pin names more consistent in examples
- reference/mpyfiles: add release info on v6.1
- library/espnow: update espnow docs for WLAN.config(pm=x) options
- develop/porting: add missing code to example main.c and Makefile
- reference/speed_python: remove 4-arg limit for viper
- mimxrt: add the pin-out for the Adafruit Metro M7 board
- samd: add the pin-out for the Adafruit Metro M4 Airlift board
- library/index: update built-in extension docs
- reference/packages: add GitHub repo to package example dependency
- reference/mpremote.rst: extend the mpremote guide
- library/index: update docs after umodule rename
- rename uasyncio to asyncio
- esp32: update esp32 docs based on IDF v5 changes
- library/ssl: add documentation for SSLContext
- esp32/quickref: add LAN example for WT32-ETH01 version 1.4
- library/deflate: add docs for deflate.DeflateIO
- develop/gettingstarted: clarify submodule initialization
- develop/gettingstarted: update ARM package list
- library/neopixel: change link to a micropython-lib reference
- library/platform: add docs for the platform library
- library/network: clarify network.hostname() behaviour
- esp32/tutorial: add example for pin access via registers
- library/esp32: update ESP32 idf_heap_info docs to match behaviour
- library/gc: clarify mem_alloc and mem_free only for Python heap
- conf.py: add sphinxcontrib.jquery to extensions
- add requirements.txt file with dependencies for Sphinx
- change remaining "urequests" references to "requests"

examples:
- usercmodule: add a sub-package example
- natmod: rename umodule to module
- hwapi: rename uasyncio to asyncio
- natmod/deflate: add deflate as a dynamic native module
- mark asm, pio, etc. as noqa: F821 (undefined-name)
- hwapi: add missing import for 96Boards Carbon example
- bluetooth: raise ValueError when advertising data is too large
- bluetooth: link to aioble in BLE examples
- natmod: add features4 as a class definition example
- unix/machine_bios.py: fix typo

tests:
- run-tests.py: ensure correct cwd for mpy tests
- basics: add more tests for hashing of various types
- basics: remove __index__ and __inv__ from special methods tests
- import/builtin_ext.py: add test for built-in module override
- import/import_pkg9.py: add test for subpackage attribute
- replace umodule with module everywhere
- run-multitests.py: don't allow imports from the cwd
- run-perfbench.py: don't allow imports from the cwd
- run-natmodtests.py: don't allow imports from the cwd
- float: test domain errors for more combos of args to math funcs
- rename uasyncio to asyncio
- extmod/uctypes_array_assign_le: fix buffer
- extmod/framebuf: fix buffer size issues
- extmod: add tests for ssl.SSLContext
- extmod: add test for passing cadata into ssl.wrap_socket()
- extmod: add deflate.DeflateIO tests
- extmod: add coverage tests for select module
- extmod: skip select/socket tests if they can't create UDP socket
- extmod/select_poll_eintr.py: improve robustness of test
- misc/sys_settrace_features.py: fix to run on newer CPython
- unix/mod_os: make os.system() test work on windows
- run-tests.py: capture output of stderr when running on CPython
- multi_net: increase asyncio tests timeouts
- stress/bytecode_limit.py: reverse order of cases
- float/float_format_ints.py: put power-of-10 test in separate file
- extmod/deflate_decompress.py: skip test when not enough memory
- extmod/ssl_cadata.py: skip test on axtls
- float/math_domain.py: tweak test to also pass with obj-repr-C
- extmod/vfs_fat_finaliser.py: tweak test so files are collected
- README: document ./run-internalbench.py
- run-internalbench.py: remove old CPython reference
- multi_net/ssl_cert_rsa.py: update test certificate
- extmod/asyncio_threadsafeflag.py: update for unix select

tools:
- pyboard.py: rename ProcessPtyToTerminal member "ser" to "serial"
- mpremote: remove unused import of serial
- pyboard.py: import serial.tools.list_ports
- pyboard.py: import errno to fix undefined name in PyboardError
- manifestfile.py: fix license capturing
- mpremote: add repl option to escape non-printable characters
- pydfu.py: use getattr to retrieve getargspec function
- mpremote: add `sleep` command
- mpremote: allow terminator for shortcut commands
- mpremote: add `rtc` commands to get and set the RTC
- mpremote: handle `cp` without destination
- mpremote: detach mpremote from pyboard.py
- mpremote: fix use of stdout_write_bytes function
- mpremote: fix exec_ -> exec in commands.py
- autobuild: update auto-build code to build esp32 port with IDF v5
- autobuild: add support for application .bin files for esp32
- mpy-tool.py: use isinstance() for type checking
- codeformat.py: skip formatting ESP-IDF managed components
- codeformat.py: use pyproject.toml for black config
- mpremote: make soft-reset count as an action
- autobuild: automatically build all variants for each board
- mpy_ld.py: pre-declare some local variables to appease linter
- mpy-tool.py: ignore linter failure in Python 2 compatibility code
- mpy_ld.py: support more complex rodata sections
- metrics.py: fix nrf and rp2 board names after renaming
- autobuild: include .bin firmware in renesas-ra build output
- autobuild/build-downloads.py: verify standard features
- mpremote: add support for rfc2217, serial over TCP
- metrics.py: fix esp32 and esp8266 board names after renaming
- change remaining "urequests" references to "requests"

CI:
- ci.sh: build both SAMD21 and SAMD51 boards as part of samd CI
- ci.sh: add functions to check code spelling using codespell
- ci.sh: add mimxrt and samd ports to code size build
- ci.sh: build PICO_W board as part of rp2 CI
- ci.sh: add a H5 board to stm32 CI build
- ci.sh: add ARDUINO_PORTENTA_C33 to RA CI build
- workflows: fetch full history for mpremote workflow
- workflows: add spell check to code formatting workflow
- workflows: add GitHub Action to lint Python code with ruff
- workflows: force use of Ubuntu-20.04 for unix 32-bit builds
- workflows: update esp32 CI to use IDF v5.0
- workflows: bump actions/checkout from 3 to 4

The ports
=========

all ports:
- use extmod version of mktime instead of port-specific one
- remove os.sync() implementation from stm32 and renesas-ra
- enable os.sync() for esp32, esp8266, rp2, mimxrt, samd51
- standardise docs link in help text
- in machine_i2s.c, rename uasyncio to asyncio
- simplify board feature tags in board.json
- */boards/*/board.json: remove "id" field
- restrict board.json to standard features
- rename Arduino board LED pins to be consistent

bare-arm port: no changes specific to this component/port

cc3200 port:
- mods/modutime: use extmod version of time module
- tools: fix exception raised on process failure
- Makefile: build firmware.zip

embed port: no changes specific to this component/port

esp8266 port:
- modutime: use extmod version of time module
- add support for the Espressif ESP-NOW protocol
- machine_pwm: implement duty_u16() and duty_ns() for consistency
- add support to set/get power saving mode of WLAN
- change network.WLAN from a function to a type
- allow Ctrl-C to interrupt the corrupt-fs while loop
- machine_pin: accept an integer argument to mp_obj_get_pin_obj
- add board variant support
- boards/ESP8266_GENERIC: add image filename
- boards: make sure modespnow.o is placed in irom0
- boards/ESP8266_GENERIC: remove urllib from the 2MiB manifest

esp32 port:
- modutime: use extmod version of time module
- add support for the Espressif ESP-NOW protocol
- add support to set/get power saving mode of WLAN
- change network.WLAN from a function to a type
- boards: add some missing board configs for two UM boards
- esp32_ulp: enable FSM ULP for S2 and S3 chips
- uart: use xtal as UART clock source on S3 and C3
- modespnow: change name of buffer size config option to "rxbuf"
- CMake: change PROJECT_DIR to CMAKE_CURRENT_LIST_DIR
- esp32_ulp: fix ULP (FSM) support for S2 and S3
- allow Ctrl-C to interrupt the corrupt-fs while loop
- switch from UART driver to UART HAL
- ppp_set_auth: add pppapi_set_auth from ESP-IDF
- modesp32: remove esp32.hall_sensor function
- update port to support IDF v5.0.2
- in recv_cb, get espnow rssi from recv_info->rx_ctrl
- network_wlan: wait for WIFI_EVENT_STA_START after activating
- Makefile: provide more IDF shortcuts
- boards: change SDK config parameters from deprecated to new ones
- modules/inisetup.py: format partition as FAT if its label is ffat
- machine_uart: always select a source_clk value in UART config
- re-enable mDNS after move to IDF v5.0.2
- boards/GENERIC_OTA: enable silent checks to reduce firmware size
- network_wlan: wait for STA/AP START/STOP event in wlan.active
- machine_timer: switch from legacy driver to timer HAL
- machine_pin: add a pin-find func and use it in machine_pin_get_id
- use always machine_pin_get_id for getting a Pin id
- add support for board-named pins and the Pin.board dict
- collect properties from IDF-managed components as well
- modmachine: add generic machine.bootloader()
- usb: add custom TinyUSB callback support
- boards/ARDUINO_NANO_ESP32: add support for Arduino Nano ESP32
- CMakeLists: enable multiple extra component directories in build
- boards/ARDUINO_NANO_ESP32: fix deploy instructions
- main: remove unused mbedtls debug function
- machine_wdt: allow feeding WDT from threads
- machine_hw_spi: fix access of SPI(2)
- machine_hw_spi: remove unnecessary duplicate SPI pin defaults
- machine_hw_spi: remove SPI host renaming for C3 and S3 variants
- machine_hw_spi: check for valid SPI id in constructor, not init
- boards: remove references to the IDF version in board.md files
- README: specify that only IDF v5.0.2 is supported
- allow malloc() to allocate from SPIRAM
- enable automatic Python heap growth
- gccollect: make level arg volatile to force recursive function
- Makefile: implement `make submodules` to match other ports
- boards/GENERIC: merge with GENERIC_{SPIRAM,OTA,D2WD,UNICORE}
- boards/GENERIC_C3: merge with GENERIC_C3_USB
- boards/GENERIC_S2: merge with ESP32_S2_WROVER
- boards/GENERIC_S3: merge with GENERIC_S3_{SPIRAM,SPIRAM_OCT}
- partitions.csv: rename to partitions-4MiB.csv
- use uppercase variant names
- Makefile: append board variant to BUILD
- rename GENERIC* boards to ESP32_GENERIC*
- boards/ESP32_GENERIC_C3: enable UART REPL
- modsocket: add support for SO_BROADCAST socket option
- modnetwork: add support for SO_BINDTODEVICE socket option
- support JTAG console, free up UART
- machine_uart: release GIL for blocking reads
- boards: add pins.csv to UM boards and other minor changes
- boards/UM_NANOS3: add new UM NanoS3 board
- network_ppp: block after deleting task
- boards/ARDUINO_NANO_ESP32: clarify recovery instructions
- boards/UM_FEATHERS3: fix I2C pins in pins.csv
- skip validation of image on boot from deepsleep
- machine_pin: fix null pointer access in machine_pin_find
- mphalport: add function/line/file info to check_esp_err exception
- fix Partition.writeblocks() partial write corruption
- boards: fix VBAT voltage calculation for UM S3 boards
- boards: add bootloader rollback support for all builds
- main: allow a board to override the MicroPython task stack size
- boards/ARDUINO_NANO_ESP32: use Arduino USB IDs
- boards/manifest.py: freeze aioespnow into firmware by default

mimxrt port:
- modutime: use extmod version of time module
- machine_pwm: start PWM only if freq and duty are set
- flash: separate low level driver code from flash object
- mpconfigport: add back lost uos.urandom()
- add missing UART defintion and remove obsolete config
- machine_spi: ignore transfers with len=0
- machine_pin: perform full configuration in machine_pin_set_mode
- sdcard: fix GCC 13 build error with sdcard_cmd_set_bus_width
- led: add support for up to four LEDs
- boards/ADAFRUIT_METRO_M7: add Adafruit Metro M7 board definition
- machine_pwm: fix freq change, PWM print, and error checks
- Makefile: use a specific fsl_flexspi_nor_boot.c for mimxrt1062
- machine_pin: fix bug when Pin.irq is called without a handler
- hal/pwm_backport: fix 0 and 65536 edge cases of PWM's duty_u16
- machine_uart: add uart.deinit method and machine_uart_deinit_all
- machine_uart: add support for UART hardware flow control
- boards: add support for GPIO control of SNVS pins
- hal: make flash clock frequency configurable
- fix UART RTS/CTS assignments for the OLIMEX and Adafruit boards
- machine_pin: extend pin configuration functions
- sdio: add SDIO driver
- integrate support for WiFi via the CYW43 driver
- integrate Bluetooth support with NimBLE bindings
- irq: move all IRQ related definitions to dedicated header
- machine_uart: fix and complete UART.deinit and uart_deinit_all
- boards: fix use of MICROPY_HW_SDRAM_AVAIL in MIMXRT1176.ld
- machine_uart: support slow baud rates for UART
- machine_uart: add a helper function to change the baudrate
- sdio: move config guard so headers are only included if used
- Makefile: update to work with latest TinyUSB
- mpconfigport: don't override parse chunk alloc
- sdio: add support for the 117x series
- mimxrt_sdram: allow boards to override the default SDRAM config
- Makefile: enable the FSL USDHC for supported MCU series
- remove SDCARD Makefile config option
- mpbthciport: enable flow control for BT HCI UART
- mbedtls: enable certificate validity time validation
- machine_uart: set the UART clock to a fixed 40MHz value
- boards/MIMXRT1176_clock_config: fix comments about UART clocks
- boards: fix naming of SD-card config option
- mpbthciport: allow disabling UART flow control for BLE
- machine_rtc: improve the RTC init at boot

minimal port: no changes specific to this component/port

nrf port:
- modules/utime: use extmod version of time module
- boards: rename all nRF boards to use uppercase

pic16bit port: no changes specific to this component/port

powerpc port:
- mpconfigport: don't override parse chunk alloc

qemu-arm port: no changes specific to this component/port

renesas-ra port:
- change MICROPY_HW_BOARD_NAME definition to product name
- modutime: use extmod version of time module
- update boards and ra directory files to support FSP v4.4.0
- add a macro definition to avoid compile error of FSP v4.4.0
- irq: fix typo in comment about IRQ priorities
- consolidate hal_entry.c code and remove hal_entry() func
- boards/make-pins.py: fix PA/PB pins support
- consolidate all fsp_cfg header files to one location
- support changing baudrate for UART
- add support for RA6M5, and add machine PWM, DAC, SDCard
- boards/VK_RA6M5: add new board definition
- remove duplicate machine module from constants list
- machine_spi: consistently use machine_pin_find to get pin
- boards: remove unreachable code in make-pins.py
- Makefile: generate binary firmware output
- add TinyUSB support
- add Bluetooth support using NimBLE
- add RNG driver
- add networking support using lwIP
- add mbedTLS support
- fsp_cfg: add common FSP config files
- boards/ARDUINO_PORTENTA_C33: add support for Portenta C33
- boards/ARDUINO_PORTENTA_C33: update WiFi config
- tune lwip buffers and timing to improve network performance

rp2 port:
- modutime: use extmod version of time module
- machine_pwm: enable keyword args in constructor and add init method
- machine_pwm: add support for inverting a PWM channel output
- machine_pwm: add duty_x() checks and return 0 if PWM is not started
- make rp2_state_machine_exec accept integers
- CMakeLists: allow relative MICROPY_BOARD_DIR when invoking cmake
- mphalport: only use CYW43 MAC for WLAN0 interface
- CMake: normalize MICROPY_PORT_DIR
- add Bluetooth support via cyw43
- mpbthciport: cancel existing alarms
- boards/PICO_W: enable Bluetooth Low Energy support
- machine_pin: factor out pin-find code from machine_pin_make_new
- use uppercase variant names
- Makefile: append board variant to BUILD
- rename PICO, PICO_W to RPI_PICO, RPI_PICO_W
- machine_timer: fix printing of timer period
- mpbthciport: switch to static scheduler nodes
- mpbthciport: fix HCI UART config
- mpconfigport: disable BLE locking when MICROPY_PY_BLUETOOTH enabled
- boards/ARDUINO_NANO_RP2040_CONNECT: use standard HCI UART baudrate
- modmachine: fix lightsleep while wifi is powered off
- msc_disk: allow configuring the USB MSC inquiry response
- README: fix name of RPI_PICO_W board
- CMakeLists: enable debug symbols in all builds
- implement time.time_ns with time_us_64 so it has us resolution

samd port:
- modutime: use extmod version of time module
- machine_pwm: add init() method to PWM and simplify the PWM code
- mpconfigport: drop support for SoftSPI max speed
- boards/MINISAM_M4: update pins.csv for the Mini SAM M4 board
- rearrange the MCU-specific loader files
- mcu/samd51: enable MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
- boards: add default deploy instructions
- main: fix sercom deinit ordering in soft-reset
- modmachine: add machine.deepsleep as alias of machine.lightsleep
- modmachine: make some machine classes configurable by #defines
- boards/SEEED_WIO_TERMINAL: rename two pins starting with a digit
- mcu: reduce the startup time after hard reset
- machine_uart: add support for UART hardware flow control
- boards/ADAFRUIT_METRO_M4_EXPRESS: add Metro M4 Express Airlift
- boards: rename flash pins consistently for QSPI and SPI
- samd_spiflash: add SPI flash driver and configure it accordingly
- samd_qspiflash: add QSPI flash driver and configure it accordingly
- adapt existing samd.Flash and integrate with (Q)SPI flash in boot
- boards: extend the code size limit for boards with external flash
- set the LFS type in mpconfigmcu.mk instead of mpconfigboard.mk
- Makefile: move the math lib files from mpconfigmcu.mk to Makefile
- Makefile: print memory region usage instead of totals
- mpconfigport: enable DHT and onewire drivers on all MCUs/boards
- mpconfigport: provide the platform module
- modules/_boot.py: add /lib to sys.path
- mpconfigport: don't override parse chunk alloc

stm32 port:
- modutime: use extmod version of time module
- boards/ARDUINO_PORTENTA_H7: enable FDCAN
- boards/stm32h723_af.csv: fix ADC AF definitions
- mboot: fix alignment of packed final buffer
- irq: fix typo in comment about priorities
- usb: fix USB support on STM32G4
- boards/NUCLEO_G474RE: make it easier to enable USB
- adc: add support for STM32L4A6 MCUs
- boards/NUCLEO_L4A6ZG: add new board definition
- help: don't include unavailable features in help()
- help: exclude legacy entries from help, and adjust constant names
- mpconfigboard_common: provide default spidev config
- boards: use default spibdev config where appropriate
- Makefile: pass relevant CPU flags to assembler
- make-stmconst.py: support structs with names ending in _t
- main: start UART REPL as early as possible
- usbd_conf: treat G0 USB periph as MICROPY_HW_USB_IS_MULTI_OTG=0
- machine_adc: handle ADC resolution less than 8 bits on all MCUs
- add initial support for H5 MCUs
- boards: add ld, af.csv and hal_conf_base.h files for H5 MCUs
- octospi: add preliminary support for OCTOSPI peripheral
- boards/STM32H573I_DK: add H5 board definition files
- add USB support for STM32L1 MCUs
- modify RCC->APB2ENR directly instead of HAL API
- modmachine: remove duplicate machine_timer_type declaration
- modmachine: make machine_reset_cause_obj public
- dac: fix dac.write_timed on G4 MCUs to use 32-bit DMA access
- adc: fix ADC clock prescaler for G4 MCUs
- adc: fix pyb.ADCAll.read_core_temp for G4 MCUs
- adc: fix reading internal ADC channels on G4 MCUs
- machine_adc: fix machine.ADC to work on G4 MCUs
- adc: add workaround for ADC errata with G4 MCUs
- adc: fix pyb.ADCAll.read_core_bat on G4 and L4 MCUs
- qspi: allow qspi_write_cmd_data to write cmd with 1 data byte
- mpconfigport: always define MICROPY_SOFT_TIMER_TICKS_MS
- remove duplicate machine module from constants list
- boards/B_L072Z_LRWAN1: add pin definitions for internal SX1262
- boards/B_L072Z_LRWAN1: lower default ROM level to "Core"
- spi: add STM32WL5 SUBGHZ SPI peripheral
- powerctrlboot: support STM32WL system clock from HSE+PLL
- dma: fix DMA completion on WL55 boards
- subghz: add STM32WL55 subghz radio interface to stm module
- modstm: add MICROPY_PY_STM_CONST flag, clear it for STM32WL5
- use uppercase variant names
- Makefile: append board variant to BUILD
- mboot: fix fwupdate by replacing zlib with new deflate module
- uart: fix UART timeout issue with low baudrate on G4 MCUs
- timer: fix deadtime config on Advanced Timer peripherals
- dma: add support for SPI1 DMA on H5 MCU's
- octospi: add support for dual-line SPI interface
- powerctrlboot: allow using PLL3 for USB clock on H5 MCU's
- timer: fix use of TIM8 on H5 MCU's
- uart: add support for UART10 when it's a USART
- powerctrlboot: allow PLL1 Q and R outputs to be enabled on H5
- adc: fix STM32H5 support
- adc: add support for STM32H5 ADC2 inputs
- adc: optimize sampling time for G4, H5, L4 and WB MCUs
- machine_adc: fix and improve STM32H5 support
- dac: add STM32H5 DAC support, with dma_nohal implementation
- boards: move includes to after defines in all hal_conf.h files
- uart: generalise UART source clock calculation for H5 and H7 MCUs
- dma: remove unbalanced )
- usbd_msc_interface: allow configuring the MSC inquiry response
- boards/ARDUINO_GIGA: update board config
- i2c: add support for I2C4 on H7 MCUs

teensy port: no changes specific to this component/port

unix port:
- modutime: use extmod version of time module
- Makefile: allow variants to add QSTR_DEFS
- main: add NLR scope for checking module __path__
- README: fix Markdown link markup
- modsocket: add poll support for missing ERR,HUP,NVAL poll values
- modselect: remove unix-specific implementation of select module
- modjni: fix build errors with type definitions and error strings
- main: fix memory leakage if MICROPY_USE_READLINE is disabled

webassembly port:
- modutime: use extmod version of time module
- make mp_js_do_str asynchronous
- make mp_js_process_char asynchronous
- replace typeof window check with ENVIRONMENT_IS_NODE flag

windows port:
- Makefile: allow variants to add QSTR_DEFS

zephyr port:
- modutime: use extmod version of time module

New mip package manager, compressed type structs and Pico W support

This release of MicroPython introduces a new lightweight package manager
called mip, which uses a custom protocol to query and install packages that
is optimised for embedded systems.  It is intended to take over the role of
upip and supports installing packages from micropython-lib as well as any
URL.  Mip can be run directly on a device (with network connectivity) or
via mpremote.  As part of this, all pure-Python drivers have been moved
from the micropython repository to the micropython-lib repository, making
it easier to install the packages needed for a given project.

In the MicroPython runtime, core/built-in types have been compressed by
only including in the C-level type struct as many slots for C function
pointers as is needed for a given type (instead of storing NULL pointers
for unused slots).  This resulted in a reduction of code size of many
kilobytes for all ports (eg around 1200 for bare-arm) with a very minimal
loss in performance.  Any third-party C extensions will need to be updated
to work with this change.  See commits
662b9761b37b054f08fe2f7c00d0fce3a418d0b0 and
3ac8b5851e5f4dade465d52b91ed2ccc17851263 for details.

The MicroPython VM/runtime has also seen many improvements and bug fixes,
including: addition of hex/fromhex methods to bytes/memoryview/bytearray,
dictionary union (PEP 584), support for __float__ and __complex__
functions, support for __dict__ on module objects and UTF-8 validation of
all strings.  Whole number floats are now formatted exactly, and there have
been other accuracy improvements to parsing and formatting of floats.
A sub-version has been introduced for .mpy files which is used only when a
.mpy file includes native code, allowing the native ABI to change while
retaining backwards compatibility with pure bytecode .mpy files.
There is now an option to have the GC heap split across more than one pool
of memory, although this is not yet in use by the ports.  And root pointer
registration has been simplified with the new MP_REGISTER_ROOT_POINTER
macro.

In the network module, the keyword arguments to scan(), connect() and
config() have been renamed to be more consistent across ports and drivers.
The changed argument names are: "essid" changed to "ssid", "auth" or
"authmode" changed to "security", and "password" changed to "key".  The old
keyword arguments are still supported so this change is backwards
compatible.  The functions network.hostname() and network.country() have
also been added and provide a standard interface across ports to set the
global networking configuration for all interfaces and interface types.  In
particular, setting the hostname is now supported for all CYW43xx-based
boards (pyboard-D, Arduino Portenta, Pico W, and others).

The mbedtls (SSL library) settings have also been unified across ports that
use this library and enable elliptic curve DH and DSA cryptography enabled
so that devices can connect to more websites.  The cert_reqs and cadata
arguments have also been implemented.  Sockets now support leaving
multicast groups.  WebREPL will now run the page from the device, allowing
WebREPL resources to load from a HTTPS site.

The bluetooth module has a minor breaking change for
IRQ_GATTC_CHARACTERISTIC_RESULT: def_handle has been replaced with
end_handle.  This is not expected to affect most programs as def_handle is
unlikely to be used.  See commit cacc96d98c2a70dc7e5194331ea70746c39746ec.

The uasyncio module now supports stream read(-1), handles gather with no
awaitables, and adds a clear() method to ThreadSafeFlag.  The framebuf
module adds ellipse and polygon drawing methods, and a fill argument to
rect() for consistency with those new methods.

A new port has been added, the "embed" port, which is a port of MicroPython
that targets the C language and outputs a set of self-contained .c and .h
files for embedding into a wider project.  An example is provided to show
how this works.

The esp8266 port has reverse-special-methods enabled on the GENERIC board,
uart.flush() and uart.txdone() added, real open drain output enabled on
pins driven by PWM, and adds the ability to set TX power for the WLAN
interface.

The esp32 port now uses synchronous BLE events which allows support for BLE
pairing and bonding.  The LAN driver adds support for LAN8710, KSZ8081,
configuration of ETH ref_clk pin, and support for SPI-based Ethernet chips.
UART now supports setting timeout_char and implements uart.flush() and
uart.txdone().  New boards include ESP32S3 with octal SPIRAM, Olimex PoE
boards and a generic board for unicore chips.  There have also been many
bug fixes, in particular for newer MCU versions such as S2, S3 and C3.

The mimxrt port has seen a lot of clean up of the code, support for
MIMXRT1176 MCUs and the MIMXRT1170_EVK board, a soft-timer implementation
of machine.Timer, addition of machine.bootloader(), as well as uart.flush()
and uart.txdone().

On the nrf port, machine.UART and machine.PWM have been improved to match
other ports (the PWM change is a breaking change), and machine.I2C now
supports the freq argument.  New boards include the Arduino Nano 33 BLE
sense board and the Seeed XIAO NRF52840 Sense.

The rp2 port sees the integration of the CYW43xx WiFi driver which is used
in the new Pico W board, a board similar to the Pico but with WiFi support.
Other new boards include W5500_EVB_PICO, WEACTSTUDIO and the nullbits Bit-C
PRO board.  Support has been added for named pins, including Pin.board and
Pin.cpu attributes, consistent with other ports that support this feature.
The machine.lightsleep() function has been implemented, along with SSL
certificate time validation, and more accurate formulas are used to
determine PWM frequency and duty.  The GC heap available to MicroPython
programs has been increased to use the maximum available free RAM, adding
about 20k to the user heap.  There have also been important bug fixes to
threading and concurrency when using both cores.

The samd port has been significantly extended to include: named pins with
a pins.csv file, and Pin.board and Pin.cpu attributes; ADC, PWM, DAC,
SoftSPI, SoftI2C, SPI, I2C and RTC classes added to the machine module;
pin.irq() method and OPEN_DRAIN mode for pins; freq, disable_irq,
enable_irq, idle, lightsleep and time_pulse_us functions added to the
machine module.  Floating point support has been added for SAMD21 devices,
and the math module enabled for SAMD51.  A board definition for Sparkfun
Think Plus has been added.

The stm32 port sees support added for STM32L1xx MCUs, STM32H723, USB on
STM32G0xx and mboot support for STM32G0xx.  The existing CYW43xx WiFi
driver has been replaced with the open-source version of cyw43-driver and
this has been integrated with all existing boards with CYW43xx chips.
Support for the CC3000 WiFi driver has been removed, and the Wiznet driver
integration has been reworked to use the generic one shared with other
ports (and also uses lib/wiznet5k instead of the old drivers/wiznet5k).
Hardware I2C implementation has been added for STM32L1xx and STM32L4xx,
support added for Arduino 1200bps touch to enter the bootloader (only on
Arduino boards), mbedtls (SSL) certificate time validation added, and
link-time-optimisation (LTO) enabled by default on boards with small flash
size.  New board definitions include: LEGO Hub No. 7, NUCLEO-L152RE,
NUCLEO-F756ZG, NUCLEO-H723ZG, Arduino Nicla Vision and Arduino Giga H7.
Arduino boards also now include a range of frozen libraries including
senml.

For the unix and windows ports, build outputs (including executables) are
now kept inside the $(BUILD) directory associated with the build.  As part
of this the variant suffix has been removed from the executable name.  For
example, what was micropython-coverage is now build-coverage/micropython,
and the standard variant is build-standard/micropython.  Furthermore, the
dev variant has been removed and its features enabled instead on the
standard variant, which now enables the same feature set as a typical
bare-metal board, making it more convenient to use for development.  The
remaining variants are: minimal, standard, nanbox, coverage.  The SSL
implementation for this port has switched from axtls to mbedtls, again to
match most bare-metal ports.

The javascript port has been renamed to the webassembly port, and adds
support for VFS and VfsPosix using Emscripten's POSIX filesystem layer.
The way stdout printing works has also changed to dispatch via a custom
event called "micropython-print".

The zephyr port upgraded Zephyr to v3.1.0, added custom configuration for
bbc_microbit_v2, and enabled finalisers.

The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):

       bare-arm:   -1124  -1.934%
    minimal x86:   -4322  -2.967%
       unix x64: +264181 +50.533% standard
          stm32:   -3592  -0.906% PYBV10
         cc3200:   -1832  -0.990%
        esp8266:   -2284  -0.327% GENERIC
          esp32:   +9659  +0.632% GENERIC
            nrf:     -84  -0.045% pca10040
            rp2:  +13096  +4.291% PICO
           samd: +127776 +90.488% ADAFRUIT_ITSYBITSY_M4_EXPRESS

The changes that dominate these numbers are:
- bare-arm, minimal, stm32, cc3200, esp8266: reduced size due to compressed
  type structs
- unix: switching axtls for mbedtls, merging in dev configuration options
  and features
- esp32: new Ethernet drivers and some additional machine module
  functionality
- nrf: compressed type struct and machine module improvements
- rp2: additional mbedtls features and ciphers
- samd: many new features, and machine module classes and functions

Thanks to everyone who contributed to this release:
Alex Riesen, Andrew Leech, Andrew Scheller, Angus Gratton, Antonello
Margottini, Antonin ENFRUN, Ayke van Laethem, Blake Felt, brave ulysses,
Brian Cooke, Brian Pugh, Carlosgg, Chris Overgaauw, Chris Swan, Chris
Waggoner, chrismas9, Christian Clauss, Christian Walther, Clayton Cronk,
cpottle9, Dale Weber, Damiano Mazzella, Damien George, Damien Tournoud, Dan
Ellis, Daniel Jour, David (Pololu), David Grayson, David Lechner, David
Peake, David Yang, Dorukyum, Efi Weiss, enriquezgarc, Felix Dörre, Florian
Weimer, glenn20, hoihu, Howard Lovatt, iabdalkader, Ian Davies,
IcedRooibos, Ihor Nehrutsa, Jacob Siverskog, Jan Hrudka, Jan Willeke, Jared
Hancock, Jatty_, Jay Greco, Jeff Epler, Jeremy Rand, Jim Mussared, Jonas
Scharpf, Jos Verlinde, Juan Francisco Cantero Hurtado, Koen De
Vleeschauwer, Kyuchumimo, Lars Haulin, Laurens Valk, LiaoJingyi_winY7kp,
Luiz Brandao, ma-lalonde, manobendro, Maripo GODA, Mark Grosen, Martin
Milata, Mat Booth, Matt Trentini, Maureen Helm, Michael Bentley, Michael
Mogenson, MrJake222, Nathan Hendler, Ned Konz, Nicholas H.Tollervey, Oliver
Joos, omogenot, Patrick, Patrick Joy, Paul Grayson, Paul Warren, Pepijn de
Vos, Peter Harper, Peter Hinch, PGE, Phil Howard, Philip Peitsch, Philipp
Ebensberger, pmendham, Rayane Chatrieux, Red_M, Rob Knegjens, robert-hh,
Sebastian Romero, Simon Arlott, Sky, Stewart C. Russell, Stig Bjørlykke,
stijn, Stuart Langridge, Takeo Takahashi, Thorsten von Eicken, Tim Gates,
Tobias Thyrrestrup, Tomasz 'CeDeROM' CEDRO, Tomofumi Inoue, TPReal,
Trammell hudson, Wind-stormger, yn386, Yonatan Goldschmidt, 小权一句两句.

The work done in this release was funded in part through GitHub Sponsors,
by George Robotics, and by Planet Innovation.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- fix paths to mpy-cross and micropython binaries
- remove MICROPY_PY_IO_FILEIO config option
- update all manifest.py files to use new features
- simplify buffer protocol to just a "get buffer" callback
- standardise mp_obj_type_t initialisation
- make all mp_obj_type_t defs use MP_DEFINE_CONST_OBJ_TYPE
- fix #if inside MP_DEFINE_CONST_OBJ_TYPE for msvc
- remove unnecessary locals_dict cast
- use += rather than = everywhere for CFLAGS/LDFLAGS/LIBS
- keep msvc build output in build/ directories
- fix Python comparison to None and True, and use "not in"
- use micropython-lib unconditionally in manifests
- replace upip with mip everywhere
- update Python formatting to black "2023 stable style"
- update copyright year range to include 2023

py core:
- vm: change comparison for finally handler search from > to >=
- emit: remove logic to detect last-emit-was-return-value
- emit: suppress unreachable bytecode/native code that follows jump
- objcell: make cell get/set funcs static-inline to reduce code size
- parsenum: support parsing complex numbers of the form "a+bj"
- parsenum: fix parsing of complex "j" and also "nanj", "infj"
- parsenum: optimise when building with complex disabled
- objclosure: forward function attributes for closures
- objfun: support function attributes on native functions
- builtin: remove unnecessary module declarations
- builtinhelp: don't show help for an MP_MODULE_ATTR_DELEGATION_ENTRY
- mkrules.cmake: improve printing of git-submodules error
- scheduler: de-inline and fix race with pending exception / scheduler
- vm: document internal SELECTIVE_EXC_IP option
- emitnative: fix STORE_ATTR viper code-gen when value is not a pyobj
- vm: remove check for ip being NULL when handling StopIteration
- vm: in YIELD_FROM opcode, expand helper macros and remove them
- vm: consistently indent #if guards to match the code they surround
- objnamedtuple: fix segfault with empty namedtuple
- misc: add MP_STATIC_ASSERT_NOT_MSC()
- obj: add static safety checks to mp_obj_is_type()
- obj: add debug-only runtime checks to mp_obj_is_type()
- make_root_pointers: add MP_REGISTER_ROOT_POINTER parser/generator
- mpstate: drop MICROPY_PORT_ROOT_POINTERS from mp_state_vm_t
- persistentcode: use MP_REGISTER_ROOT_POINTER()
- modsys: use MP_REGISTER_ROOT_POINTER()
- scheduler: use MP_REGISTER_ROOT_POINTER()
- misc: fix msvc compilation with compressed error messages
- qstr: make mp_decompress_rom_string decl and def the same
- gc: allow the GC heap to be split over multiple memory areas
- gc: reduce code size when MICROPY_GC_SPLIT_HEAP is disabled
- obj: add support for __float__ and __complex__ functions
- obj: make mp_obj_get_complex_maybe call mp_obj_get_float_maybe first
- compile: support large integers in inline-asm data directive
- modio: remove FileIO and TextIOWrapper from io module
- formatfloat: format all whole-number floats exactly
- builtinimport: remove duplicate static function argument
- mkenv.mk: use micropython-lib from submodule by default
- runtime: fix crash in star arg unpacking
- mpprint: fix formatting typo with mp_print_ext_t struct name
- objstr: reformat str access macros to make them readable
- mkrules.mk: keep all build artefacts inside $(BUILD) directory
- dynruntime.mk: allow building assembly source in natmods
- nlrpowerpc: fix generation of ppc64 code on ppc32 build
- qstr: change qstr hash type from mp_uint_t to size_t
- objstr: consolidate methods for str/bytes/bytearray/array
- objstr: add hex/fromhex to bytes/memoryview/bytearray
- objstr: remove str function object declarations from header file
- mkrules: use abspath to find directory for mpy-cross dependency
- parsenum: ensure that trailing zeros lead to identical results
- formatfloat: use pow(10, e) instead of pos/neg_pow lookup tables
- dynruntime: add mp_obj_is_true
- clean up formatting of union definitions
- builtinimport: allow overriding of mp_builtin___import__
- objstr: split mp_obj_str_from_vstr into bytes/str versions
- objstr: always ensure mp_obj_str_from_vstr is unicode-safe
- objstr: optimise mp_obj_new_str_from_vstr for known-safe strings
- objstr: always validate utf-8 for mp_obj_new_str
- persistentcode: clarify ValueError when native emitter disabled
- objpolyiter: add a new polyiter type with finaliser support
- mpconfig: add LFS1/LFS2 options to match FAT/posix
- mpconfig: make feature levels available to mpconfigport.h
- mpconfig: add "everything" features from unix coverage
- objpolyiter: fix comment about finaliser method
- mkrules.mk: add link to build troubleshooting on failure
- obj: add macro to declare ROM mp_obj_type_t instances
- objexcept: make MP_DEFINE_EXCEPTION use MP_DEFINE_CONST_OBJ_TYPE
- obj: add "full" and "empty" non-variable-length mp_obj_type_t
- obj: add accessors for type slots and use everywhere
- obj: add slot-index mp_obj_type_t representation
- obj: remove basic mp_obj_type_t sparse representation
- objtype: optimise slot RAM usage for instance types
- objnamedtuple: optimise slot RAM usage for namedtuple
- obj: merge getiter and iternext mp_obj_type_t slots
- obj: convert make_new into a mp_obj_type_t slot
- obj: optimise code size and performance for make_new as a slot
- persistentcode: introduce .mpy sub-version
- objmodule: add support for __dict__
- runtime: add mp_raise_OSError_with_filename helper function
- include filename in errors from loading/saving files via "open"
- parse: allow const types other than int to optimise as true/false
- objstr: don't treat bytes as unicode in str.count
- mkenv.mk: make CPP definition explicit for consistency
- objstr: add a helper to set mp_obj_str_t data
- modsys: add support for sys.executable
- py.mk: make user-C-module handling self-contained in py.mk
- misc: remove use of bitfield from vstr_t
- obj: verify floating point type is correct for repr C
- persistentcode: only emit sub-version if generated code has native
- obj: add comments explaining the slot index scheme
- makeversionhdr: fall back to py/mpconfig.h instead of docs/conf.py
- builtinimport: fix crash handling "weak link" module names
- objarray: detect bytearray(str) without an encoding
- emitnative: ensure load_subscr does not clobber existing REG_ARG_2
- nlrmips: add native NLR support for MIPS architecture
- makeversionhdr.py: allow running outside of repo
- objdict: implement dictionary union (PEP 584)
- bc: fix checking for duplicate **kwargs
- modmicropython: make module optional
- mpconfig: include micropython module in core features
- remove the word "yet" from exception messages
- pass in address to compiled module instead of returning it
- gc: avoid valgrind false positives
- gc: ensure a gap of one byte after the ATB
- gc: fix debug printing of GC layout
- obj: remove unused MP_DEFINE_CONST_OBJ_FULL_TYPE macro
- emitnative: initialise locals as Python object type for native code
- map: clear value when re-using slot with ordered dictionaries
- gc: increase the address length in gc_dump_alloc_table()
- objarray: raise error on out-of-bound memoryview slice start
- lexer: wrap in parenthesis all f-string arguments passed to format
- add parenthesis to default impl of MP_OBJ_TO_PTR, MP_OBJ_FROM_PTR
- objint_mpz: catch and reject @ and @= operating on big integers
- mkrules: support mpy-tool-flags in cmake frozen code generation
- mkrules.cmake: force build mpversion.h and frozen_content.c
- modmath: fix two-argument math function domain check
- emitnative: explicitly compare comparison ops in binary_op emitter
- makeversionhdr.py: optionally get git tag and git hash from env vars
- compile: fix scope of assignment expression target in comprehensions
- gc: make gc_dump_info/gc_dump_alloc_table take a printer as argument
- mpconfig: provide config option for internal printf printer
- builtinimport: fix unix port build with external imports disabled
- makeversionhdr.py: always add micro to version string even if it's 0
- obj: add MP_NOINLINE to mp_obj_malloc_helper
- mpstate: add mp_thread_is_main_thread() helper macro
- scheduler: implement VM abort flag and mp_sched_vm_abort()
- obj: fix spelling of staticmethod
- makeqstrdefs.py: fix handling GreenHills C/C++ preprocessor output

extmod:
- network_cyw43: rename WLAN keyword args to ssid/security/key
- network_ninaw10: rename WLAN connect argument from essid to ssid
- modlwip: clean up inclusion of modlwip in build process
- extmod.cmake: only include modbtree in build if it's enabled
- extmod.mk: separate out extmod file list from py.mk to extmod.mk
- modbtree: use buffer protocol for keys/values
- uasyncio: attempt to write immediately in Stream.write method
- uasyncio: implement stream read(-1) to read all data up to EOF
- vfs: prevent uninitialized variable warning for path_out
- network_cyw43: support new cyw43-driver
- modnetwork: include cyw43-driver header if it's enabled
- network_cyw43: add "security" config option to get/set auth mode
- btstack: use MP_REGISTER_ROOT_POINTER()
- nimble: use MP_REGISTER_ROOT_POINTER()
- modnetwork: use MP_REGISTER_ROOT_POINTER()
- uos_dupterm: use MP_REGISTER_ROOT_POINTER()
- modlwip: use MP_REGISTER_ROOT_POINTER()
- vfs: use MP_REGISTER_ROOT_POINTER()
- modbluetooth: use MP_REGISTER_ROOT_POINTER()
- always use custom mbedtls error message code
- modussl_mbedtls: implement cert_reqs and cadata arguments
- btstack: fix descriptor discovery handle range and events
- network_ninaw10: move ninaw10 root pointer registrations here
- modbluetooth: add support for running sync irq on system thread
- webrepl: allow the page to run from the device (over HTTP)
- uasyncio: handle gather with no awaitables
- ntptime: factor out ntptime module from esp8266 port
- modussl_mbedtls: set a more sensible default debug log level
- network_cyw43: add hostname config option
- network_wiznet5k: register NIC when the lwIP stack is used
- network_wiznet5k: drop obsolete argument count check
- network_wiznet5k: deinit the NIC before (re-)initialisation
- network_wiznet5k: schedule clearing of interrupt flags
- network_wiznet5k: rearrange the function wiznet5k_poll()
- network_wiznet5k: extract SPI transfer function dynamically
- uasyncio: add clear method to ThreadSafeFlag
- uasyncio: rename internal _flag to state, to save a qstr
- modlwip: add support for leaving multicast groups
- vfs_posix_file: remove unused MICROPY_VFS_POSIX_FILE
- modframebuf: optimise argument handling
- modframebuf: add fill argument to rect()
- modframebuf: add ellipse drawing method
- modframebuf: add polygon drawing methods
- modframebuf: improve poly-fill boundary pixels
- network_wiznet5k: use the configured DNS address if available
- machine_i2c: call MICROPY_PY_EVENT_HOOK during i2c.scan()
- modure: convert byte offsets to unicode indices when necessary
- modbluetooth: fix descriptor registration with empty tuple
- modbluetooth: replace def_handle with end_handle in char IRQ
- vfs: add finaliser to ilistdir to close directory handle
- vfs_posix_file: implement finaliser for files
- modbluetooth: change data_len type from size_t to uint16_t
- modbluetooth: do GATTC reassembly in protected uPy context
- modbluetooth: run BLE IRQ callback in protected NLR context
- extmod.mk: make extmod.mk handle GIT_SUBMODULES
- make extmod.mk self-contained
- utime_mphal: make ticks_add check for overflow of delta
- btstack: update BTstack bindings to work with latest BTstack
- mbedtls: add common configuration file, and use it in all ports
- mbedtls: enable MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE
- mbedtls: enable elliptic curve DH and DSA cryptography
- mbedtls: remove MBEDTLS_ECP_DP_CURVE25519_ENABLED config
- mbedtls: remove brainpool curves from config
- machine_timer: move stm32's implementation of machine.Timer here
- vfs_posix: include errno.h and unistd.h headers
- extmod.cmake: allow overriding the default MBEDTLS_CONFIG_FILE
- modlwip: use actual errno in exception for error in listen
- extmod.mk: set default mbedtls config file in extmod Makefile
- btstack: allow the BTstack config to be overridden by a board
- add and reorganise compilation guards and includes
- extmod.cmake: add MICROPY_PY_BTREE compiler definition
- moduplatform: remove _M_IX86 test for xtensa
- moduplatform: fix MSVC x86_64 check
- modframebuf: fix crash in FrameBuffer scrolling beyond extents
- uasyncio: fix syntax of generator functions
- modnetwork: use a type protocol to implement NIC functions
- modussl_mbedtls: fix support for ioctl(MP_STREAM_POLL)
- network_cyw43: fix handling of networks with open security
- axtls-include: add back needed header files for building axTLS
- utime_mphal: fix comment re delta range check in time_ticks_add
- modbtree: move system includes within MICROPY_PY_BTREE guard
- modnetwork: add network.hostname() and network.country()
- modnetwork: allow more extensive port-specific customisation
- network_cyw43: use CYW43_CHANNEL_NONE for default arg in connect
- vfs_posix: do not filter '..*' in ilistdir when filtering '..'
- network_ninaw10: check socket types when creating new sockets
- network_cyw43: fix setting hostname using config() method
- network_cyw43: add support to get STA RSSI using status() method
- network_ninaw10: add missing raw socket type to socket()
- btstack: switch to use hci_dump_init instead of hci_dump_open
- modbluetooth: merge gatts_notify/indicate implementation
- btstack: fix indicate/notify queuing
- btstack: include value handle in client read/write events
- btstack: fix MTU handling
- btstack: add support for CCCD to allow client subscriptions
- nimble: fix flags for descriptor registration
- modbluetooth: make all HCI transports trace in the same format
- btstack/modbluetooth_btstack: add default services

shared:
- runtime/tinyusb_helpers: add TinyUSB helper functions
- netutils/dhcpserver: match default DNS to server IP
- readline: use MP_REGISTER_ROOT_POINTER()
- runtime/pyexec: use MP_REGISTER_ROOT_POINTER()
- runtime/softtimer: move softtimer.[ch] to shared/runtime
- runtime/softtimer: remove obsolete #include statement
- runtime/sys_stdio_mphal: make func static and remove some TODOs
- runtime/gchelper_native: fix pointer cast on x86_64
- netutils: add "py/obj.h" header include
- tinyusb: create common TinyUSB code for reuse by ports
- tinyusb: further refactor static USB device implementation
- tinyusb: fix CDC bNumInterfaces value
- runtime: use mp_printf consistently, instead of printf
- runtime/gchelper: drop cpu directive from ARM asm helpers
- runtime/softtimer: use consistently the same clock source
- runtime/softtimer: fix ticks range when computing ticks diff
- tinyusb: allow max USB descriptor string to be configured
- runtime/pyexec: don't allow Ctrl+C to interrupt frozen boot code
- tinyusb: revert setting of CFG_TUD_CDC_EP_BUFSIZE to 256

drivers:
- hts221: add HTS221 humidity sensor driver
- lsm9ds1: add LSM9DS1 IMU driver
- lps22h: add LPS22HB/HH pressure sensor driver
- lps22h: use machine.idle for power saving
- ninaw10/nina_wifi_bsp: use MP_REGISTER_ROOT_POINTER()
- fix a few typos in comments
- cyw43: allow configuring the netif/mDNS hostname
- sdcard: add delay in init_card_v1 to make timeout work
- wiznet5k: remove old Wiznet driver
- cc3000: remove CC3000 WiFi driver files
- display: don't include tests by default
- remove drivers that are now in micropython-lib
- ninaw10: connect to WiFi asynchronously
- bus: detect QSPI transfer errors and pass up to spiflash driver
- bus: change QSPI read_cmd signature to return an error code
- ninaw10: implement machine.Pin external pin controls
- cyw43: use board-defined BLE UART secondary baudrate
- cyw43: use a different baudrate for BT firmware download
- ninaw10: fix machine_pin GPIO read
- cyw43: include CYW43 config file
- ninaw10: add missing external pins 34 and 39
- ninaw10: fix ESP32 input-only pins

mpy-cross:
- Makefile: respect existing CFLAGS and LDFLAGS
- remove .gitignore file
- include alloca.h for NetBSD
- mpy_cross: add Python wrapper for mpy-cross
- mpy_cross: fix default path to mpy-cross binary
- mpy_cross: add a way to query the mpy version
- mpy_cross: add list of architectures to `__all__`
- mpy_cross: add docstrings to public methods
- main: don't set a default native architecture
- main: add MSVC-compatible architecture checks
- force forward slashes in paths
- main: fix return type of mp_import_stat

lib:
- cyw43-driver: add new submodule for CYW43xx WiFi driver
- pico-sdk: update to version 1.4.0
- cyw43-driver: update cyw43-driver to fix ap_auth mode setting
- tinyusb: update to the most recent master
- cyw43-driver: update driver to latest version
- micropython-lib: add micropython-lib as a submodule
- lwip: update lwIP to v2.1.3, tag STABLE-2_1_3_RELEASE
- micropython-lib: update to latest version with manifest changes
- micropython-lib: update submodule to latest
- stm32lib: update library to get L1 v1.10.3, and some other fixes
- micropython-lib: update submodule to latest
- btstack: update to v1.5.3
- micropython-lib: update submodule to latest
- libm: use __asm__ instead of asm
- btstack: update to v1.5.4
- cyw43-driver: update driver to latest version
- re1.5: reduce code size when checking for named class char
- re1.5: add support for named classes in class sets
- micropython-lib: update submodule to latest
- cyw43-driver: update driver to latest version
- pico-sdk: update to version 1.5.0
- cyw43-driver: update driver to latest version v0.9.0
- micropython-lib: update submodule to latest
- stm32lib: update library to get H7 v1.11.0
- cyw43-driver: update driver to latest version v1.0.0
- micropython-lib: update submodule to latest

Support components
==================

docs:
- update to use new WLAN argument names for ssid/security/key
- library/pyb.Timer: document `brk` argument and its constants
- library: remove unnecessary "pyb." prefix on class names
- set LaTeX engine to XeLaTeX for PDF generation
- library/machine: add note on interrupts being critical to system
- library/uasyncio: consistently use "uasyncio" instead of "asyncio"
- library/bluetooth: add link to aioble
- library/neopixel: add note that neopixel is included in rp2 builds
- library/time: provide more info about which epoch is used
- library/pyb.Pin: fix out-of-context paragraphs, and AF_PP typo
- library/pyb.Pin: add Pin.ALT constant
- library/pyb.Timer: document how to use BKIN pin with example
- update links for Arm GCC toolchain
- library/rp2: fix pull_thresh docs to use pull instead of push
- esp32: fix string quoting consistency in SDCard mount example
- update CPython differences and improve the look of table layouts
- esp32: update UART quickref on input-only pins
- library/machine.UART: add notes about UART init and deinit
- library: fix nested rst styles not rendering
- library/micropython: fix spelling of compiler
- templates/topindex.html: update forum link
- library/machine.I2C: add a note about I2C pull-up resistors
- library/machine.UART: add docs for uart.flush() and uart.txdone()
- renesas-ra: add pin drive keyword argument description
- Makefile: enable parallel compilation for Sphinx
- templates/layout.html: indicate latest vs release docs
- samd: add documentation for the samd port
- library/machine: add machine.memX to docs with brief example
- samd/pinout: fix the pin numbering for the default assignments
- develop: fix mp_compile snippet to match latest code
- renesas-ra: correct the internal file system size of EK-RA6M2
- library/array: add docs for dunder methods
- library/pyb.CAN: update the recv example to take a 5-tuple
- library/uasyncio: describe restriction on ThreadSafeFlag
- library/framebuf: clarify docs for blit regarding palette
- library/struct: fix buffer argument description
- library/struct: embed format tables
- library/neopixel: update GitHub URL for neopixel.py link
- differences: update Python 3.9 status
- differences: add Python 3.10 page
- rp2: make LED have exactly 50% duty cycle in PIO 1Hz example
- library/rp2.StateMachine: expand put() documentation
- library/socket: use correct sockaddr variable name
- esp32/quickref: add docs for the LAN interface constructor
- library/machine.Timer: add freq argument to machine.Timer
- reference/constrained: add missing heap-dump symbols to mem_info()
- zephyr/quickref: fix zsensor module usage examples
- library/network: update docs for network.country, network.hostname
- update copyright year range to include 2023

examples:
- embedding: remove obsolete axtls build target
- usercmodule: add example of a native C class
- embedding: rework example to use ports/embed
- rp2: add comment that examples using IO25 don't work on Pico W
- bluetooth: fix check for _conn_handle being None
- usercmodule/cexample: use mp_obj_malloc()
- bluetooth/ble_temperature_central.py: remove service tuple

tests:
- extmod: add heap-lock test for stream writing
- basics: add tests for __name__ and __globals__ attrs on closures
- perf_bench: add some configurations for N=32, M=10
- add an explanation of run-perfbench.py
- fix run-perfbench parsing "no matching params" case
- micropython: add test for builtin execfile() function
- extmod/ussl_basic: make test run on axtls and mbedtls
- cpydiff: fix formatting of code snippet to use double quotes
- run-tests.py: provide better default MPYCROSS value for Windows
- extmod/ubinascii: add tests for bytes.hex etc
- update path to unix micropython executable
- unicode: add test for invalid utf-8 file contents
- renesas-ra: update pin test to support all boards
- extmod/uasyncio_heaplock.py: force SKIP on stackless
- frozen: move frozentest.mpy from ports/ to tests/
- run-multitests: extend usage information
- run-multitests: make paths more deterministic
- allow 'special' tests to output "SKIP" on a single line
- extmod: add test for sleep_ms value that overflows ticks
- run-perfbench: support --heapsize argument and pass to executable
- basics: add exp file for builtin_str_hex test
- run-tests.py: use host arch for mpy-cross for target=unix
- misc: add test for cexample module
- misc/cexample_module: test class presence
- misc/cexample_class: fix timing sensitivity
- extmod/framebuf_scroll: add tests for FrameBuffer scrolling
- unix/mod_os: add test for os module
- extmod/ure_namedclass: add tests for named classes in class sets
- float: skip new complex tests if complex unavailable
- extmod: get DecompIO test running on low-memory targets
- extmod: skip vfs tests if target doesn't have enough memory
- micropython: split viper_misc test into two files
- float: add domain checks for log and also -inf
- float: make output of math function tests more readable
- run-multitests.py: add ability to test instance over reboot
- multi_bluetooth: add bluetooth multi-test for deepsleep
- run-multitests.py: support outputting test metrics
- multi_bluetooth: use multitest.output_metric in BLE perf tests
- extmod/vfs_fat_ilistdir_del.py: use 512-byte erase block size
- multi_bluetooth: use time.sleep_ms instead of time.sleep
- multi_bluetooth/ble_mtu: split peripheral/central-initiated
- multi_bluetooth/ble_subscribe: use end_handle in desc discovery
- multi_bluetooth: add test for descriptors
- multi_bluetooth/ble_characteristic.py: add write-no-response
- multi_bluetooth: use multitest.broadcast instead of sleep

tools:
- metrics.py: add mimxrt and renesas-ra to list of available ports
- ci.sh: drop ppa requirement for code formatting CI
- pyboard.py: add verbose option to filesystem_command
- mpremote: don't be verbose when using cat command
- autobuild: add nrf port to autobuild scripts
- ci.sh: initialise submodules for more ports
- ci.sh: force mpy-cross build for samd and teensy
- update path to unix micropython executable
- mpremote: allow + terminator for fs commands
- pyboard.py: add "touch" filesystem command
- mpremote: add "edit" command
- ci.sh: split the stm32 builds for wiznet5k and cc3k
- mpremote: print a nicer error when a filesystem command fails
- pyboard.py: remove implicit fs_put if source starts with ./
- pyboard.py: add fs_cp function for direct device-to-device copy
- mpremote: print nicer errors for unsupported 'cp -r' arguments
- manifestfile.py: add library for working with manifests
- makemanifest.py: update to use mpy_cross module
- manifestfile.py: allow include of directory path
- manifestfile.py: allow require() to specify unix packages
- manifestfile.py: allow manifests to set metadata
- autobuild: use distinct directory for building stm32 variants
- makemanifest.py: force the repo version of the mpy_cross package
- pyboard.py: support Windows pathname separators
- manifestfile.py: add `author` kwarg to metadata()
- manifestfile.py: replace recursive glob with os.walk
- mpremote: simplify dispatch of commands
- mpremote: use argparse for command line parsing
- mpremote: add `mpremote mip install` to install packages
- pyboard.py: handle unsupported fs command
- add note about uncrustify versions
- add pre-commit support
- mpremote: fix argument handling for follow and add help strings
- mpremote: bump version to 0.4.0
- verifygitlog.py: ignore comment lines in commit messages
- verifygitlog.py: add additional help for subject line issues
- mpremote: handle FileNotFound exceptions in listdir
- mpremote: make RemoteFile objects iterable
- makemanifest.py: fix printing of mpy_cross.CrossCompileError
- gen-cpydiff.py: use os.path.join and os.path.isdir
- gendoc.py: remove unused script
- ci.sh: add ARDUINO_NANO_RP2040_CONNECT to rp2 CI build
- ci.sh: remove one build from zephyr CI to speed it up
- ci.sh: don't print python2 version
- mpremote: allow EDITOR environment variable to work on Windows
- mpremote: only auto connect to serial device with USB VID/PID
- autobuild: create .uf2 file for seeed_xiao_nrf52
- pyboard.py: fix Python 2 compatibility
- pyboard.py: add parse kwarg to eval
- pyboard.py: add fs_{listdir,readfile,writefile,stat}
- pyboard.py: set DTR on Windows to avoid ESPxx hard reset
- mpy-tool.py: initialize line_info_top
- ci.sh: install pkg-config for macos builds
- ci.sh: add unix, stm32 and rp2 ports to code size check
- mpremote: use hatch to build mpremote package
- pyboard.py: use '/' exclusively when dealing with paths
- pyboard.py: fix joining of path in filesystem_command
- pyboard.py: fix ESPxx boards hanging in bootloader after reset
- manifestfile.py: add support for publishing packages to PyPI
- mpremote: add ctrl-x as additonal mpremote disconnect shortcut

CI:
- ISSUE_TEMPLATE: make minor improvements to placeholder text
- ISSUE_TEMPLATE: replace forum with Discussions
- workflows: print test failures for webassembly workflow
- workflows: bump actions/checkout to v3
- add dependabot to update GitHub Actions
- workflows: bump codecov/codecov-action from 1 to 3
- workflows: bump actions/setup-python from 1 or 2 to 4
- workflows: run unix port workflow if mpy-cross changes
- workflows: use ubuntu-20.04 when python2 is required
- workflows: run mpy-format CI when tests and examples change
- workflows: comment on code size change instead of failing CI
- workflows: fix code size comment workflow for non-PR
- workflows: cancel when branch is updated
- workflows: update existing comments for code_size_comment
- workflows/code_size: print code size change
- workflows: add "shared/**" to list of paths that trigger CI
- workflows: add workflow to build mpremote wheel
- workflows: bump actions/setup-python from 1 to 4
- workflows: bump actions/checkout from 2 to 3
- workflows: bump actions/upload-artifact from 2 to 3

The ports
=========

all ports:
- adapt mimxrt, nrf and rp2 ports to work with latest TinyUSB
- fix a few typos in comments
- remove unused mp_type_{fileio/textio} macros in mpconfigport.h
- always include debug information in the ELF
- always append to GIT_SUBMODULES
- use micropython-lib version of drivers in manifests
- make generated pin.c handling more consistent across ports
- make all network-capable boards use bundle-networking
- make BOARD default from BOARD_DIR in Makefile's
- rename remaining "Micro Python" to "MicroPython"
- fix MCU tags in Arduino board.json files
- implement simple write polling for stdout

bare-arm port: no changes specific to this component/port

cc3200 port:
- mpconfigport: remove mp_const_user_interrupt
- use MP_REGISTER_ROOT_POINTER()
- fix various array-based compiler warnings
- mods/pybuart: implement uart.flush() and uart.txdone()
- remove unused NIC type customisation

embed port:
- add new "embed" port which builds a simple C package
- fix arguments to mp_raw_code_load_mem

esp8266 port:
- modnetwork: rename WLAN keyword args to ssid/security/key
- mpconfigport: switch to ROM feature level configuration
- mpconfigport: disable MICROPY_PY_UTIMEQ
- rename WLAN dhcp_hostname config to hostname
- boards: enable reverse-special-methods on GENERIC board
- use MP_REGISTER_ROOT_POINTER()
- modnetwork: add support for WLAN.config(protocol=XX) option
- README: update build instructions to match ci.sh
- machine_uart: implement uart.flush() and uart.txdone()
- modmachine: move dht_readinto() to the machine module
- machine_pwm: enable real open drain output on pin driven by PWM
- machine_pin: disable open drain when pin becomes input/output
- modnetwork: add ability to set tx power for WLAN interface
- README: remove notice about port being "experimental"
- use extmod/modnetwork.c instead of port-specific version

esp32 port:
- network_wlan: rename WLAN keyword args to ssid/security/key
- machine_uart: implement the functionality of timeout_char arg
- boards: increase 512 bytes limit on ULP programs to 2040
- modesp32: add wake_on_ulp() so ULP can wake CPU from deepsleep
- network_wlan: don't raise exception when scan returns no results
- rename WLAN dhcp_hostname config to hostname
- modmachine: fix machine.freq to allow maximum 160MHz on ESP32-C3
- use MP_REGISTER_ROOT_POINTER()
- mpconfigport: enable BLE synchronous events and pairing/bonding
- Makefile: force micropython-lib as a required submodule
- network_wlan: use esp_wifi_set/get_channel to config wifi channel
- network_wlan: add support to set/get the wifi protocol
- modnetwork: add network.MODE_LR constant
- machine_uart: change sendbreak time to be at least 15 bit times
- machine_timer: support all init arguments in Timer constructor
- boards: merge manifest_release modules into standard manifest
- machine_sdcard: free SPI bus when deiniting SD card
- machine_uart: implement uart.flush() and uart.txdone()
- mphalport: fix calculation of large sleep by using 64-bit arith
- Makefile: add link to build troubleshooting on failure
- modsocket: use mp_obj_is_integer to test port type
- machine_pwm: don't use LEDC_USE_REF_TICK on ESP32-C3 variants
- machine_i2s: add I2S finaliser which calls deinit()
- machine_hw_spi: use auto DMA channel on S2, S3, C3 chips
- rename machine I2C and SPI types consistently across ports
- machine_i2c: fix clocks and timeouts for ESP32-C3, ESP32-S3
- machine_pin: fix size of machine_pin_irq_handler array
- machine_pwm: verify PWM is active when config methods are called
- add 32MiB partition table templates
- usb: add a timeout to usb_tx_strn()
- modmachine: move dht_readinto() to the machine module
- boards/GENERIC_S3_SPIRAM: enable BLE support
- boards/GENERIC_S3_SPIRAM: enable BLE
- machine_timer: fix ESP32C3 timer period doubling
- machine_touchpad: fix TouchPad for ESP32S2, ESP32S3
- main: don't call usocket_events_deinit if unavailable
- usb: cleanup connection detection
- boards/GENERIC_S3_SPIRAM_OCT: add ESP32S3 board with Octal SPIRAM
- network_lan: add support for LAN8710 PHY
- network_lan: support configuration of ETH ref_clk pin
- network_lan: add support for SPI-based ethernet chips
- network_lan: fix setting MAC address of ethernet devices
- network_lan: fix compilation on IDF lower than v4.4
- machine_sdcard: change dma_channel to SPI_DMA_CH_AUTO for ESP32S3
- boards: add board definition for Olimex ESP32 PoE boards
- boards/GENERIC_UNICORE: add board definition for unicore chips
- network_lan: add support for Ethernet PHY KSZ8081
- add a small delay before leaving wlan.active()
- boards/OLIMEX_ESP32_POE: remove id from and update board.json
- Makefile: allow specifying BOARD_DIR on make command line
- use extmod/modnetwork.c instead of port-specific version
- machine_pin: use const for size of machine_pin_irq_handler array
- esp32_rmt: fix looping behaviour for RMT on ESP32-S3

mimxrt port:
- Makefile: refactor Makefile and divide it into sections
- Makefile: modify handling of SDRAM option
- Makefile: modify handling of SDCARD option
- Makefile: rework board flash type handling
- Makefile: rework floating point config
- Makefile: fix some minor formatting inconsistencies
- boards: remove conditional assignment of flash type/size
- use MP_REGISTER_ROOT_POINTER()
- machine_uart: implement uart.flush() and uart.txdone()
- machine_uart: drop a few commented lines about TX ring buffer
- format the firmware image to match the new teensy loader
- machine_spi: allow a setting of -1 for cs in the constructor
- machine_uart: set the UART ioctl write poll flag properly
- machine_uart: fix a bug in UART.write()
- Makefile: split up SRC_C variables
- machine_pin: add the Pin.toggle() method
- fix CPU freeze when calling __WFE() in MICROPY_EVENT_POLL_HOOK
- machine_timer: use soft-timer implementation for machine.Timer
- machine_timer: use extmod version of machine.Timer
- mphalport: add a timeout to mp_hal_stdout_tx_strn()
- modmachine: move dht_readinto() to the machine module
- add support for MIMXRT1176 MCUs, and MIMXRT1170_EVK board
- README: add build and flashing instructions
- usb: change macro name MICROPY_HW_USB_STR_MANUF
- network: rename the argument clock_mode to ref_clk_mode
- Makefile: set MPY_CROSS_FLAGS
- mpconfigport: remove config options that are set by default
- machine_rtc: set the microsecond value to 0
- sdcard: fix an error when writing large blocks
- sdcard: remove obsolete code already excluded by preprocessor
- set MICROPY_GC_STACK_ENTRY_TYPE to uint32_t for large RAM
- Makefile: move the FROZEN_MANIFEST setting after board config
- enable ROM text compression
- pendsv: add MICROPY_BOARD_PENDSV_ENTRIES for board customisation
- pendsv: clean up PendSV code
- Makefile: fix internal flash configuration and build
- boards/MIMXRT1064_EVK: fix board config to use internal flash
- mpconfigport: allow configuring different network interfaces
- modmachine: implement machine.bootloader()
- fix the build for boards without ROM API

minimal port:
- Makefile: avoid terminal reset, use BUILD variable
- Makefile: set linker to $(CC)
- increase heap size for Linux builds

nrf port:
- main: add startup and early-init board hook macros
- modmachine: add machine.bootloader() and make it customisable
- enable optional support for Arduino 1200bps touch
- Makefile: drop unused MPY_CROSS and MPY_TOOL variables
- boards/arduino_nano_33_ble: add Arduino Nano 33 BLE sense board
- modmachine: add machine.idle() function
- mpconfigport: remove obsolete module declarations
- drivers/bluetooth: handle PHY_UPDATE messages, used in Bluetooth 5
- drivers/usb: probe for interrupt char in USB CDC task
- drivers/usb: add a tud_cdc_rx_cb() callback to check interrupt char
- mpconfigport: call tud_task() in MICROPY_EVENT_POLL_HOOK
- drivers/usb: fix reading of a single USB CDC character
- use MP_REGISTER_ROOT_POINTER()
- boards/arduino_nano_33_ble_sense: update deploy instructions
- main: call usb_cdc_init() before executing boot.py and main.py
- modules/ubluepy: use mp_obj_str_get_data to extract str data
- don't enable debug info by default if LTO is on
- modules/machine/uart: implement uart.flush() and uart.txdone()
- Makefile: split up SRC_C variables
- rename machine I2C, PWM, SPI, UART types consistently across ports
- rename MICROPY_PY_MACHINE_TIMER to MICROPY_PY_MACHINE_TIMER_NRF
- boards/seeed_xiao_nrf52: add defn for Seeed XIAO NRF52840 Sense
- mpconfigport: enable seeding of the PRNG by the hardware RNG
- Makefile: add support for BOSSAC flasher
- boards/arduino_nano_33_ble_sense: add support for REV-2 chipset
- modules/machine/pwm: add paramter checks and error messages
- modules/machine/pwm: use extmod/machine_pwm.c for PWM module
- modules/machine/soft_pwm: add PWM for nrf51x boards using soft PWM
- modules/machine/pwm: support using all 4 channels of a PWM module
- modules/machine/uart: add timeout keyword options and "any" method
- nrfx_config: use the UARTE definitions and drivers for the NRF52xx
- modules/machine: use a dedicated function for machine.idle()
- modules/machine: support the freq=n argument for machine.I2C
- modules/machine/pwm: fix resource conflict, and change id to device
- nrfx_config: use UARTE for nrf52xxx devices
- modules/machine/uart: prevent UART lock-up after a receive error

pic16bit port:
- pic16bit_mphal: use MP_REGISTER_ROOT_POINTER()

powerpc port: no changes specific to this component/port

qemu-arm port: no changes specific to this component/port

renesas-ra port:
- modmachine: allow boards to provide custom bootloader code
- machine_i2c: remove unnecessary start/stop dummy functions
- mpconfigport: drop pyb_hid_report_desc root pointer
- use MP_REGISTER_ROOT_POINTER()
- softtimer: switch to use softtimer code from shared/runtime
- machine_pin: support drive keyword and fix GPIO setting
- rename machine SPI type consistently across ports
- machine_timer: use extmod version of machine.Timer
- boards: update linker script to detect code flash overflow
- disable debugging option for RA4 to reduce code size
- change file system size to 64KB for RA6M1
- add the UART methods uart.txdone() and uart.flush()

rp2 port:
- modmachine: allow boards to provide custom bootloader code
- boards/ARDUINO_NANO_RP2040_CONNECT: enable Arduino 1200bps touch
- modmachine: implement lightsleep() with optional sleep period
- mpthreadport: ensure core1 doesn't hold gc lock in deinit
- mbedtls: enable some more mbedtls options
- lwip_inc: enable lwIP status callback
- rp2_flash: add asserts for size of flash filesystem partition
- mpnetworkport: convert network task scheduling to use PendSV IRQ
- integrate CYW43xx WiFi driver
- boards/PICO_W: add new Pico W board, an RP2040 with WiFi
- boards/GARATRONIC_PYBSTICK26_RP2040: change pico-sdk board name
- main: set default AP auth mode to WPA2_AES_PSK
- mpconfigport: factor core event handling to EVENT_POLL_HOOK_FAST
- Makefile: regenerate cmake if generated Makefile missing
- CMakeLists: give error if required submodules are missing
- CMakeLists: don't override cyw43-driver unless necessary
- boards/ARDUINO_NANO_RP2040_CONNECT: add urequests module
- run USB stack task exclusively from core 0
- make atomic sections suspend the other core (if active)
- mpconfigport: make networking options consistent across boards
- mphalport: fix missing storage_read_blocks symbol in debug build
- CMakeLists: use armv6m mpy-cross arch for rp2
- use MP_REGISTER_ROOT_POINTER()
- mpbthciport: remove mp_bthci_uart from set of root pointers
- cyw43_configport: set CYW43_EVENT_POLL_HOOK value
- cyw43_configport: set CYW43_WIFI_NVRAM_INCLUDE_FILE value
- rp2_pio: fix StateMachine.restart when PIO program is shared
- cyw43_configport: add event hook into cyw43_delay_ms
- Makefile: always use cmake to discover submodules
- mbedtls: enable certificate validity time validation
- machine_spi: add mp_hal_get_spi_obj helper function
- boards/W5500_EVB_PICO: add new board definition for W5500_EVB_PICO
- mark gc_heap NOLOAD for faster boot
- correctly determine path to arm-none-eabi-size
- machine_wdt: check for the maximum timeout value of watchdog
- machine_uart: implement uart.flush() and uart.txdone()
- mbedtls: fix missing time.h include
- rp2_flash: add start/len support to rp2.Flash() constructor
- boards: set PICO_BOARD correctly for each board
- machine_spi: use pico-sdk's default pins for SPI
- machine_i2c: use pico-sdk's default pins for I2C
- boards: remove all I2C,SPI pin defs that already match pico-sdk
- Makefile: add link to build troubleshooting on failure
- Makefile: add support for BOARD_VARIANTS
- boards/WEACTSTUDIO: add WEACTSTUDIO with multiple variants
- fatfs_port: fix the modification date of files
- rename machine I2C type consistently across ports
- mphalport: add a timeout to mp_hal_stdout_tx_strn()
- cyw43_configport: make sure only core0 executes a __WFI()
- modmachine: move dht_readinto() to the machine module
- allow enabling USB device without enabling USB-CDC
- boards/ARDUINO_NANO_RP2040: add more modules and enable MD5 hash
- fix lightsleep to work with interrupts and cyw43 driver
- machine_pwm: use more accurate formulas for freq and duty_u16
- machine_pwm: fix overflows with freq > 268 MHz
- mphalport: change order of pin operations to prevent glitches
- rp2_flash: call MICROPY_EVENT_POLL_HOOK_FAST after reading flash
- machine_pin: refactor the machine.Pin class for external GPIO
- machine_pin: add support for named pins and alternate functions
- boards: add pin CSV files to board definitions
- fix crash in a pin.irq handler
- main: use mp_printf in nlr_jump_fail
- machine_pin: fix configuring OPEN_DRAIN with initial value
- boards/NULLBITS_BIT_C_PRO: add Bit-C PRO board
- rp2_pio: track use of PIO resources and free them on soft reset
- boards/ARDUINO_NANO_RP2040_CONNECT: use default aioble
- mpconfigport: enable os.dupterm and hashlib.sha1 on all boards
- cyw43_configport: specify the chipset firmware include file
- Makefile: allow specifying BOARD_DIR on make command line
- pendsv: add MICROPY_BOARD_PENDSV_ENTRIES for board customisation
- boards/ARDUINO_NANO_RP2040_CONNECT: include "time" in manifest
- boards/ARDUINO_NANO_RP2040_CONNECT: add more external pins
- boards/ARDUINO_NANO_RP2040_CONNECT: include "senml" in manifest
- modrp2: support reading the BOOTSEL button on the Pico board
- modrp2: disable other core, shorten delay to 8us in bootsel_button
- allocate GC heap from unused RAM
- allow disabling USB via MICROPY_HW_ENABLE_USBDEV config
- main: keep UART REPL with DEBUG=1 and MICROPY_HW_ENABLE_UART_REPL=1
- machine_uart: fix setting of UART LCR parameters
- machine_i2c: add timeout parameter for machine.I2C()
- memmap_mp.ld: allow a board to reserve memory for the C heap

samd port:
- mpconfigport: enable MICROPY_ENABLE_FINALISER when VFS is used
- remove the existing provisional support for REPL on UART
- boards: replace pins.c and pins.h by pins.csv
- boards: move mcu-specific settings into a mpconfig_samdXX.h file
- Makefile: alphabetically sort the source code files in Makefile
- boards: add ADAFRUIT_FEATHER_M4_EXPRESS and _ITSYBITSY_M0_EXPRESS
- clock_config: set up the clock configuration
- modmachine: allow changing the CPU freq with machine.freq(f)
- mphalport: add pin open-drain funcs, and improve delay and ticks
- samd_isr: extend systick_ms to 64 bit
- machine_pin: add OPEN_DRAIN mode for pins
- machine_pin: allow specifying a pin or LED by its name as a string
- modmachine: enable SoftSPI and SoftI2C
- boards: create pin_af_table.c from pin_af_table_SAMDxx.csv files
- pin_af: add the pin af table and its helper functions
- machine_adc: add the machine.ADC class
- machine_pwm: add the machine.PWM class
- samd_isr: rework the interrupt tables
- machine_pin: add pin.irq() to the machine.Pin class
- modmachine: add disable_irq(), enable_irq() and idle() to machine
- machine_uart: add the machine.UART class
- machine_spi: add the machine.SPI class
- machine_i2c: add the machine.I2C class
- moduos: add uos.dupterm()
- moduos: add uos.urandom() for SAMD51
- main: use the common execution mode of boot.py and main.py
- mpconfigport: enable a few more MicroPython features
- samd_isr: change the way a Sercom ISR is registered and called
- machine_timer: add machine.Timer based on the shared soft-timer
- machine_wdt: add the machine.WDT class
- modsamd: add pininfo() function to the samd module
- machine_led: optimise size of the machine.LED class
- machine_dac: add the machine.DAC class
- modmachine: add machine.time_pulse_us
- mcu: factor out MCU policy for SAMD21 and SAMD51
- mphalport: add a mp_hal_ticks_ms_64() function
- modutime: enable time.time() based on systick_ms()
- machine_uart: support buffered TX for UART
- boards: add missing/lost board config and pin definitions
- mphalport: use CYCCNT for SAMD51's mp_hal_ticks_cpu()
- machine_bitstream: add the machine.bitstream() function
- mpconfigport: restructure to use ROM feature levels
- clock_config: split clock_config.c to separate SAMD21/SAMD51 files
- clock_config: add HW_DFLL_USB_SYNC and HW_MCU_OSC32KULP extensions
- pin_af: simplify the pin-af-table handling
- samd_flash: remove obsolete printf's and return values instead
- Makefile: fix a dependency problem with "make -j"
- mphalport: fix USB endpoint handling ignoring Ctrl-C
- change the symbol names for the peripheral clocks
- mcu: add floating point suport for SAMD21 devices
- mcu: enable the math module on SAMD51
- boards: move the flash filesystem definitions to the linker files
- boards: use the same linker file for all SAMD51x19 variants
- main: initialize readline on start up
- mcu: use lf2s for SAMD51 and lfs1 for SAMD21
- machine_pin: change the printing of Pin and LED objects
- Makefile: split up SRC_C variables
- rename machine I2C type consistently across ports
- clock_config: extend the range of machine.freq()
- clock_config: support changing machine.freq() for SAMD21
- modmachine: add machine.reset_cause()
- boards/SPARKFUN_SAMD51_THING_PLUS: add board files for Thing Plus
- modmachine: add machine.dht_readinto and enable on SAMD51
- mcu/samd51: enable onewire support for SAMD51
- mcu/samd51: enable FAT support for SAMD51
- modmachine: implement machine.lightsleep()
- modmachine: get the bootloader magic address from the lib
- clock_config: document the #defines use in init_clocks()
- machine_uart: implement uart.txdone() and uart.flush()
- mcu: make some settings in mpconfigmcu.h conditional
- machine_rtc: add the machine.RTC class
- clock_config: extend the SAMD51 us-counter to 60 bit
- boards/SEEED_WIO_TERMINAL: declare more pins for SEEED WIO board
- machine_pin: change the pin handling and naming/numbering
- make ADC, DAC, PWM, SPI objects consistent in how they print out
- modmachine: replace the LED class by the Signal class
- boards: rework the pins.csv files
- machine_pwm: serialize fast update of PWM settings
- machine_uart: use a finaliser to tidy up UART on soft reset
- machine_spi: implement spi.deinit() and simplify sercom_deinit_all
- machine_spi: register SerCom objects as root pointers
- modmachine: add machine.softreset()
- machine_timer: use extmod version of machine.Timer
- mcu/samd51: use an additional manifest.py for SAMD51 boards
- README: update README to reflect recent changes to the port
- boards/SEEED_WIO_TERMINAL: enable using the 32kHz crystal
- mphalport: add a timeout to mp_hal_stdout_tx_strn()
- move MCU-specific CFLAGS to mpconfigmcu.mk
- Makefile: set MPY_CROSS_FLAGS
- mpconfigport: support MICROPY_HW_SOFTSPI_MIN_DELAY
- mpconfigport: use __WFE() in MICROPY_EVENT_POLL_HOOK
- avoid under-/overflow in I2C and SPI baudrate calculations
- machine_uart: fix IRQ flag setting and clearing
- machine_uart: simplify machine_uart_any() and machine_uart_read()
- machine_uart: check the UART TX pin assignment
- machine_uart: fix uart.deinit() and save some RAM
- add a vref=num option to the ADC and DAC constructor
- support entering bootloader via USB CDC 1200bps touch
- boards/SEEED_XIAO: rename to SEEED_XIAO_SAMD21
- add Pin.board and Pin.cpu classes to Pin
- boards: clean up comments and some pins in pins.csv files
- mcu: rework the comments in clock_config.c
- mcu: use the FDPLL96M clock for the SAMD21 CPU
- mcu: implement a hardware seed for the SAMD21 random module
- mcu: set the SAMD21 us-counter to 2 MHz for better resolution
- moduos: add uos.urandom() using the phase-jitter rng
- pendsv: add MICROPY_BOARD_PENDSV_ENTRIES for board customisation
- always provide the machine.RTC class

stm32 port:
- modmachine: allow boards to provide custom bootloader code
- modmachine: factor out mboot enter code to a function
- boards/stm32f091xc.ld: allocate space for a small filesystem
- boards/NUCLEO_F091RC: enable LFS1 filesystem
- Makefile: set CSUPEROPT to -Os for F0 and G0 MCUs to save space
- usbd_cdc_interface: add support for Arduino 1200bps touch
- usb: expose USB HID device instance via usbd_hid_get()
- use a separate symbol name for the bootloader state pointer
- Makefile: enable link-time-optimisation via LTO=1 make option
- boards: enable LTO by default on boards with smaller flash size
- Makefile: fix setting of define that enables WIZNET5K driver
- mboot: remove redundant code in mboot_state_change function
- boardctrl: allow boards to override fatal-error handler
- sdram: include boardctrl.h for fatal-error handler
- use MP_REGISTER_ROOT_POINTER()
- Makefile: workaround LTO linker order bug in binutils <2.35
- softtimer: switch to use softtimer code from shared/runtime
- boards/LEGO_HUB_NO6: fix typo in README
- boards/LEGO_HUB_NO6: use named pins
- boards/LEGO_HUB_NO6/appupdate: detect filesystem size at runtime
- boards/LEGO_HUB_NO6/spiflash: pick command type at runtime
- boards/LEGO_HUB_NO6/cc2564: make timer configurable
- boards/LEGO_HUB_NO7: add LEGO Hub No. 7 board definition
- boards/NUCLEO_WB55: add error handling to firmware update scripts
- don't enable debug info by default if LTO is on
- switch Wiznet to use lib/wiznet5k and extmod/network_wiznet5k
- add definitions required for lwIP version of Wiznet NIC
- mphalport: add mp_hal_get_spi_obj() helper function
- sdram: enable MPU for unaligned access on H7 MCUs
- boards: increase mboot region to 32k for WB55 boards
- move board variant config to mpconfigboard.mk
- boardctrl: use HAL_Delay instead of mp_hal_delay_ms
- remove support for CC3000 WiFi driver
- machine_uart: implement uart.flush() and uart.txdone()
- boards/LEGO_HUB_NO6: update manifest to new format
- boards: only freeze LCD160CR driver in PYB board firmware
- adc: make ADCAll.read_channel reject invalid channels
- pyb_i2c: fix pyb.I2C to work with dma=True on F4 MCUs
- timer: fix use of timer channel callback() method on L4 MCUs
- boards: add alternate function list for STM32F446RE
- boards/PYB: fix handling of BOARD_VARIANT selection
- make-stmconst.py: support TypeDef's with a single char prefix
- add support for STM32L1 MCUs
- boards/NUCLEO_L152RE: add NUCLEO-L152RE board support
- rename machine I2C and SPI types consistently across ports
- boards/ARDUINO_PORTENTA_H7: revert to single-precision float
- mbedtls: enable mbedtls certificate time validation
- Makefile: allow overriding the default MBEDTLS_CONFIG_FILE
- boards/ARDUINO_PORTENTA_H7: add custom mbedtls config
- modmachine: move dht_readinto() to the machine module
- spi: downgrade SPIHandle definitions to static
- boards/ARDUINO_PORTENTA_H7: add more modules, I2C1 and SE pin
- usbd_desc: support USB strings on CDC interface descriptors
- Makefile: set MPY_CROSS_FLAGS based on MCU type
- pyb_i2c: fix failing pyb.I2C(dma=True) after receiving 1 byte
- i2c: fix I2C frequency calc so it doesn't exceed requested rate
- adc: fix reading internal ADC channels on L4 MCUs
- adc: fix ADCAll.read_core_temp() on L4 MCUs
- i2c: add hardware I2C implementation for STM32L1
- i2c: add hardware I2C implementation for STM32L4
- mboot: make all mboot sectors erase/write protected
- boards: add missing LPUART macros for H7 HAL
- boards/NUCLEO_F429ZI: enable I2C1 and I2C2 with default pins
- powerctrl: improve standby mode entry code for H7 MCUs
- boards/NUCLEO_F756ZG: add board definition for NUCLEO-F756ZG
- powerctrl: fix build on STM32G0xx and STM32H7Bx MCUs
- boards: consolidate linker snippets to reduce duplication
- Makefile: leave DFU mode after download when using dfu-util
- boards/NUCLEO_H743ZI2: refer to NUCLEO_H743ZI for frozen manifest
- boards/STM32F769DISC: fix building with USE_QSPI_XIP=1
- boards/ARDUINO_PORTENTA_H7: fix macro value check for QSPI
- boards/ARDUINO_PORTENTA_H7: use default aioble
- Makefile: clean up nested if-else to chained if-else-if
- update to use the open-source lib version of cyw43-driver
- boards: update linker scripts now that big_const is gone
- add a default implementation of pyb.country
- cyw43_configport: fix build for boards without an RF switch
- boards/PYBD_SF2: set CYW43 Bluetooth fimrware download baudrate
- cyw43_configport: allow boards to override default resource files
- boards/ARDUINO_PORTENTA_H7: update board config files
- Makefile: include HAL HSEM driver on H747 MCUs
- boards/ARDUINO_NICLA_VISION: add support for Arduino Nicla Vision
- boards/ARDUINO_GIGA: add support for Arduino Giga H7 board
- cyw43_configport: add cyw43_sdio_enable_high_speed_4bit function
- powerctrl: add sleep RCC semaphore management for WB55 MCUs
- powerctrl: disable WB55 BLE before entering deepsleep
- powerctrlboot: provide custom SystemInit for WB55
- powerctrl: don't compile WB helpers on WL MCUs
- boards: include "senml" in manifest for ARDUINO boards
- remove commented-out printf's and debugging code
- main: use mp_printf instead of printf for MPY start-up messages
- i2c: return error code and raise exception if I2C init fails
- spi: return error code and raise exception if SPI init fails
- modmachine: make machine.info print using mp_printf
- extint: make ExtInt.regs print using mp_printf
- pin: make pin_find debug output use mp_printf
- pybthread: make pyb_thread_dump take a printer as its argument
- boards/NUCLEO_H743ZI2: fix MCU tag in board.json file
- mphalport: update HAL version to 1.11.0 to match stm32lib
- add support for STM32H723 MCUs
- boards: add ld and af.csv for H723
- boards/NUCLEO_H723ZG: add new H723 board
- add support for USB on G0 MCUs
- mboot: add support for G0 MCUs
- boards/NUCLEO_G0B1RE: add config for USB and mboot
- boards/ARDUINO_NICLA_VISION: fix incorrect bootloader PID
- flash: fix get_bank function for STM32H750
- cyw43_configport: provide cyw43_hal_pin_config_irq_falling func

teensy port:
- mpconfigport: drop unused root pointers
- teensy_hal: use MP_REGISTER_ROOT_POINTER()

unix port:
- variants: move setting of MICROPY_PY_USELECT to port config file
- variants: enable remaining options on dev,coverage from ROM extra
- variants/coverage: change config to use ROM level everything
- variants/dev: allow all config options to be overridden
- moduos: include errno.h
- main: restore tty settings on nlr_jump_fail()
- alloc: use MP_REGISTER_ROOT_POINTER() for mmap_region_head
- mpconfigport: make MICROPY_EVENT_POLL_HOOK call usleep directly
- mbedtls: add custom config for mbedtls
- mpconfigport: switch ussl from axtls to mbedtls
- Makefile: only include axtls in GIT_SUBMODULES list when enabled
- Makefile: only checkout libffi submodule when used
- mpconfigport: allow overriding MICROPY_EVENT_POLL_HOOK
- enable MICROPY_GC_SPLIT_HEAP on coverage build
- unix_mphal: allow overriding hal time functions
- variants: remove variant suffix from executable filename
- modjni: add missing const qualifier
- remove .gitignore file
- modusocket: support proto and flags arguments to getaddrinfo
- include alloca.h for NetBSD
- mpconfigport: enable MICROPY_ENABLE_FINALISER when VFS is used
- variants: remove freedos and fast variants
- refactor mpconfigport.h and mpconfigvariant.h
- refactor mpconfigvariant.mk
- variants/coverage: add test for manifest freeze_mpy()
- enable sys.executable
- Makefile: don't use _MOD variable names
- modffi: move header includes inside MICROPY_PY_FFI guard
- variants: change mip package to mip-cmdline
- coverage: add extra GC coverage test for ATB gap byte
- moduos: implement 2-arg version of os.getenv()
- Makefile: disable building the shared library of libffi
- main: free pathbuf when there's an error opening a file

webassembly port:
- Makefile: remove obsolete disable of array-bounds warning
- rename this port from 'javascript' to 'webassembly'
- mpconfigport: use MICROPY_CONFIG_ROM_LEVEL_EXTRA_FEATURES
- add support for VFS and enable VFS_POSIX
- use Date's now() instead of getTime()
- change "stack" argument to "heapsize"
- support piping in a program on stdin
- dispatch micropython-print via document not mp_js_stdout
- README: update README to describe new stdout behaviour
- Makefile: change compiler optimisation from O3 to Os
- library: make use of CustomEvent detail property
- library: extract and send data to print as UInt8Array

windows port:
- provide a definition for MP_ALWAYSINLINE
- msvc: support compressed ROM text for error messages
- Makefile: update test dependency on $(PROG)
- make project file read-only for IDE
- .gitignore: simplify by removing build artefacts
- msvc: remove variant suffix from executable filename
- msvc: make mpy-cross independent of micropython variant
- msvc: fix qstr generation dependency
- msvc: fix module freezing

zephyr port:
- update include paths to use the zephyr namespace
- upgrade to Zephyr v3.1.0
- use MP_REGISTER_ROOT_POINTER()
- machine_uart: use mp_obj_str_get_str to get device name
- boards: add config for bbc_microbit_v2
- mpconfigport: enable MICROPY_ENABLE_FINALISER when VFS is used
- rename machine I2C and SPI types consistently across ports

Bug fix for esp32 SoftI2C

This is a bug fix release.  The changes are:

- extmod/machine_i2c: only use WRITE1 option if transfer supports it

  This fixes the machine.SoftI2C.readfrom_mem() method on esp32, so it
  writes the address to read from.

New mpy 6 file format with improved bytecode, addition of renesas-ra port

In this release of MicroPython the .mpy file format has been significantly
reworked and bumped to version 6.  The new format now contains data and
bytecode organised to be mostly static and ready to run in-place.  To
achieve this, qstr references from bytecode (and native machine code) now
go through a lookup table, to convert from local qstr number in the module
to global qstr number in the runtime that the module executes within.  This
means bytecode (and most native code) does not need rewriting when it is
imported.  Along with this change, the jump opcodes have been optimised to
emit 1-byte jump offsets when possible, which gives a good reduction in
bytecode size, saving RAM and reducing the size of .mpy files.

The change to the bytecode means that code constants (like long strings,
bytes objects and floats) are now shared and de-duplicated across the whole
module, rather than each code object having a separate constant table.  The
parser can also now turn a tuple of constants into a constant object, so
the tuple doesn't need to be built at runtime each time it is used.
Furthermore, any constant object can now be used in "X = const(obj)"
statements.

With these bytecode changes, .mpy files see around a 10% reduction in size
and frozen .mpy code sees about a 5% size reduction.  Heap memory use after
import is also down by around 5% (more savings are seen if the code uses
lots of constants).  Due to the qstr indirection performance of the VM is
slightly reduced on some benchmarks by a few percent, but the benefits of
smaller code and reduced RAM usage are deemed to outweigh this.  See commit
f2040bfc7ee033e48acef9f289790f3b4e6b74e5 for more details.

In the runtime, support has been added for multiple *args and **args in a
function call, following PEP 448.  Built-in modules can now have (optional)
mutable attributes, and this is used to implement sys.ps1/sys.ps2 which
allow the user to customise the REPL prompt.  This can be useful, for
example, to configure a different REPL for different boards so they can be
easily distinguished.  The sys module has also had the MicroPython git
version and build date appended to sys.version, sys.implementation._machine
has been added, and sys.implementation.mpy renamed to
sys.implementation._mpy.  The sys module can now be used to fully identify
the MicroPython version and target it is running on (and the platform
module provides additional information when it's available).

The MP_REGISTER_MODULE macro is now used to register all built-in C modules
and the third argument to this macro has been removed.  Any user-C-modules
will need to be updated.  Also support for MICROPY_PORT_BUILTIN_MODULES is
removed because this is no longer needed, and should be replaced by usage
of MP_REGISTER_MODULE (see commit 0a92469c10542d57ef0ea6b6cf2ed0cae9491dbe
for example).

The MP_REGISTER_MODULE macro is now used to register all built-in C modules
and the third argument to this macro has been removed.  Also support for
MICROPY_PORT_BUILTIN_MODULES is removed because this is no longer needed.

mpy-cross now supports the -march=armv6m option, which can be used with the
rp2 port.  The -mno-unicode has been removed.

The littlefs2 library has been updated to v2.5.0 which includes some
performance improvements and minor fixes.

At the REPL, a tab will now insert an indent when it follows whitespace,
and auto-indent is automatically disabled if a space or tab follows an
auto-indent.  This means that Python code can be pasted into the standard
REPL without messing up the indentation.

mpremote is now at version 0.3.0, with a progress indicator shown when
copying large files, and recursive copy fixed on Windows.  It also has the
following commands added: --help, --version, version, resume, soft-reset,
umount.

The esp32 port has a new machine.ADCBlock class and updated ADC class.
Fixes have been made to ADC2 channel mapping, low PWM frequencies,
UART initialisation of unspecified parameters, and RMT channel on S2/S3/C3
variants.  The Pin.PULL_HOLD constant has been replaced by a "hold" keyword
argument to the Pic constructor, and it's now possible to configure pin
drive strength.  I2C write-then-read transfers have been optimised to be
faster.  WLAN.config() now supports setting/getting the txpower.  New
boards include LOLIN C3 MINI ESP32-C3, LilyGO LoRa32, and UM ESP32-S3 based
boards.

The mimxrt port has updated the nxp_driver to v2.10 and fixed USB CDC RX
handling to not block.  Pin drive constants have been renamed to DRIVE_x to
match other ports, and the machine.I2S class has been added.  New boards
include Olimex RT1010 and MIMXRT1015_EVK.

The nrf port now includes uasyncio in the default board manifest, and
additional features have been enabled on nrf52840 and nrf9160 boards to
match the features on stm32, rp2 and esp32.  This includes enabling the
json, re, zlib and framebuf modules.

There is a new renesas-ra port which targets Renesas RA4M1, RA4W1, RA6M1
and RA6M2 MCUs, with board definitions for evaluation kits for these MCUs,
along with RA4M1 clicker.  This port currently supports Pin, ADC, SoftI2C,
I2C, SoftSPI, SPI, UART, Timer and RTC classes in the machine module, along
with the VFS and an internal flash filesystem.

The rp2 port now has optional USB MSC support, and optional dupterm
support.  The machine.UART class has init and deinit methods added, and
the ucryptolib module is now available.  The lwIP network stack has been
integrated, along with mbedtls for the ssl module, and these can be used
with the new Wiznet driver to provide Ethernet support.  The Wiznet
W5100S-EVB-Pico board has been added which makes use of this driver.  The
day-of-week value reported by time.localtime() has been fixed, memory
corruption when a thread is created on core1 has been fixed, and the UART
now uses a mutex when reading/writing to prevent character duplication in
code that uses both cores.

The stm32 port has added support for G0, G4 and WL MCUs.  The new boards
for these MCUs are NUCLEO_G0B1RE, NUCLEO_G474RE and NUCLEO_WL55.  The
ARDUINO_PORTENTA_H7 board has also been added, with full WiFi and BLE
support.  The rfcore on WB55 MCUs has been improved by removing an extra
layer of buffering, and the restriction on the use of address resolution
has been removed, meaning that the rfcore WS firmware should be updated
to v1.12.0 or later; see commit 26b1d31eda292d9cd5cfc68f14ce8055256fade8.
The board-level configuration of mboot has been significantly improved to
allow more control over system clocks, more hooks into the start up
process, and a hook for state change.  And the CRC32 of DFU files is now
verified before writing them.

The pyb.CAN class has been improved to support FD frames and buses with
mixed classic/extended-ID nodes, allowing extended IDs to be specified on a
per-message basis.  CAN.recv also now returns a value indicating if the
received message had an extended ID or not.  And CAN.initfilterbanks has
been removed, replaced with the num_filter_banks keyword argument to
CAN.init.  These are all breaking changes to the pyb.CAN class API and code
will need to be updated accordingly; see commit
5cdf9645711cc12b45e602ef5795c33895116fc4 for details.

The unix port now shows compiler information in the REPL banner to make it
consistent with how bare-metal ports work, and the "-X realtime"
command-line option has been added for macOS to get improved timing.  All
variants have switched to use the VFS subsystem, and use the VfsPosix class
for mounting the host's filesystem.  The os module has been consolidated
with all other ports and the minimal and standard variants gain the unlink,
chdir, getcwd and listdir functions.

The windows port has also switched to the VFS subsystem and VfsPosix.  It
adds support for micropython.schedule and uasyncio on the dev variant.  And
BCryptGenRandom has been used to implement os.urandom.

The zephyr port upgraded Zephyr to v3.0.0.

The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):

       bare-arm:   +792  +1.394%
    minimal x86:  +2091  +1.286%
       unix x64: +10231  +1.995%
    unix nanbox:  +9777  +2.162%
          stm32:   +184  +0.047% PYBV10
         cc3200:   +904  +0.493%
        esp8266:  -1240  -0.177% GENERIC
          esp32:  +6464  +0.425% GENERIC
            nrf: +11288  +6.472% pca10040
            rp2: +14432  +2.929% PICO
           samd:  +1352  +0.970% ADAFRUIT_ITSYBITSY_M4_EXPRESS

The changes that dominate these numbers are:
- bare-arm, minimal, cc3200, samd: reworked bytecode and mpy format,
  optimisation of jump opcodes to use 1-byte offsets, de-duplication of
  constants at the module level, and PEP 448 support
- unix: switching to use VFS, and new mpy format and related changes
- esp8266: removal of esp.info and machine.WDT.deinit
- esp32: addition of machine.ADCBlock, and new mpy format changes
- nrf: enabling uasyncio, enabling MICROPY_PY_IO
- rp2: enabling ucryptolib with mbedtls

Note that the stm32 port's size remained roughly unchanged.  This is
because it has a decent amount of frozen Python code and the reduction in
frozen code size due to the reworked bytecode has offset the increase in
runtime/VM size due to this change.  Ports like bare-arm, minimal, cc3200
and samd do not have any frozen code so only see the increase in runtime/VM
size.  Production-level projects that have a significant amount of frozen
code have seen around a 4% overall reduction in their firmware size.

Thanks to everyone who contributed to this release: Algy Tynan, Andrew
Leech, Andrew Scheller, Artyom Skrobov, Asensio Lorenzo Sempere, Bradley
Wogsland, Cem Eliguzel, Chris Wilson, Christian Decker, Christian Zietz,
Christophe Priouzeau, Clayton Mills, Damien George, Daniel Jour, Daniël van
de Giessen, Dave Hylands, David Lechner, Emil Kondayan, Herwin Grobben,
iabdalkader, IhorNehrutsa, Jan, Jared Hancock, jason, Jeff Epler, Jeremy
Herbert, Jim Mussared, Jon Bjarni Bjarnason, Jonathan Hogg, Jos Verlinde,
Kattni Rembor, Lars Kellogg-Stedman, Luiz Brandao, marcidy, Martin Fischer,
Maureen Helm, Meriç SARIIŞIK, Michael Himing, Michael O'Cleirigh,
MikeTeachman, Peter D. Gray, Peter Hinch, Peter Züger, Phil Howard, Philipp
Ebensberger, Rob Knegjens, robert-hh, Sean Coates, Seon Rozenblum, Stephane
Smith, stijn, Takeo Takahashi, ubi de feo, Waterlens, wemos, YoungJoon
Chun, Yukai Li.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- fix MICROPY_OBJ_REPR_D compilation with msvc
- update Python formatting to latest Black version 22.1.0
- use mp_obj_malloc everywhere it's applicable
- reformat remaining C code that doesn't have a space after a comma
- remove third argument to MP_REGISTER_MODULE
- rename MICROPY_PY_WIZNET5K to MICROPY_PY_NETWORK_WIZNET5K

py core:
- objstr: support '{:08}'.format("Jan") like Python 3.10
- modmath: add math.tau, math.nan and math.inf constants
- qstr: separate hash and len from string data
- qstr: use `const` consistently to avoid a cast
- gc: update debug code to compile with changes to qstr pool types
- rework bytecode and .mpy file format to be mostly static data
- bc.h: fix C++ compilation of public API
- objmodule: support delegating failed attr lookups
- modsys: add optional attribute delegation
- modsys: add optional sys.tracebacklimit attribute
- modsys: add optional mutable attributes sys.ps1/ps2 and use them
- parse: simplify handling of const int parse nodes
- parse: put const bytes objects in parse tree as const object
- parse: handle check for target small-int size in parser
- showbc: remove global variables and make DECODE_PTR work correctly
- smallint: introduce MP_SMALL_INT_BITS macro
- objgenerator: fix unused variables when native gen extracts prelude
- change jump opcodes to emit 1-byte jump offset when possible
- emitbc: add check for bytecode jump offset overflow
- change jump-if-x-or-pop opcodes to have unsigned offset argument
- builtinimport: alias sys to usys if import weak links aren't enabled
- bc.h: fix C++20 compilation with "volatile"
- compile: only show raw code that is bytecode
- asmxtensa: fix use of l32i/s32i when offset won't fit in encoding
- emitnative: don't store prelude at end of machine code if not needed
- vm: prevent array bound warning when using -MP_OBJ_ITER_BUF_NSLOTS
- runtime: allow multiple **args in a function call
- runtime: allow multiple *args in a function call
- runtime: do not overallocate when len is known
- runtime: drop new_alloc < 4 check
- runtime: use size_t/ssize_t instead of uint/int
- emitbc: assert that a small int fits its encoding when emitting one
- fix compiling and decoding of *args at large arg positions
- runtime: remove unnecessary check for kw_value == MP_OBJ_NULL
- makeqstrdefs: cleanup and extend source file classification
- emitinlinethumb: use 16 bit encodings for PUSH LR and POP PC
- scheduler: add support for scheduling static C-based callbacks
- emitnative: revert "don't store prelude at end of machine code if..."
- persistentcode: define enum values for obj types instead of letters
- parse: factor obj extract code to mp_parse_node_extract_const_object
- parse: print const object value in mp_parse_node_print
- parse: add MICROPY_COMP_CONST_TUPLE option to build const tuples
- persistentcode: support loading and saving tuples in .mpy files
- objtype: convert result of user __contains__ method to bool
- modsys: append MicroPython git version and build date to sys.version
- modsys: rename sys.implementation.mpy to sys.implementation._mpy
- modsys: introduce sys.implementation._machine constant
- emitcommon: don't implicitly close class vars that are assigned to
- obj: introduce mp_obj_malloc macro to allocate, and set object type
- objfloat: explain why mp_obj_malloc isn't used
- malloc: introduce m_tracked_calloc, m_tracked_free functions
- objmodule: move stray #include to top of file
- persistentcode: remove obsolete comment about qstr window size
- persistentcode: remove unicode feature flag from .mpy file
- asmx64: support full range of regs in asm_x64_lea_disp_to_r64
- bc: provide separate code-state setup funcs for bytecode and native
- emitnative: put a pointer to the native prelude in child_table array
- compile: allow new qstrs to be allocated at all compiler passes
- compile: de-duplicate constant objects in module's constant table
- parse: allow all constant objects to be used in "X = const(o)"
- makemoduledefs.py: allow multiple ways to register a module
- make builtin modules use MP_REGISTER_MODULE
- remove support for MICROPY_PORT_BUILTIN_MODULES
- asmthumb: fix PC relative load by sign extending the constant
- emitnative: simplify generation of code that loads prelude pointer
- emitnative: provide dedicated local for exception unwind handler ptr
- asmthumb: fix offset variable name in ldr, ldrh and strh functions
- asmthumb: add asm_thumb_ldrh_reg_reg_i12_optimised() helper func
- asmarm: add asm_arm_ldrh_reg_reg_offset() helper func
- asm: add ASM_LOAD16_REG_REG_OFFSET macro for load-u16 with offset
- emitnative: access qstr values using indirection table qstr_table
- asmthumb: make ARMv7-M instruction use dynamically selectable
- persistentcode: select ARMV6M as maximum when __thumb2__ not defined
- dynruntime.mk: add basic support for armv6m architecture
- asmthumb: provide implementations of clz/ctz for msvc
- builtin: clean up and simplify import_stat and builtin_open config
- emitinlinethumb: make ARMv7-M instruction use dynamically selectable
- emitinlinethumb: make float instruction use dynamically selectable
- change makemoduledefs process so it uses output of qstr extraction
- persistentcode: remove remaining native qstr linking support
- bc: remove unused mp_opcode_format function
- compile: give the compiler a hint about num nodes being non-zero
- makemoduledefs.py: remove shebang line and adjust style of comment
- parse: work around xtensa esp-2020r3 compiler bug
- dynruntime: add macros to create a new dict and store to dicts
- dynruntime: add macros to access more types and mp_const_empty_bytes
- makemoduledefs.py: emit useful error for legacy MP_REGISTER_MODULE

extmod:
- network_ninaw10: implement MP_STREAM_POLL in ioctl
- modusocket: make setsockopt return if NIC is not connected
- modusocket: add makefile() method and common socket options
- modusocket: create new sockets in blocking mode
- modusocket: support additional args to getaddrinfo
- machine_i2c: increase default SoftI2C timeout to 50ms
- modubinascii: add newline keyword to b2a_base64 function
- moduplatform: move platform PP definitions into a header
- moduzlib: fix parsing zlib header dict size
- moduos: create general uos module to be used by all ports
- modure: set subject begin_line so ^ doesn't match interior
- uasyncio: allow task state to be a callable
- uasyncio: fix gather cancelling and handling of exceptions
- extmod.cmake: add micropy_lib_mbedtls component
- modusocket: implement optional socket.listen backlog argument
- modusocket: provide config macro for socket.listen backlog deflt
- uasyncio: make Python Task match C version with use of asserts
- uasyncio: fix bug with task ending just after gather is cancel'd
- uasyncio: rename and merge TaskQueue push/pop methods
- move font_petme128_8x8.h from ports/stm32 to extmod
- make extmod modules use MP_REGISTER_MODULE
- make port-included extmod modules use MP_REGISTER_MODULES
- revert accidental usocket->socket rename
- webrepl: fix setting password in foreground mode and factor code
- modusocket: fix polling of a new socket
- modusocket: bind unconnected socket to default NIC in setsockopt
- modusocket: fix errcode returned from socket read/write
- modusocket: add socket type print function
- modusocket: add support for socket events callback
- modusocket: fix socket_make_new argument parsing
- modusocket: add timeout and callback to socket object
- modusocket: add sendall function
- network_ninaw10: add support for socket events callback
- machine_i2c: add optional support for write-then-read transfers
- uasyncio: fix edge case for cancellation of wait_for
- nimble: add support for reading whole HCI UART packets
- network_wiznet5k: add Wiznet Ethernet network interface
- modussl_mbedtls: poll EVENT_POLL_HOOK in ssl handshake loop
- modurandom: fix missing void in empty argument list
- extmod.cmake: require components to be explicitly enabled
- modusocket: add socket state to track new/listening/conn/closed
- modusocket: fix polling of closed sockets
- extmod.cmake: fix hard-coded mbedtls config file path

shared:
- readline: make tab insert an indent when it follows whitespace
- readline: disable auto-indent if space/tab follows added indent

drivers:
- ninaw10: add function to check socket state/data availability
- ninaw10: fix timeout handling to match modusocket
- ninaw10: return standard error numbers
- ninaw10: add NIC-level ioctl function
- sdcard: allow setting the final SPI baudrate
- codec: add driver for the WM8960 codec
- ninaw10: fix isconnected to return False when inactive
- dht/dht.py: change default import module as machine
- ninaw10: update driver to support firmware 1.5.0
- bus: rename MP_SPI_ADDR_IS_32B to MICROPY_HW_SPI_ADDR_IS_32BIT
- lsm6dsox: add support for SPI mode
- sdcard: fix CSD version 1.0 device size calculation
- sdcard: make ioctl(4), ioctl(5) return num blocks, block size
- sdcard: fix address calculation on v2 SDSC cards

mpy-cross:
- add armv6m architecture option

lib:
- re1.5: distinguish between subject start-of-line and start-of-srch
- stm32lib: update library for G0 v1.5.1
- fsp: add renesas fsp git repository as submodule
- littlefs: update littlefs2 to v2.5.0
- littlefs: guard lfs2_file_rawopen with LFS2_NO_MALLOC
- littlefs: remove assignment of variables to themselves
- nxp_driver: update nxp_driver to v2.10
- wiznet5k: add submodule for Wiznet Ethernet drivers

Support components
==================

docs:
- library: specify additional ADC methods and new ADCBlock class
- esp32: document expanded ADC API in quickref
- differences: update differences now that math.tau/inf/nan exist
- differences: update python_36 now that b2a_base64 accepts newline
- remove reference to obsolete neopixel_write function
- develop/porting.rst: fix build and import problems in the example
- reference/isr_rules.rst: fix inconsistent variable name in example
- esp32/quickref: update ADC documentation
- reference/isr_rules.rst: describe uasyncio-IRQ interface
- library/collections.rst: use class for deque and OrderedDict
- use the correct * keyword-only notation
- library/socket.rst: document socket as a class
- library/pyb.Timer.rst: add pyb.Timer class constants
- library/pyb.rst: add pyb.hid_mouse and pyb.hid_keyboard constants
- library/pyb.DAC.rst: add DAC class constants
- library/machine.SPI.rst: add class constant SoftSPI.MSB and .LSB
- library/machine.WDT.rst: use correct case for WDT.feed
- library/esp.rst: document the osdebug function
- library/pyb.SPI.rst: document default for prescaler argument
- library/machine.Pin.rst: document defaults for Pin.init
- library/uasyncio.rst: fix description of ThreadSafeFlag.wait
- library/machine.UART.rst: add details for `invert` parameter
- differences/python_35: mark PEP 486 as not applicable
- library/esp32.rst: mark esp32.Partition as not taking kw args
- esp32/quickref: document GPIO drive strength
- library/machine.Pin: update to use preferred DRIVE_x constants
- esp32/quickref: refine deep-sleep power-saving notes
- library/machine.I2S: clarify what rate refers to
- library/pyb.CAN: update CAN docs to match revised API
- add quickref and docs for mimxrt, including network.LAN docs
- reference/mpremote: add details about mount usage over soft reboot
- differences: update Python 3.5 diff, with optional listen backlog
- reference: update constrained docs now that tuples can be const
- library/network.WLAN: add "txpower" to list of known WLAN configs
- renesas-ra: add renesas-ra docs files
- update files for renesas-ra port
- renesas-ra: remove unused image files
- reference/mpyfiles: remove docs about mpy flags and qstr win size
- mimxrt: add i.MX RT1015 to general.rst, and a few clarifications
- mimxrt: move the pinout tables to a separate document
- reference/manifest: add link to details about opt-level for freeze
- reference/mpyfiles: update .mpy description to match latest format
- update Raspberry Pi URLs from .org to .com

examples:
- embedding: fix build with updated sys and os modules
- natmod/features3: add example to test more natmod features

tests:
- run-multitests.py: ignore lld_pdu_get_tx_flush_nb msgs from IDF
- run-multitests.py: set HOST_IP so tests work between PC and board
- multi_net: add testing key/cert to SSL server/client test
- multi_net: close accepted sockets when tests are done
- multi_net/udp_data.py: allow reusing port before bind
- multi_net/udp_data.py: make UDP test more reliable
- run-perfbench.py: allow a test to SKIP, and to have a .exp file
- perf_bench: add perf tests for qstr interning and importing .mpy
- perf_bench: add perf test for yield-from execution
- run-perfbench.py: use SKIP consistently, and increase print width
- extmod/vfs_fat_finaliser.py: make finalisation more robust
- run-tests.py: skip repl tests when running windows underneath
- perf_bench: skip bm_chaos test if random.randrange is unavailable
- unix: add coverage test for freezing various objects
- basics: add test for creating small-ints in nan-box builds
- run-tests.py: include test files ending in _set as set tests
- micropython: switch from set.pop to raise-0 to test exc strings
- extmod/vfs_posix.py: only test statvfs if it exists
- cmdline/cmd_showbc: fix spelling of sequence
- extmod: add test for machine.I2S data rate
- extmod: update I2S rate test to work on mimxrt
- basics/fun_callstardblstar: add coverage test
- basics/fun_callstardblstar: add test for large arg allocation
- pyb: update CAN tests to match revised CAN API
- inlineasm: add test for PUSH LR and POP PC
- perf_bench: update import tests for changes to .mpy consts
- micropython: add tests that const tuples don't use the heap
- extmod/uasyncio_gather: make double-raise gather test reliable
- run-tests.py: add timeout for running PC-based MicroPython test
- cmdline: add test for REPL auto-indent
- renesas-ra: add tests for renesas-ra port
- run-tests.py: update for renesas-ra port
- renesas-ra: remove unsupported feature test of Pin
- extmod: increase timing on uasyncio tests to make more reliable
- fix tests to use sys.implementation._mpy
- perf_bench: update .mpy file header to remove old unicode flag
- run-perfbench.py: return error code if any test fails on target
- thread: use less resources for stress_aes if settrace enabled
- run-tests.py: exclude settrace tests when using native emitter
- multi_net: skip SSL test if relevant modules aren't available
- micropython: fully unlink nested list in extreme exc test
- extmod: use bytearray instead of bytes for uctypes test
- micropython: add more test cases for native generators
- run-tests.py: allow running tests via mpy-cross on remote targets
- run-perfbench.py: allow running tests via mpy and native emitter
- basics: unlock heap if skipping nanbox small-int test
- run-tests.py: handle case where mpy-cross fails to compile script
- run-tests.py: enable `-X realtime` option for macOS tests
- extmod: change expected errno code from 36 to 30 in VfsLfs2 test
- multi_net: fix TCP accept test when using system error numbers
- run-multitests.py: use LAN for IP address if WLAN doesn't exist
- micropython: make import_mpy_native_gc run on ARMv6-M and above
- micropython: make import_mpy_native test run on all architectures
- run-tests.py: add rp2 test target
- move native while test from pybnative to micropython
- net_inet: remove broken api.telegram.org from tests
- run-multitests.py: read IP address from boot nic if available
- basics: add .exp file for sys.tracebacklimit test
- stress: adjust bytecode_limit test so it can SKIP if no memory

tools:
- mpremote: use machine instead of umachine in commands
- ci: test math constants with MICROPY_OBJ_REPR_D
- uf2conv.py: update to latest version
- autobuild: provide .uf2 images for esp32 builds when available
- mpremote: fix "fs cp -r" on Windows
- mpremote: make ConsolePosix work without .raw attribute
- mpremote: during soft reboot wait long enough for 115200 data
- mpremote: accept both --help and help to show usage
- mpremote: correctly manage mounted flag during soft-reset
- mpremote: fix special handling of ctrl-D when host FS is mounted
- verifygitlog.py: ignore line length in body if it's a URL
- ci.sh: update IDF v4.4 build to use v4.4 tag
- ci.sh: run urandom test scripts as part of native module tests
- mpremote: add "resume" and "soft-reset" commands
- mpremote: add "umount" command
- upip.py: remove unused op_basename() function
- mpy-tool.py: fix frozen comment generation to escape chars
- ci.sh: run performance benchmark as part of all unix test runs
- mpremote: bump version to 0.2.0
- gen-cpydiff: skip Black fmt comments
- mpremote: support any prompt string when detecting soft reset
- mpremote: allow running mpremote with `python -m`
- mpremote: improve reliability of mount after soft reboot
- mpremote: show progress indicator when copying large files
- mpremote: add option to mount cmd to allow "unsafe" symlinks
- mpy-tool.py: support loading tuples from .mpy files
- mpy-tool.py: support freezing tuples and other consts
- mpy-tool.py: optimise freezing of ints that can fit a small int
- mpy-tool.py: optimise freezing of empty str and bytes objects
- mpy-tool.py: make global qstr list a dedicated class
- mpy-tool.py: optimise freezing of str when str data is a qstr
- mpy-tool.py: intern more strings when freezing
- codeformat.py: remove ports/unix/*.py from exclusion list
- codeformat.py: include more ports .c/.h files in formatting
- ci.sh: don't run uasyncio_gather test on macOS
- ci.sh: update for ports/renesas-ra
- uncrustify: make sure a space exists after a comma
- autobuild: update for ports/renesas-ra
- mpy_ld.py: remove obsolete QSTR_WINDOW_SIZE constant
- ci.sh: run full test suite on stackless and settrace builds
- ci.sh: for esp8266 CI install esptool 3.3.1
- mpy-tool.py: remove obsolete unicode flag in .mpy header
- ci.sh: add build of W5100S_EVB_PICO board to rp2 CI
- mpy-tool.py: rework .mpy merging feature
- ci.sh: add test for mpy-tool's merging feature
- mpy-tool.py: improve generated frozen identifiers
- mpremote: add command to print the version
- mpremote: bump version to 0.3.0
- ci.sh: build NUCLEO_H743ZI with -O2 optimisation level
- mpy_ld.py: support R_XTENSA_PDIFF32 relocation
- ci.sh: build native .mpy examples for armv7emsp, xtensawin in CI
- mpy_ld.py: support GOT entries that reference inside mp_fun_table

CI:
- workflows: show context for qemu-arm test failures
- workflows: add new workflow to test .mpy file format and tools
- workflows: add new workflow to test embedding example
- workflows: add workflow for renesas-ra port

The ports
=========

all ports:
- consolidate inclusion of umachine module in built-ins
- recompile bytecode tests now that .mpy format changed
- allow boards to define additional network interfaces
- recompile bytecode tests now that .mpy format changed
- reformat more C and Python source code
- rename thread_t to mp_thread_t
- use default VFS config for import_stat and builtin_open

bare-arm port: no changes specific to this component/port

cc3200 port:
- make port-specific modules use MP_REGISTER_MODULE

esp8266 port:
- moduos: convert module to use extmod version
- mpconfigport.h: remove config values that are the defaults
- modesp: remove esp.info() function
- make port-specific modules use MP_REGISTER_MODULE
- machine_wdt: remove deinit method for watchdog
- etshal.h: remove unneeded function declaration

esp32 port:
- machine_adcblock: add new machine.ADCBlock class and update ADC
- pin MicroPython to core 1 again
- esp32_rmt: call rmt_driver_install directly if running on core 1
- main: allocate at most 1/2 of available IDF heap for MP heap
- README.md: fix URL for esp-idf installation
- modnetwork: fix test for WIFI_AUTH_MAX for IDF v4.3.0
- main: use heap_caps_get_info on IDF <4.1 to compute total heap
- boards: provide custom deploy_c3.md for ESP32-C3 boards
- partitions: increase size of app-part from 0x180000 to 0x1F0000
- machine_pwm: fix PWM not allowing frequencies < 611 Hz
- machine_pwm: clean up macro names and their use
- esp32_rmt: select correct last RMT channel on S2, S3, C3 variants
- main: automatically size SPIRAM heap when allocated using malloc
- adc: fix wrong mapping between ADC2 channel and GPIO number
- remove unneeded modesp.h
- create .uf2 binaries for S2 and S3 chips
- partitions-16MiB.csv: increase 14MiB filesystem to maximum size
- machine_adcblock: fix ADC bit width for ESP32-S3
- machine_adc: fix configuration of default ADC atten value
- boards: add three UM ESP32-S3 based boards
- mpconfigport.h: use the "extra" feature level
- mpconfigport.h: enable remaining features to get to "extra" level
- esp32_partition: add support for specifying block_size
- modules: create ffat partition object with block_size=512
- README.md: update list of supported IDF versions
- boards: add specific deploy instructions for S3 variant
- uart: correctly init low-level UART driver for REPL
- machine_uart: allow limited configuration of REPL UART
- sleep one tick in MICROPY_EVENT_POLL_HOOK
- machine_pwm: always set the duty cycle when setting the frequency
- machine_uart: make UART.init preserve unspecified parameters
- machine_pin: add support for pin drive strength
- moduos: convert module to use extmod version
- machine_pin: add new hold keyword argument and remove PULL_HOLD
- modesp32: add new gpio_deep_sleep_hold function
- boards/UM_TINYPICO: remove use of PULL_HOLD
- boards: add LOLIN C3 MINI ESP32-C3 based board
- machine_hw_spi: use automatic DMA channel selection for SPI on C3
- boards: add support for LilyGO LoRa32 boards
- machine_pin: expose pin 20 for ESP32
- allow overriding cmake frozen manifest from the command line
- boards: add test manifest to test freezing during build
- add MICROPY_HW_ENABLE_UART_REPL and enable on generic S2/S3
- boards: compile GENERIC_SPIRAM and UM_TINYPICO with -Os
- machine_pin: don't expose pins 33-37 when octal SPIRAM is enabled
- modesp32: properly define RTC_VALID_EXT_PINS on S2/S3 variants
- network_wlan: support setting/getting txpower in WLAN.config()
- modnetwork: fix build when MICROPY_PY_NETWORK_WLAN is disabled
- make port-specific modules use MP_REGISTER_MODULE
- boards/UM_FEATHERS3: use correct sdkconfig.board
- boards/LILYGO_TTGO_LORA32: remove ID from TTGO Lora32 board json
- machine_pin: fix ESP32C3 IDFv4.4.1 build
- track allocated iRAM and free it on soft reset
- machine_i2c: implement write-then-read I2C transfers
- machine_pin: only expose IO20 on esp32 for IDF 4.3.2 and above

javascript port:
- make port-specific modules use MP_REGISTER_MODULE

mimxrt port:
- support gaps in the SPI an I2C device numbers
- allow for board-specific flash driver files
- compensate for a bug in the fsl_lpspi.c file
- remove two files from the Seeed Arch Mix directory
- replace Pin-config constants by a function call
- allow to select cs0 or cs1 for SPI
- add USB ID elements
- add support for the Olimex RT1010 board
- simplify Makefile in selection of flash type
- machine_pin: change pin drive constants to DRIVE_x naming
- machine_spi: add omitted GPIO config
- boards: add board files for MIMXRT1015 and MIMXRT1015_EVK
- eth: fix an Ethernet transmit error
- boards/TEENSY41: use the same SPI1 pins for Teensy 4.0 and 4.1
- boards: support using an optional board-specific manifest.py
- eth: avoid a race condition for Ethernet
- hal/pwm_backport: make PWM symmetric, and round division calcs
- moduos: convert module to use extmod version
- mbedtls: add NULL pointer check in m_free_mbedtls
- machine_i2s: add I2S protocol support
- boards: add board.json file for OLIMEX RT1010Py
- modules: append /flash/lib to the default sys.path
- machine_rtc: start RTC at boot and set datetime if not set
- machine_spi: improve handling of busy SPI peripheral
- mphalport: fix USB CDC RX handling to not block when unprocessed
- mbedtls: use core-provided tracked alloc instead of custom funcs
- make port-specific modules use MP_REGISTER_MODULE
- boards/OLIMEX_RT1010: document the initial deploy procedure
- boards: extend the deploy_teensy.md instructions
- mphalport: fix strict aliasing error with unique id
- update port to work with new nxp_driver v2.10
- machine_uart: fix an inconsistency for UART.init() arg handling

minimal port: no changes specific to this component/port

nrf port:
- drivers/usb: fix background events/scheduling while at USB REPL
- drivers/usb: fix MP_STREAM_POLL_RD support on USB CDC
- modules: include uasyncio in default board manifest
- make port-specific modules use MP_REGISTER_MODULE
- mpconfigport: set MICROPY_CONFIG_ROM_LEVEL defines for each MCU
- mpconfigport: enable extra features as defined by ROM levels
- mpconfigport: fix MICROPY_VFS IO build support
- modules/uos/microbitfs: fix MICROPY_MBFS build to use mp_obj_malloc

pic16bit port:
- make port-specific modules use MP_REGISTER_MODULE
- use 1 byte for qstr hash len and include header to fix build

powerpc port: no changes specific to this component/port

qemu-arm port:
- add tests for freezing viper and asm_thumb code
- moduos: convert module to use extmod version
- test-frzmpy: add test for freezing constant tuples
- mpconfigport: define MICROPY_PY_SYS_PLATFORM

renesas-ra port:
- add new port to Renesas RA
- boards: change device name information to show properly
- rename pyb_uart_ to machine_uart_
- rename pyb_rtc_ to machine_rtc_
- make port-specific modules use MP_REGISTER_MODULE
- modmachine: add missing MP_REGISTER_MODULE for umachine
- machine_pin: remove code for unsupported Pin features

rp2 port:
- machine_i2c: provide more specific error codes from I2C transfer
- mpconfigport.h: use internal error numbers
- mphalport: add optional dupterm support
- machine_uart: add machine.UART init/deinit methods
- machine_i2c: use soft I2C only for len=0, and increase timeout
- modutime: fix time.localtime day-of-week value
- machine_uart: fix UART RTS behaviour so RTS is deasserted
- Makefile: add FROZEN_MANIFEST Makefile option, to override default
- mpthreadport: fix memory corruption when thread is created in core1
- add USB MSC support
- allow Overriding cmake frozen manifest from the command line
- enable ucryptolib, using mbedtls for backend functions
- mphalport: fix USB CDC RX handling to not block when unprocessed
- Makefile: add mbedtls to GIT_SUBMODULES list and use it in CI func
- machine_uart: use read/write mutex to prevent char duplication
- mpconfigport: enable execfile, NotImplemented and REPL EMACS keys
- make port-specific modules use MP_REGISTER_MODULE
- mpconfigport.h: enable static scheduler nodes
- mpconfigport.h: allow boards to override internal errno config
- boards/ARDUINO_NANO_RP2040_CONNECT: disable internal errno
- boards/ARDUINO_NANO_RP2040_CONNECT: enable webrepl
- mbedtls: add support for ssl module with MICROPY_SSL_MBEDTLS
- machine_pin: add mp_hal_pin_interrupt C interface
- Makefile: use cmake for "make submodules" task when needed
- integrate lwIP network stack
- add support for using Wiznet hardware as an Ethernet NIC
- boards/W5100S_EVB_PICO: add Wiznet W5100S-EVB-Pico board
- Makefile: build in debug mode with "make DEBUG=1"
- boards/ARDUINO_NANO_RP2040_CONNECT: update USB PID
- mpnetworkport: fix lwip alarm callback timing to use microseconds
- CMakeLists: simplify qstr sources when enabling extmod components

samd port:
- moduos: convert module to use extmod version
- make port-specific modules use MP_REGISTER_MODULE

stm32 port:
- mbedtls: enable MBEDTLS_TLS_DEFAULT_ALLOW_SHA1_IN_KEY_EXCHANGE
- mboot: remove custom HAL_RCC_GetHCLKFreq and use HAL provided one
- pin: change remaining uses of "af" to "alt"
- dac: deinit all DACs on soft reset
- fdcan: fix FIFO1 usage and handling of error interrupts
- fdcan: fix naming with regards to G4 series
- usbd_conf: set lpm_enable and battery_charging_enable on all MCUs
- powerctrlboot: set HAL uwTickPrio variable when needed
- powerctrl: write bootloader-state as 64-bit word to work on H7
- mboot: use PLL3 for USB clock source on H7 MCUs
- mboot: include hal_rcc_ex.c in source file list
- mboot: support H7 MCUs in fwupdate.py
- mboot: compute and check CRC32 of dfu file in fwupdate.py
- add support for G4 MCUs, and add NUCLEO_G474RE board defn
- mboot: allow HSI to be used as the main clock source
- mboot: add MBOOT_BOARD_ENTRY_INIT for a board to add entry code
- mboot: add support for F469/479 MCUs in fwupdate.py
- rtc: use LL_RTC functions to simplify some MCU-specific code
- Makefile: make stm32lib configurable
- add initial support for STM32WL MCUs
- boards/NUCLEO_WL55: add new board definition
- system_stm32: make SystemClock_Config() a weak symbol
- adc: fix L4 ADC channel numbers
- adc: remove obsolete FIRST/LAST GPIO channel macros
- boards/NUCLEO_L432KC: disable MICROPY_OPT_COMPUTED_GOTO
- boards/NUCLEO_WB55: add Arduino pin alias definitions
- mboot: allow a board to fully configure system clocks
- mboot: allow a board more control over entry initialisation
- moduos: convert module to use extmod version
- boards: convert F4xx and F7xx to new flash FS config
- mbedtls: add NULL pointer check in m_free_mbedtls
- sdcard: use mp_hal_pin_input instead of HAL function
- sdcard: add sdcard_select_sd/mmc functions
- main: support SD cards without a partition table
- dma: add option to disable auto-DMA-turn-off
- mboot: add pragma for GCC to ignore array bounds warning
- mboot: always check the magic number to enter filesystem loading
- mboot: add support for 64-bit mboot address space for reads
- mboot: add support for reading from SD card
- boards/PYBD_SF2: turn on SD card in mboot init if SD enabled
- mboot/fwupdate.py: simplify calculation of CRC32
- mboot: verify signature of fsload packed DFU files before writing
- mboot: verify CRC32 of fsload DFU files before writing
- support building for STM32F745
- machine_i2s: set FullDuplexMode to disabled on F4
- machine_i2s: allow I2S.deinit to be called multiple times
- machine_i2s: fix 16-bit stereo i2s_frame_map
- sdio: use runtime calculation for clock divider of sdio on H7
- modmachine: add deepsleep support to reset_cause() for WB55
- pyb_can: enable CAN FD frame support and BRS
- pyb_can: add support for CAN FD extended frame ID
- pyb_can: add support for bus with mixed Classic/FD nodes
- pyb_can: return the filter ID and type of received messages
- pyb_can: define the maximum bit timing parameters
- pyb_can: replace CAN.initfilterbanks with CAN.init keyword arg
- Makefile: allow overriding COPT in Makefile
- mpconfigport.h: let MICROPY_PY_IO_FILEIO take its default value
- machine_bitstream: include all clobbered regs in Cortex-M0 impl
- mboot: consolidate all UI and add general state change hooks
- mboot: add macros for use in led_state_all()
- sdram: add function to enable SDRAM power-down mode
- Makefile: add H747 to Makefile's MCU flags
- system_stm32: add H7 switched-mode-power-supply support
- system_stm32: set voltage scaling level 0 for H7 Rev-V devices
- system_stm32: allow boards to configure PLL VCI, VCO and FRACN
- system_stm32: improve H7 PLL and OSC configuration
- boards/PYBD_SFx: allow FROZEN_MANIFEST to be overridden
- mpbthciport: switch scheduling callback to use node scheduler
- boards/SPARKFUN_MICROMOD_STM32: fix incorrect UART and I2C config
- mphalport: fix I/O glitches when switching GPIO mode to alt-func
- boards/ADAFRUIT_F405_EXPRESS: use external SPI flash for storage
- boards/LEGO_HUB_NO6: exclude BTstack code from formatting
- qspi: support common flash sizes in MPU configuration
- qspi: wait for a free FIFO location before writing to DR
- qspi: workaround for SR set immediately after setting AR
- ulpi: add USB3320 ULPI low-power functions
- ulpi: include missing py/mperrno.h header
- boards/ARDUINO_PORTENTA_H7: add support for Arduino Portenta H7
- storage: add support for internal storage on Cortex-M0 MCUs
- add support for G0 MCUs
- boards/NUCLEO_G0B1RE: add NUCLEO_G0B1RE board definition
- mbedtls: use core-provided tracked alloc instead of custom funcs
- make port-specific modules use MP_REGISTER_MODULE
- rfcore: revert "intercept addr-resolution HCI cmd to work arou..."
- mboot: move remaining led_state_all call into mboot_state_change
- mboot: add update_app_elements to return mboot fsload elements
- mboot: make 0x70ad0000 values named constants with macros
- mboot: pass initial_r0 to early-init and get-reset-mode funcs
- boards/LEGO_HUB_NO6: make all SPI flash transfers use 32-bit addr
- boards/LEGO_HUB_NO6: add support for mboot to access SPI flash
- boards/LEGO_HUB_NO6: use multi-colour LED for mboot status
- boards/LEGO_HUB_NO6: implement robust filesystem-load updates
- boards/LEGO_HUB_NO6: add helper scripts to update app firmware
- rfcore: remove extra layer of buffering on BLE IPCC
- flash: remove FLASH_OPTR_DBANK condition in L4, H7 get_bank func
- machine_i2c: enable timingr constructor keyword on H7 MCUs
- powerctrl: disable sys tick interrupt in stop mode on some STM32s
- usbd_conf: remove disable of SYSCFG clock
- mboot: add board-configurable SysTick hook
- mboot: remove MP_WEAK on led funcs and make some of them static
- boards/LEGO_HUB_NO6: add comment to readme about powering off
- mboot: only include UI code if at least one board LED is defined

teensy port:
- make port-specific modules use MP_REGISTER_MODULE
- mpconfigport.h: remove obsolete macros

unix port:
- Makefile: remove explicit addition of -std=c++ flag
- show compiler info in REPL banner
- .gitignore: remove *.py from ignore list
- moduos: convert module to use extmod version
- mpconfigport.h: collect together config options from extra level
- variants: use rom feature config for standard, dev, coverage
- variants: enable a few optimisations and features on dev, coverage
- make port-specific modules use MP_REGISTER_MODULE
- implement `-X realtime` command-line option on macOS
- factor out code that generates random bytes to a new func
- variants: enable seeding random module on import in dev, coverage

windows port:
- README.md: fix broken mingw link
- add micropython.schedule support
- mingw: include extmod/shared/lib sources properly
- uselect: enable micropython select in dev variant
- uasyncio: add support for uasyncio to windows dev variant
- appveyor: fix printing of test failures
- Makefile: specify CXXFLAGS in the Makefile
- unify project file headers
- switch to VFS subsystem and use VfsPosix
- consolidate all sleep-related functions into windows_mphal.c
- avoid busy loop when using scheduler
- use BCryptGenRandom to implement os.urandom
- factor out code that generates random bytes to a new func

zephyr port:
- update include path to disk_access.h
- upgrade to Zephyr v3.0.0
- prj.conf: enable CONFIG_BUILD_OUTPUT_HEX to generate .hex output
- moduos: convert module to use extmod version
- make port-specific modules use MP_REGISTER_MODULE
- modusocket: fix function object wrapper for listen method

Boosted performance, board.json metadata, more mimxrt, rp2, samd features

This release of MicroPython sees a boost to the overall performance of the
VM and runtime.  This is achieved by the addition of an optional cache to
speed up general hash table lookups, as well as a fast path in the VM for
the LOAD_ATTR opcode on instance types.  The new configuration options are
MICROPY_OPT_MAP_LOOKUP_CACHE and MICROPY_OPT_LOAD_ATTR_FAST_PATH.  As part
of this improvement the MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE option has
been removed, which provided a similar map caching mechanism but with the
cache stored in the bytecode, which made it not useful on bare metal ports.
The new mechanism is measured to be at least as good as the old one,
applies to more map lookups, has a constant RAM overhead, and applies to
native code as well as bytecode.

These performance options are enabled on the esp32, mimxrt, rp2, stm32 and
unix ports.  For esp32 and mimxrt some code is also moved to RAM to further
boost performance.  On stm32, performance increases by about 20% for
benchmarks that are heavy on name lookups, like misc_pystone.py and
misc_raytrace.py.  On esp32 performance can increase by 2-3x, and on mimxrt
it is up to 6x.

All boards in all ports now have a board.json metadata file, which is used
to automatically build firmware and generate a webpage for that board
(among other possibilities).  Auto-build scripts have been added for this
purpose and they build all esp32, mimxrt, rp2, samd and stm32 boards.  The
generated output is available at https://micropython.org/download.

Support for FROZEN_DIR and FROZEN_MPY_DIR has been deprecated for some time
and was finally removed in this release.  Instead of these, FROZEN_MANIFEST
can be used.  The io.resource_stream() function is also removed, replaced
by the pure Python version in micropython-lib.

The search order for importing frozen Python modules is now controlled by
the ".frozen" entry in sys.path.  This string is added by default in the
second position in sys.path.  User code should adjust sys.path depending on
the desired behaviour.  Putting ".frozen" first in sys.path will speed up
importing frozen modules.

A bug in multiple precision integers with bitwise of -0 was fixed in commit
2c139bbf4e5724ab253b5b034ce925e04267a9c4.

The platform module has been added to allow querying the compiler and
underlying SDK/HAL/libc version.  This is enabled on esp32, mimxrt and
stm32 ports.

The mpremote tool now supports seek, flush, mkdir and rmdir on PC-mounted
filesystems.  And a help command has been added.

The documentation has seen many additions and improvements thanks (for a
second time) to the Google Season of Docs project.  The rp2 documentation
now includes a reference for PIO assembly instructions, a PIO quick
reference and a PIO tutorial.  The random and stm modules have been
documented, along with sys.settrace, manifest.py files and mpremote.  There
is also now more detail about the differences between MicroPython and
standard Python 3.5 and above.

The esp32 port sees support for ESP32-S3 SoCs, and new boards GENERIC_S3,
ESP32_S2_WROVER, LOLIN_S2_MINI, LOLIN_S2_PICO and UM_FEATHERS2NEO.  The PWM
driver has been improved and now supports all PWM timers and channels, and
the duty_u16() and duty_ns() methods, and it keeps the duty constant when
changing frequency.  The machine.bitstream() function has been improved to
use RMT, with an option to select the original bit-banging implementation.

The mimxrt port gained new hardware features: SDRAM and SD card support, as
well as network integration with a LAN driver.  The machine.WDT class was
added along with the machine.reset_cause(), machine.soft_reset(),
machine.unique_id() add machine.bitstream() functions.  DHT sensor support
was added, and f-strings were enabled.

The rp2 port now has support for networking, and bluetooth using NimBLE.
The Nina-W10 WiFi/BT driver is fully integrated and supported by the new
Arduino Nano RP2040 connect board.  I2S protocol support is added along
with a machine.bitstream() driver and DHT sensor support.  The PWM driver
had a bug fix with the accuracy of setting/getting the frequency, and the
duty value is now retained when changing the frequency.

On the samd port there is now support for the internal flash being a block
device, and for filesystems and the os module.  Pin and LED classes have
been implemented.  There are more time functions, more Python features
enabled, and the help() function is added.  SEEED_WIO_TERMINAL and
SEEED_XIAO board definitions are now available.

The stm32 port now has support for F427, F479 and H7A3(Q)/H7B3(Q) MCUs, and
new board definitions for VCC_GND_H743VI, OLIMEX_H407, MIKROE_QUAIL,
GARATRONIC_PYBSTICK26_F411, STM32H73B3I_DK.  A bug was fixed in the SPI
driver where a SPI transfer could fail if the CYW43 WiFi driver was also
active at the same time.

On the windows port the help() function has been enabled, and support for
build variants added, to match the unix port.

The zephyr port upgraded Zephyr to v2.7.0.

The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):

       bare-arm:  -1520  -2.605%
    minimal x86:  -2256  -1.531%
       unix x64:   -457  -0.089%
    unix nanbox:   -925  -0.204%
          stm32:   +312  +0.079% PYBV10
         cc3200:   -176  -0.096%
        esp8266:   +532  +0.076% GENERIC
          esp32: +27096  +1.820% GENERIC
            nrf:   -212  -0.121% pca10040
            rp2:  +9904  +2.051% PICO
           samd: +35332 +33.969% ADAFRUIT_ITSYBITSY_M4_EXPRESS

The changes that dominate these numbers are:
- bare-arm, minimal: use of new MICROPY_CONFIG_ROM_LEVEL_MINIMUM option and
  subsequent disabling of remaining optional features
- unix, cc3200, nrf: general code size reductions of the core
- stm32: performance improvements, addition of platform module
- esp8266: enabling f-strings
- esp32: use of -O2 instead of -Os
- rp2: machine.I2S and other new hardware features
- samd: filesystem support and other new hardware features

Thanks to everyone who contributed to this release: Alan Dragomirecký,
Alexey Shvetsov, Andrew Leech, Andrew Scheller, Antoine Aubert, Boris
Vinogradov, Chris Boudacoff, Chris Fiege, Christian Decker, Damien George,
Daniel Gorny, Dave Hylands, David Michieli, Emilie Feral, Frédéric Pierson,
gibbonsc, Henk Vergonet, iabdalkader, Ihor Nehrutsa, Jan Hrudka, Jan Staal,
jc_.kim, Jim Mussared, Jonathan Hogg, Laurens Valk, leo chung, Lorenzo
Cappelletti, Magnus von Wachenfeldt, Matt Trentini, Matt van de Werken,
Maureen Helm, Michael Bentley, Michael Buesch, Mike Causer, Mike Teachman,
Mike Wadsten, Ned Konz, NitiKaur, oli, patrick, Patrick Van Oosterwijck,
Peter Boin, Peter Hinch, Peter van der Burg, Philipp Ebensberger, Pooya
Moradi, retsyo, robert-hh, roland van straten, Scott Armitage, Sebastian
Wicki, Seon Rozenblum, Sergei Silnov, Simon Baatz, Stewart Bonnick, stijn,
Tobias Thyrrestrup, Tomas Vanek, YoungJoon Chun.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- remove MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
- update Python formatting to latest Black version 21.12b0
- remove support for FROZEN_DIR and FROZEN_MPY_DIR

py core:
- parse: simplify parse nodes representing a list
- emitnative: ensure load_subscr does not clobber existing REG_RET
- mpconfig.h: define initial templates for "feature levels"
- vm: add a fast path for LOAD_ATTR on instance types
- map: add an optional cache of (map+index) to speed up map lookups
- builtinimport: forward all debug printing to MICROPY_DEBUG_PRINTER
- add wrapper macros so hot VM functions can go in fast code location
- runtime: fix crash when exc __new__ doesn't return an exc instance
- mpconfig.h: define the "extra" feature level
- mpconfig.h: revert MICROPY_REPL_INFO to disabled at all levels
- gc: add hook to run code during time consuming GC operations
- showbc: print unary-op string when dumping bytecode
- modsys: replace non-ASCII quote char with ASCII char
- runtime: allow types to use both .attr and .locals_dict
- lexer: support nested [] and {} characters within f-string params
- objfun.h: remove obsolete comments about entries in extra_args
- builtinimport: refactor module importing
- showbc: fix printing of raw bytecode header on nanbox builds
- modio: remove io.resource_stream function
- only search frozen modules when '.frozen' is found in sys.path
- mkrules.cmake: set frozen preprocessor defs early
- runtime: allow initialising sys.path/argv with defaults
- mpstate.h: only include sys.path/argv objects in state when enabled
- mpz: fix bugs with bitwise of -0 by ensuring all 0's are positive
- qstr: reset mpstate.qstr_last_chunk before raising an error
- modbuiltins: add additional macro for extending builtins
- mpconfig.h: define MICROPY_PY_USSL_FINALISER only if not defined

extmod:
- machine_i2c: make SoftI2C configurable via macro option
- machine_spi: make SoftSPI configurable via macro option
- modonewire: make _onewire module configurable via macro option
- machine_pwm: factor out machine.PWM bindings to common code
- move modnetwork and modusocket from stm32 to extmod
- modnetwork: add STA_IF and AP_IF constants
- modnetwork: add extended socket state
- modusocket: add read/write stream methods to socket object
- modnetwork: define network interfaces in port config files
- network_cyw43: make consistent use of STA and AP constants
- modnetwork: remove STM32 references
- modnetwork: remove modnetwork socket u_state member
- mpbthci.h: add mp_bluetooth_hci_uart_any prototype
- nimble: add nimble CMake fragment file
- add platform module
- moduplatform: improve implementation for PC ports
- vfs_posix_file: support MP_STREAM_POLL in vfs_posix_file_ioctl
- modbluetooth: add connection interval to gap_connect
- nimble: update to NimBLE v1.4
- nimble: remove workaround for OS_ENOMEM
- uasyncio: fix gather returning exceptions from a cancelled task
- uplatform: remove unused definitions
- uplatform: use generic custom platform string
- network_ninaw10: fix scan list order to match other NICs
- modbluetooth: support gap_connect(None) to cancel a connection
- modure: redirect regex debug printing to mp_printf
- network_ninaw10: fix config of AP mode
- network_ninaw10: disable active connections before connecting
- network_ninaw10: make NIC state persistent
- network_ninaw10: return -1 on timeout from recv/send
- network_ninaw10: make recv/recvfrom interchangeable
- moduplatform: detect xtensa arch
- modusocket: allow setting timeout on unbound sockets
- modusocket: initialise accepted socket state
- network_ninaw10: use socket timeout preset in modusocket
- modbluetooth: fix conditional compilation of ringbuf_put_uuid
- modbluetooth: put declaration of connect_cancel in correct place

shared:
- libc/string0: don't include string.h, and provide __memcpy_chk
- runtime/pyexec: cleanup EXEC_FLAG flag constants

drivers:
- ninaw10: add ublox Nina-W10 WiFi/BT module driver
- lsm6dsox: add LSM6DSOX driver and examples
- neopixel: avoid heap alloc in fill()
- ninaw10: fix BSSID byte order, and add null byte to ESSID
- ninaw10/nina_wifi_drv: fix DNS resolution

mpy-cross: no changes specific to this component/port

lib:
- mynewt-nimble: switch to the MicroPython fork of NimBLE
- asf4: point submodule to latest commit on circuitpython branch
- update pico-sdk to 1.3.0 and tinyusb to 0.12.0
- stm32lib: update library for L4 v1.17.0, new G4, WL, and MMC fixes
- stm32lib: update library for fix to F7 USB HS

Support components
==================

docs:
- library/os.rst: clarify littlefs requirements for block erase
- library/bluetooth.rst: update incorrect link to gatts_write
- make.bat: change Windows output dir from '_build' to 'build'
- library/machine.I2S.rst: specify that I2S.shift args are kw-only
- esp32: explain ESP32 PWM modes, timers, and channels
- rp2: add reference for PIO assembly instructions, and PIO tutorial
- library/random.rst: document the random module
- reference/mpremote.rst: add docs for mpremote
- reference/manifest.rst: add docs for manifest.py files
- library/stm.rst: document the stm module
- esp32/tutorial: add an example of peripheral control via regs
- rp2/general.rst: fix typo with missing spaces
- library/framebuf.rst: adjust dimensions in example
- library/rp2.rst: update function asm_pio_encode to add sideset_opt
- reference/filesystem.rst: add detail on how to use littlefs fuse
- rp2/quickref.rst: add section on PIO
- library/sys.rst: add docs for sys.settrace
- esp8266/tutorial: fix comments of FrameBuffer examples
- library/uasyncio.rst: detail exception behaviour in cancel/timeout
- library/machine.Timer.rst: document 'id' as positional-only arg
- library/machine.SPI.rst: add example SPI usage
- library/machine.Timer.rst: document `period` and `callback` args
- library/machine.Pin.rst: add Pin.ANALOG mode constant
- remove trailing spaces and convert tabs to spaces
- library/sys.rst: add note about '.frozen' as an entry in sys.path
- differences: document details of new PEPs/features in Python 3.5+
- update copyright year range to include 2022
- esp32: update RMT quickref example to match latest code

examples: no changes specific to this component/port

tests:
- perf_bench: use math.log instead of math.log2
- basics: add tests for type-checking subclassed exc instances
- micropython/const.py: add comment about required config for test
- cpydiff: clarify f-string diffs regarding concatenation
- basics/int_big_cmp.py: add more tests for big-int comparison
- extmod: skip uselect_poll_udp when poll() is not available

tools:
- autobuild: add auto build for GENERIC_C3_USB
- ci.sh: use IDF v4.4 as part of esp32 CI and build GENERIC_S3
- autobuild: add the MIMXRT1010_EVK board to autobuild
- ci.sh: use a specific ESP IDF v4.4 commit
- autobuild: add script to generate website board metadata
- dfu.py: make tool work with python3 when parsing DFU files
- autobuild: automatically build all mimxrt, rp2 and samd boards
- autobuild: automatically build all stm32 boards
- mpremote: implement seek and flush in ioctl method
- autobuild: automatically build all esp32 boards
- upip.py: support == to specify exact package version
- makemanifest.py: make str conversion compatible with Python 2
- makemanifest.py: merge make-frozen.py
- mpremote: add mkdir and rmdir to RemoteFS
- mpremote: add help command
- mpremote: add link to mpremote docs URL in help message
- upip.py: skip '.frozen' entry in sys.path for install path
- autobuild: build esp8266 OTA image with GENERIC_1M board
- ci.sh: upgrade Zephyr docker image to v0.21.0
- ci.sh: build zephyr nucleo_wb55rg to test zephyr bluetooth build

CI:
- workflows: use Python 3.8 for macos workflow
- workflows: add new workflow to build ports download metadata

The ports
=========

all ports:
- add board.json for all boards
- add images, features and urls to board.json
- add '.frozen' as the first entry in sys.path
- move '.frozen' to second entry in sys.path

bare-arm port:
- mpconfigport.h: use MICROPY_CONFIG_ROM_LEVEL_MINIMUM
- mpconfigport.h: disable remaining optional features

cc3200 port: no changes specific to this component/port

esp8266 port:
- boards/GENERIC: enable f-strings
- extract qstr from object when comparing keys in config()
- etshal.h: remove unneeded function declarations
- allow building a board to any dest directory

esp32 port:
- boards: add new FeatherS2-Neo board definition
- machine_timer: use tx_update member for IDF 4.4 and above
- add support for ESP32-S3 SoCs
- boards: add new GENERIC_S3 board definition
- machine_hw_spi: fix hardware SPI DMA channels for S2/S3
- boards: add board definition for ESP32-S2-WROVER module
- boards: add LOLIN_S2_MINI ESP32-S2 board
- machine_pwm: add support for all PWM timers and channels
- README: updated readme with req IDF vers for ESP32-S2, C3 and S3
- usb: add USB host connection detection for CDC serial output
- machine_pin: block out IO16 and IO17 when using SPIRAM on ESP32
- mpthreadport: fix TCB cleanup function so thread_mutex is ready
- main: add option for a board to hook code into startup sequence
- split out WLAN code from modnetwork.c to network_wlan.c
- enable optimisations and move code to iRAM to boost performance
- usb: improve speed of USB CDC output
- add specific deploy_s2.md instructions for esp32-s2
- boards/LOLIN_S2_MINI: add image to board.json
- boards: update board and deploy metadata for UM_xxx boards
- usb: further improve speed of USB CDC output
- boards/LOLIN_S2_PICO: add LOLIN_S2_PICO board definition files
- boards/ESP32_S2_WROVER: link to specific deploy_s2 instructions
- support building with latest IDF v5
- in machine_i2s, send null samples in underflow situations
- in machine_i2s, make object reference arrays root pointers
- add SDCard support for S3, and a GENERIC_S3_SPIRAM board
- boards/GENERIC_S3: enable BLE on ESP32 S3
- machine_pwm: implement duty_u16() and duty_ns() PWM methods
- extract qstr from object when comparing keys in config()
- machine_pin: make GPIO 26 usable for S2,S3 if SPIRAM not config'd
- machine_hw_spi: fix SPI default pins reordering on ESP32-S2/S3
- machine_hw_spi: set proper default SPI(id=1) pins on S2,S3 and C3
- machine_hw_spi: set proper default SPI(id=2) pins on S2 and S3
- boards: remove SPI pin defaults from GENERIC S2/S3 boards
- modnetwork: synchronize WiFi AUTH_xxx constants with IDF values
- machine_pwm: keep duty constant when changing frequency
- machine_bitstream: replace bit-bang code with RMT-based driver
- machine_i2s: add support for ESP-IDF 4.4
- machine_bitstream: fix signal duplication on output pins
- esp32: enable platform module with IDF version
- boards/GENERIC_D2WD: build with -Os optimisation
- esp32_rmt: install RMT driver on core 1
- machine_bitstream: reinstate bitstream bit-bang implementation

javascript port: no changes specific to this component/port

mimxrt port:
- sdcard: implement SDCard driver
- machine_bitstream: add bitstream function to machine module
- rework flash configuration
- sdram: add SDRAM support
- eth: add LAN support and integrate the network module
- modmachine: implement machine.WDT() and machine.reset_cause()
- boards: fix the D14/D15 pin assignment of MIMXRT1050/60/64_EVK
- hal: remove duplicate definitions from flexspi_hyper_flash.h
- dma_channel: fix the DMA channel management
- fix cycle counter for time.ticks_cpu() and machine.bitstream()
- add dht_readinto() to the mimxrt module, and freeze dht.py
- extend the help() message and README.md
- mpconfigport.h: enable f-strings
- modmachine: implement soft_reset() and unique_id() functions
- boards/make-pins.py: allow empty lines and comments in pins.csv
- optimize the runtime speed
- enable the platform module
- boards: add the Seeed ARCH MIX board
- boards: update the board.json files and add deploy_xx.md files
- fix mp_hal_quiet_timing_enter()/exit() so timer still runs
- support PWM using the FLEXPWM and QTMR modules
- define UART 0 on MIMXRT boards
- support selection of PHY type and address
- re-enable eth checksum creation by HW
- fix a tiny unnoticed bug in sdcard.c
- add a driver for the DP83848 PHY device
- refactor the reading of the machine id
- enable ticks_cpu at boot time for NDEBUG builds only
- use -Og instead of -O0 for DEBUG builds
- tidy up the board flash related files
- hal: allow readSampleClkSrc to be configured by a board
- enable MICROPY_PY_USSL_FINALISER

minimal port:
- mpconfigport.h: use MICROPY_CONFIG_ROM_LEVEL_MINIMUM
- Makefile: don't force a 32-bit build
- mpconfigport.h: disable features that are not needed

nrf port:
- Makefile: improve Black Magic Probe commands
- main: use VFS helper function to mount fs and chdir

pic16bit port: no changes specific to this component/port

powerpc port: no changes specific to this component/port

qemu-arm port: no changes specific to this component/port

rp2 port:
- mpconfigport.h: enable heapq module
- add support for bluetooth module using NimBLE
- add framework for networking
- mpconfigport.h: use the "extra" feature level
- enable optimisations (comp goto, map cache, fast attr)
- machine_i2s: add I2S protocol support
- add support for Nina-W10 WiFi/BT module
- boards: add support for Arduino Nano RP2040
- machine_bitstream: implement the machine.bitstream driver
- boards: add neopixel.py to manifest.py
- rp2_pio: support exec with sideset
- boards/PIMORONI_PICOLIPO_16MB: fix 16MB flash size
- boards: add PYBSTICK26 RP2040 board definition
- machine_uart: handle and clear UART RX timeout IRQ
- boards/ARDUINO_NANO_RP2040_CONNECT: set default I2C pins
- machine_pwm: fix PWM frequency setting
- machine_pwm: keep duty value when changing the frequency
- add support for DHT11 and DHT22 sensors
- CMakeLists.txt: allow a board to override PICO_BOARD
- boards/GARATRONIC_PYBSTICK26_RP2040: use correct pico-sdk board cfg

samd port:
- integrate latest asf4, add help, more time funcs and uPy features
- samd_soc: allow a board to configure the low-level MCU config
- add internal flash block device, filesystem and uos support
- add Pin and LED classes, and machine.unique_id
- boards/ADAFRUIT_FEATHER_M0_EXPRESS: update for flash and pins
- boards/ADAFRUIT_ITSYBITSY_M4_EXPRESS: update for flash and pins
- boards/MINISAM_M4: update for flash and pins
- boards/ADAFRUIT_TRINKET_M0: update for flash and pins
- boards/SAMD21_XPLAINED_PRO: update for flash and pins
- boards/SEEED_WIO_TERMINAL: add new board definition
- boards/SEEED_XIAO: add new board definition
- README.md: update README to reflect new features and boards

stm32 port:
- pin: enable GPIO clock of pin if it's constructed without init
- main: don't unconditionally enable GPIO A,B,C,D clocks
- boards/VCC_GND_H743VI: add board definition for VCC_GND_H743VI
- boards/OLIMEX_E407: add Ethernet RMII support
- boards/LEGO_HUB_NO6: remove user paths from cc2564 init file
- boards: remove trailing spaces, and add newline at end of file
- add basic support for STM32H750
- add support for H7A3(Q)/H7B3(Q), and STM32H73B3I_DK board defn
- suggest putting code in main.py not boot.py
- boards/make-pins.py: allow a CPU pin to be hidden
- boards/make-pins.py: allow empty lines and comments in pins.csv
- dma: add functions for external users of DMA to enable clock
- enable LOAD_ATTR fast path, and map lookup caching on >M0
- boards: add OLIMEX H407 board definition
- enable platform module
- extended flash filesystem space to 512K on H743 boards
- boards/NUCLEO_H743ZI: enable VfsLfs2 on NUCLEO_H743ZI(2) boards
- boards: add PF11-BOOT0 to stm32f091_af.csv
- machine_i2c: use hardware I2C for STM32H7
- sdram: enforce gcc opt, and use volatile and DSB in sdram_test
- usbd_cdc_interface: allow a board to hook into USBD CDC RX events
- mpbthciport: allow a board to hook BT HCI poll functions
- pendsv: allow a board to add entries for pendsv_schedule_dispatch
- boards: add images to board.json for Adafruit and VCC_GND boards
- uart: fix race conditions and clearing status in IRQ handler
- mpconfigport.h: use the "extra" feature level
- in machine_i2s, send null samples in underflow situations
- in machine_i2s, make object reference arrays root pointers
- led: support an extra 2 LEDs in board configuration
- boards/MIKROE_CLICKER2_STM32: add more detail to board.json
- boards: add new board MikroElektronika Quail, and F427 support
- main: run optional frozen module at boot
- sdio: don't explicitly disable DMA2 on deinit of SDIO
- dma: make DMA2_Stream3 exclusive to SDIO when CYW43 enabled
- boards: build NUCLEO_WB55 and STM32F769DISC without mboot enabled
- boards: add PYBSTICK26 F411 board definition
- boards/NADHAT_PYBF405: rename board to GARATRONIC_NADHAT_F405
- usb: use a table of allowed values to simplify usb_mode get/set
- boards/NUCLEO_WB55: update rfcore_firmwre for new WS
- flashbdev: support generic flash storage config via link symbols
- boards: convert F413,F439,H743,L4xx,WB55 to new flash FS config
- add support for F479 MCUs
- include HAL MMC code in F4 builds
- boards/make-pins.py: use cpu pins to define static alt-fun macros
- boards/NUCLEO_WB55: fix LED ordering
- boards/LEGO_HUB_NO6: set filesystem label as HUB_NO6
- boards: remove stray '+' characters at start of lines in ld files
- boards: remove unused MICROPY_HW_ENABLE_TIMER config
- boards: enable MICROPY_HW_ENABLE_SERVO on various boards
- update L4 code to build with latest stm32lib and L4 HAL 1.17.0
- main: call sdcard_init when only MICROPY_HW_ENABLE_MMCARD enabled
- sdcard: support 8-bit wide SDIO bus
- sdcard: add config option to force MM card capacity
- factoryreset: init vfs flags before calling pyb_flash_init_vfs
- qspi: fix typo in address comment
- boards/make-pins.py: generate empty ADC table if needed
- boards/OLIMEX_H407: fix typo in OLIMEX H407 board.json
- network_wiznet5k: fix build error with wiznet5k and lwip enabled
- enable MICROPY_PY_USSL_FINALISER

teensy port:
- switch to use manifest.py instead of FROZEN_DIR

unix port:
- enable LOAD_ATTR fast path, and map lookup caching
- modusocket: support MP_STREAM_POLL in unix socket_ioctl
- modos: add support for uos.urandom(n)
- coverage: change remaining printf to mp_printf
- Makefile: use -Og instead of -O0 for debug builds

windows port:
- README: remove unsupported Python instructions for Cygwin
- mpconfigport.h: enable help and help("modules")
- add support for build variants to windows port
- run tests via Makefile
- appveyor: build both standard and dev variants
- appveyor: build mpy-cross only once for mingw-w64
- msvc: run qstr preprocessing phase in parallel

zephyr port:
- mphalport.h: remove unused and unimplemented C-level pin API
- increase minimum CMake version to 3.20.0
- update include path to reboot.h
- get UART console device from devicetree instead of Kconfig
- use CONFIG_USB_DEVICE_STACK for conditional USB device support
- upgrade to Zephyr v2.7.0
- modbluetooth_zephyr: provide dummy connect_cancel function

F-strings, new machine.I2S class, ESP32-C3 support and LEGO_HUB_NO6 board

This release of MicroPython adds support for f-strings (PEP-498), with a
few limitations compared to normal Python.  F-strings are essentially
syntactic sugar for "".format() and make formatting strings a lot more
convenient.  Other improvements to the core runtime include pretty printing
OSError when it has two arguments (an errno code and a string), scheduling
of KeyboardInterrupt on the main thread, and support for a single argument
to the optimised form of StopIteration.

In the machine module a new I2S class has been added, with support for
esp32 and stm32 ports.  This provides a consistent API for transmit and
receive of audio data in blocking, non-blocking and asyncio-based
operation.  Also, the json module has support for the "separators" argument
in the dump and dumps functions, and framebuf now includes a way to blit
between frame buffers of different formats using a palette.  A new,
portable machine.bitstream function is also added which can output a stream
of bits with configurable timing, and is used as the basis for driving
WS2812 LEDs in a common way across ports.

There has been some restructuring of the repository directory layout, with
all third-party code now in the lib/ directory.  And a new top-level
directory shared/ has been added with first-party code that was previously
in lib/ moved there.

The docs have seen further improvement with enhancements and additions to
the rp2 parts, as well as a new quick reference for the zephyr port.
The terms master/slave have been replaced with controller/peripheral,
mainly relating to I2C and SPI usage.  And u-module references have been
replaced with just the module name without the u-prefix to help clear up
the intended usage of modules in MicroPython.

For the esp8266 and esp32 ports, hidden networks are now included in WLAN
scan results.  On the esp32 the RMT class is enhanced with idle_level and
write_pulses modes.  There is initial support for ESP32-C3 chips with
GENERIC_C3 and GENERIC_C3_USB boards.

The javascript port has had its Makefile and garbage collector
implementation reworked so it compiles and runs with latest the Emscripten
using asyncify.

The mimxrt port sees the addition of hardware I2C and SPI support, as well
as some additional methods to the machine module.  There is also support
for Hyperflash chips.

The nrf port now has full VFS storage support, enables source-line on
traceback, and has .mpy features consistent with other ports.

For the rp2 port there is now more configurability for boards, and more
boards added.

The stm32 port has a new LEGO_HUB_NO6 board definition with detailed
information how to get this LEGO Hub running stock MicroPython.  There is
also now support to change the CPU frequency on STM32WB MCUs.  And USBD_xxx
descriptor options have been renamed to MICROPY_HW_USB_xxx.

Thanks to everyone who contributed to this release: Amir Gonnen, Andrew
Scheller, Bryan Tong Minh, Chris Wilson, Damien George, Daniel Mizyrycki,
David Lechner, David P, Fernando, finefoot, Frank Pilhofer, Glenn Ruben
Bakke, iabdalkader, Jeff Epler, Jim Mussared, Jonathan Hogg, Josh Klar,
Josh Lloyd, Julia Hathaway, Krzysztof Adamski, Matúš Olekšák, Michael
Weiss, Michel Bouwmans, Mike Causer, Mike Teachman, Ned Konz, NitiKaur,
oclyke, Patrick Van Oosterwijck, Peter Hinch, Peter Züger, Philipp
Ebensberger, robert-hh, Roberto Colistete Jr, Sashkoiv, Seon Rozenblum,
Tobias Thyrrestrup, Tom McDermott, Will Sowerbutts, Yonatan Goldschmidt.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- fix signed shifts and NULL access errors from -fsanitize=undefined
- update to point to files in new shared/ directory

py core:
- mpstate: make exceptions thread-local
- mpstate: schedule KeyboardInterrupt on main thread
- mperrno: add MP_ECANCELED error code
- makeqstrdefs.py: don't include .h files explicitly in preprocessing
- mark unused arguments from bytecode decoding macros
- objexcept: pretty print OSError also when it has 2 arguments
- makeversionhdr: add --tags arg to git describe
- vm: simplify handling of MP_OBJ_STOP_ITERATION in yield-from opcode
- objexcept: make mp_obj_exception_get_value support subclassed excs
- support single argument to optimised MP_OBJ_STOP_ITERATION
- introduce and use mp_raise_type_arg helper
- modsys: optimise sys.exit for code size by using exception helpers
- objexcept: make mp_obj_new_exception_arg1 inline
- obj: fix formatting of comment for mp_obj_is_integer
- emitnative: reuse need_reg_all func in need_stack_settled
- emitnative: ensure stack settling is safe mid-branch
- runtime: fix bool unary op for subclasses of native types
- builtinimport: fix condition for including do_execute_raw_code()
- mkrules: automatically build mpy-cross if it doesn't exist
- implement partial PEP-498 (f-string) support
- lexer: clear fstring_args vstr on lexer free
- mkrules.mk: do submodule sync in "make submodules"

extmod:
- btstack: add missing call to mp_bluetooth_hci_uart_deinit
- btstack: check that BLE is active before performing operations
- uasyncio: get addr and bind server socket before creating task
- axtls-include: add axtls_os_port.h to customise axTLS
- update for move of crypto-algorithms, re1.5, uzlib to lib
- moduselect: conditionally compile select()
- nimble: fix leak in l2cap_send if send-while-stalled
- btstack/btstack.mk: use -Wno-implicit-fallthrough, not =0
- utime: always invoke mp_hal_delay_ms when >= to 0ms
- modbluetooth: clamp MTU values to 32->UINT16_MAX
- nimble: allow modbluetooth binding to hook "sent HCI packet"
- nimble: add "memory stalling" mechanism for l2cap_send
- uasyncio: in open_connection use address info in socket creation
- modujson: add support for dump/dumps separators keyword-argument
- modlwip: fix close and clean up of UDP and raw sockets
- modbluetooth: add send_update arg to gatts_write
- add machine.bitstream
- modframebuf: enable blit between different formats via a palette

lib:
- tinyusb: update to version 0.10.1
- pico-sdk: update to version 1.2.0
- utils/stdout_helpers: make mp_hal_stdout_tx_strn_cooked efficient
- axtls: switch to repo at micropython/axtls
- axtls: update to latest axtls 2.1.5 wih additional commits
- re1.5: move re1.5 code from extmod to lib
- uzlib: move uzlib code from extmod to lib
- crypto-algorithms: move crypto-algorithms code from extmod to lib
- update README's based on contents of these dirs

drivers:
- neopixel: add common machine.bitstream-based neopixel module
- neopixel: optimize fill() for speed
- neopixel: reduce code size of driver
- cyw43: fix cyw43_deinit so it can be called many times in a row
- cyw43: make wifi join fail if interface is not active

mpy-cross:
- disable stack check when building with Emscripten

Support components
==================

docs:
- library: document new esp32.RMT features and fix wait_done
- library: warn that ustruct doesn't handle spaces in format strings
- esp8266/tutorial: change flash mode from dio to dout
- replace master/slave with controller/peripheral in I2C and SPI
- rp2: enhance quickref and change image to Pico pinout
- rp2: update general section to give a brief technical overview
- library/utime.rst: clarify behaviour and precision of sleep ms/us
- library/uasyncio.rst: document stream readexactly() method
- library/machine.I2S.rst: fix use of sd pin in examples
- zephyr: add quick reference for the Zephyr port
- library/zephyr: add libraries specific to the Zephyr port
- templates: add unix and zephyr quickref links to top-index
- rename ufoo.rst to foo.rst
- replace ufoo with foo in all docs
- library/index.rst: clarify module naming and purpose
- library/builtins.rst: add module title
- library/network.rst: simplify socket import
- add docs for machine.bitstream and neopixel module
- library: fix usage of :term: for frozen module reference
- esp8266: use monospace for software tools
- reference: mention that slicing a memoryview causes allocation

examples: no changes specific to this component/port

tests:
- extmod: make uasyncio_heaplock test more deterministic
- cpydiff/modules_struct_whitespace_in_format: run black
- extmod/ujson: add tests for dump/dumps separators argument
- run-multitests.py: add broadcast and wait facility
- multi_bluetooth/ble_subscribe.py: add test for subscription
- extmod/vfs_fat_finaliser.py: ensure alloc at never-used GC blocks
- basics: split f-string debug printing to separate file with .exp
- pybnative: make while.py test run on boards without pyb.delay

tools:
- autobuild: add scripts to build release firmware
- remove obsolete build-stm-latest.sh script
- ci.sh: run apt-get update in ci_powerpc_setup
- makemanifest.py: allow passing flags to mpy-tool.py
- autobuild: add mimxrt port to build scripts for nightly builds
- pyboard.py: add cmd-line option to make soft reset configurable
- mpremote: swap order of PID and VID in connect-list output
- ci.sh: build unix dev variant as part of macOS CI
- ci.sh: build GENERIC_C3 board as part of esp32 CI
- autobuild: use separate IDF version to build newer esp32 SoCs
- autobuild: add FeatherS2 and TinyS2 to esp32 auto builds
- mpremote: add seek whence for mounted files
- mpremote: raise OSError on unsupported RemoteFile.seek
- autobuild: add the MIMXRT1050_EVKB board to the daily builds
- ci.sh: add mpy-cross build to nrf port
- codeformat.py: include ports/nrf/modules/nrf in code formatting
- gen-cpydiff.py: don't rename foo to ufoo in diff output
- autobuild: add auto build for Silicognition wESP32
- mpremote: fix connect-list in case VID/PID are None
- mpremote: add "devs" shortcut for "connect list"
- mpremote: remove support for pyb.USB_VCP in/out specialisation
- autobuild: don't use "-B" for make, it's already a fresh build
- pyboard.py: move --no-exclusive/--soft-reset out of mutex group
- pyboard.py: make --no-follow use same variable as --follow
- pyboard.py: add --exclusive to match --no-exclusive
- pyboard.py: make --no-soft-reset consistent with other args
- uncrustify: force 1 newline at end of file
- mpremote: bump version to 0.0.6

CI:
- workflows: add workflow to build and test javascript port
- workflows: switch from Coveralls to Codecov
- workflows: switch from lcov to gcov
- workflows: add workflow to build and test unix dev variant

The ports
=========

all ports:
- use common mp_hal_stdout_tx_strn_cooked instead of custom one
- update for move of crypto-algorithms, uzlib to lib
- rename USBD_VID/PID config macros to MICROPY_HW_USB_VID/PID

bare-arm port: no changes specific to this component/port

cc3200 port: no changes specific to this component/port

esp8266 port:
- add __len__ to NeoPixel driver to support iterating
- Makefile: add more libm files to build
- include hidden networks in WLAN.scan results
- replace esp.neopixel with machine.bitstream
- remove dead code for end_ticks in machine_bitstream

esp32 port:
- boards/sdkconfig.base: disable MEMPROT_FEATURE to alloc from IRAM
- add __len__ to NeoPixel driver to support iterating
- main: allow MICROPY_DIR to be overridden
- esp32_rmt: fix RMT looping in newer IDF versions
- esp32_rmt: enhance RMT with idle_level and write_pulses modes
- add new machine.I2S class for I2S protocol support
- machine_spi: calculate actual attained baudrate
- machine_hw_spi: use a 2 item SPI queue for long transfers
- machine_dac: add MICROPY_PY_MACHINE_DAC option, enable by default
- machine_i2s: add MICROPY_PY_MACHINE_I2S option, enable by default
- fix use of mp_int_t, size_t and uintptr_t
- add initial support for ESP32C3 SoCs
- boards/GENERIC_C3: add generic C3-based board
- modmachine: release the GIL in machine.idle()
- mphalport: always yield at least once in delay_ms
- machine_uart: add flow kw-arg to enable hardware flow control
- boards: add Silicognition wESP32 board configuration
- mpconfigport.h: enable reverse and inplace special methods
- include hidden networks in WLAN.scan results
- makeimg.py: get bootloader and partition offset from sdkconfig
- enable MICROPY_PY_FSTRINGS by default
- machine_hw_spi: release GIL during transfers
- machine_pin: make check for non-output pins respect chip variant
- replace esp.neopixel with machine.bitstream
- remove dead code for end_ticks in machine_bitstream
- boards: add GENERIC_C3_USB board with USB serial/JTAG support

javascript port:
- rework Makefile and GC so it works with latest Emscripten
- Makefile: suppress compiler errors from array bounds
- Makefile: change variable to EXPORTED_RUNTIME_METHODS

mimxrt port:
- move calc_weekday helper function to timeutils
- machine_spi: add the SPI class to the machine module
- moduos: seed the PRNG on boot using the TRNG
- boards: set vfs partition start to 1 MBbyte
- main: skip running main.py if boot.py failed
- main: extend the information returned by help()
- mimxrt_flash: remove commented-out code
- modmachine: add a few minor methods to the machine module
- machine_led: use mp_raise_msg_varg helper
- machine_i2c: add hardware-based machine.I2C to machine module
- add support for Hyperflash chips
- boards: add support for the MIMXRT1050_EVKB board
- machine_pin: implement ioctl for Pin

minimal port:
- Makefile: add support for building with user C modules

nrf port:
- modules: replace master/slave with controller/peripheral in SPI
- boards/common.ld: calculate unused flash region
- modules/nrf: add new nrf module with flash block device
- drivers: add support for using flash block device with SoftDevice
- mpconfigport.h: expose nrf module when MICROPY_PY_NRF is set
- README: update README.md to reflect internal file systems
- mpconfigport.h: tune FAT FS configuration
- Makefile: add _fs_size linker script override from make
- modules/uos: allow a board to configure MICROPY_VFS_FAT/LFS1/LFS2
- mpconfigport.h: enable MICROPY_PY_IO_FILEIO when an FS is enabled
- qstrdefsport.h: add entries for in-built FS mount points
- main: add auto mount and auto format hook for internal flash FS
- boards: enable needed features for FAT/LFS1/LFS2
- facilitate use of freeze manifest
- boards: set FROZEN_MANIFEST blank when SD present on nrf51 targets
- modules/scripts: add file system formatting script
- Makefile: set default manifest file for all targets
- mphalport: add dummy function for mp_hal_time_ns()
- boards: enable MICROPY_VFS_LFS2 for all target boards
- modules/uos: add ilistdir to uos module
- modules/nrf: add function to enable/disable DCDC
- enable source line on tracebacks
- set .mpy features consistent with documentation and other ports

pic16bit port: no changes specific to this component/port

powerpc port: no changes specific to this component/port

qemu-arm port: no changes specific to this component/port

rp2 port:
- use 0=Monday datetime convention in RTC
- machine_rtc: in RTC.datetime, compute weekday automatically
- CMakeLists.txt: suppress compiler errors for pico-sdk and tinyusb
- tusb_config.h: set CFG_TUD_CDC_EP_BUFSIZE to 256
- machine_uart: add hardware flow control support
- machine_uart: allow overriding default machine UART pins
- machine_i2c: allow boards to configure I2C pins using new macros
- machine_spi: allow boards to configure SPI pins using new macros
- machine_uart: fix poll ioctl to also check hardware FIFO
- machine_uart: fix read when FIFO has chars but ringbuf doesn't
- tusb_port: allow boards to configure USB VID and PID
- boards/ADAFRUIT_FEATHER_RP2040: configure custom VID/PID
- boards/ADAFRUIT_FEATHER_RP2040: configure I2C/SPI default pins
- boards/SPARKFUN_PROMICRO: configure UART/I2C/SPI default pins
- boards/SPARKFUN_THINGPLUS: configure I2C/SPI default pins
- boards: add Adafruit ItsyBitsy RP2040
- boards: add Adafruit QT Py RP2040
- boards: add Pimoroni Pico LiPo 4MB
- boards: add Pimoroni Pico LiPo 16MB
- boards: add Pimoroni Tiny 2040
- CMakeLists.txt: allow a board's cmake to set the manifest path
- enable MICROPY_PY_FSTRINGS by default
- Makefile: add "submodules" target, to match other ports
- rp2_flash: disable IRQs while calling flash_erase/program
- CMakeLists.txt: add option to enable double tap reset to bootrom
- mpconfigport.h: allow boards to add root pointers

samd port:
- add support for building with user C modules

stm32 port:
- softtimer: add soft_timer_reinsert() helper function
- mpbthciport: change from systick to soft-timer for BT scheduling
- provide a custom BTstack runloop that integrates with soft timer
- usb: make irq's default trigger enable all events
- boardctrl: skip running main.py if boot.py had an error
- sdio: fix undefined reference to DMA stream on H7
- dma: add DMAMUX configuration for H7 to fix dma_nohal_init
- main: call mp_deinit() at end of main
- adc: allow using ADC12 and ADC3 for H7
- adc: define the ADC instance used for internal channels
- adc: simplify and generalise how pin_adcX table is defined
- add new machine.I2S class for I2S protocol support
- boards/NUCLEO_F446RE: fix I2C1 pin assignment to match datasheet
- replace master/slave with controller/peripheral in I2C and SPI
- systick: always POLL_HOOK when delaying for milliseconds
- sdram: make SDRAM test cache aware, and optional failure with msg
- boards/NUCLEO_F446RE: enable CAN bus support
- boards: add support for SparkFun STM32 MicroMod Processor board
- uart: fix LPUART1 baudrate set/get
- uart: support low baudrates on LPUART1
- boards/STM32F429DISC: set correct UART2 pins and add UART3/6
- boards/NUCLEO_F439ZI: add board definition for NUCLEO_F439ZI
- boards/LEGO_HUB_NO6: add board definition for LEGO_HUB_NO6
- Makefile: update to only pull in used Bluetooth library
- README.md: update supported MCUs, and submodule and mboot use
- usbd_desc: rename USBD_xxx descriptor opts to MICROPY_HW_USB_xxx
- usbd_cdc_interface: rename USBD_CDC_xx opts to MICROPY_HW_USB_xx
- powerctrl: support changing frequency on WB MCUs
- boards/NUCLEO_H743ZI2: add modified version of NUCLEO_H743ZI
- mbedtls: fix compile warning about uninitialized val
- enable MICROPY_PY_FSTRINGS by default
- add implementation of machine.bitstream
- Makefile: allow GIT_SUBMODULES and LIBS to be extended
- stm32_it: support TIM17 IRQs on WB MCUs
- disable computed goto on constrained boards
- storage: make extended-block-device more configurable
- boards/LEGO_HUB_NO6: change SPI flash storage to use hardware SPI
- boards/LEGO_HUB_NO6: skip first 1MiB of SPI flash for storage
- boards/LEGO_HUB_NO6: add make commands to backup/restore firmware

teensy port: no changes specific to this component/port

unix port:
- modffi: add option to lock GC in callback, and cfun access
- Makefile: add back LIB_SRC_C to list of object files
- variants: enable help and help("modules") on standard and dev
- Makefile: disable error compression on arm-linux-gnueabi-gcc

windows port:
- Makefile: add .exe extension to executables name
- appveyor: update to VS 2017 and use Python 3.8 for build/test

zephyr port:
- machine_spi: add support for hardware SPI

New mpremote tool, and the mimxrt port gets Pin, ADC, UART, RTC and VFS

This release of MicroPython includes a new command-line tool called
"mpremote", which is intended to be the main way to remotely control a
MicroPython-based device from the command line.  It features a serial
terminal, filesystem access, support to mount a local directory on the
remote device, and a macro language to define custom commands.  This tool
can be installed from PyPI via "pip3 install mpremote", and it works on
Linux, Windows and Mac.  As part of this, improvements were made to
pyboard.py including opening serial ports in exclusive mode to more easily
manage multiple devices.

In the Python core, OSError exceptions now support the ".errno" attribute,
and an option was added to compile MicroPython without error messages to
further reduce code size where needed.  The REPL was improved so that it
does not tab-complete private methods (those starting with underscore, if
no underscore has been typed yet), and it also now tab completes built-in
module names after "import" is typed.

There has been a minor breaking change to a relative import exception: what
was previously a ValueError was changed to ImportError, following the same
change in CPython.  See commit 53519e322a5a0bb395676cdaa132f5e82de22909.

In the extmod components, uctypes has a fix for the size and offset
calculation for ARRAY of FLOAT32, uhashlib now raises an exception if a
hash is reused after digest is called, and urandom supports passing 0 to
getrandbits (following the CPython change).  In uasyncio, the readinto
method is added to the Stream class, and two race conditions were fixed:
one with start_server and wait_closed, and the other with cancelling a
task waiting on finished task; see de2e081260395f47d21bf39a97f3461df3d8b94f
and 514bf1a1911ac9173a00820b7e09dfb387e6b941 respectively.

The esp32 port now supports specifying FROZEN_MANIFEST with new CMake build
system, has NeoPixel support on GPIO32 and GPIO33, network.LAN support in
IDF v4.1 and above, and a new "reconnects" option in the WLAN STA interface
to configure how many (if any) reconnection attempts are made if the WiFi
goes down.

Many features have been added to the mimxrt port, including: VFS filesystem
support with internal flash storage, Pin, Pin.irq and ADC support, UART,
SoftI2C and SoftSPI bus support, Timer and RTC classes, and floating point
numbers.

The rp2 port now has the machine.RTC class to configure the RTC, as well as
new board definition files for SparkFun's Thing Plus RP2040 and Pro Micro
boards.

The stm32 port now supports static soft timers with a C-based callback, and
mboot has been made more configurable, in particular the LEDs and reset
mode selection can now be fully customised by a board.  Two new boards have
been added: VCC_GND_F407VE and VCC_GND_F407ZG.  A bug fix was made to the
SDIO driver to make sure DMA doesn't turn off mid-transfer; this affected
WLAN operation when certain SPI buses were being used.  See commit
a96afae90f6e5d693173382561d06e583b0b5fa5 for details.  Pin configuration of
UART has been modified so pull-up is now configured only on RX and CTS, not
TX and RTS; see 748339b28126e69fd2dc2778b2a182901d0a4693.  The USB_VCP
class has a new irq method to set a callback on USB data RX events.  The
Ethernet driver now supports low-power mode, and has a fix so the link
status is reported correctly.

On the zephyr port, scheduled callbacks are now run at idle REPL and during
sleeps, and there is an initial ubluetooth module which supports BLE
scanning and advertising.  Configuration is provided for the nucleo_wb55rg
board.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Thanks to everyone who contributed to this release!

Main components
===============

all:
- rename mp_keyboard_interrupt to mp_sched_keyboard_interrupt
- replace busses with buses

py core:
- objexcept: support errno attribute on OSError exceptions
- add option to compile without any error messages at all
- dynruntime.h: add mp_obj_get_array() function
- profile: use mp_handle_pending() to raise pending exception
- scheduler: add mp_sched_exception() to schedule a pending exception
- scheduler: add optional port hook for when something is scheduled
- runtime: remove commented-out code from mp_deinit()
- scheduler: add missing MICROPY_WRAP_MP_SCHED_EXCEPTION usage
- repl: filter private methods from tab completion
- repl: enter four spaces when there are no matches
- repl: refactor autocomplete to reduce nesting
- repl: refactor autocomplete, extracting reusable parts
- repl: autocomplete builtin modules
- gc: make gc_lock_depth have a count per thread
- mkenv.mk: don't emit info about BUILD_VERBOSE if it's set
- objarray: prohibit comparison of mismatching types
- objarray: implement more/less comparisons for array
- objarray: use mp_obj_memoryview_init helper in mp_obj_new_memoryview
- objarray: fix constructing a memoryview from a memoryview
- nlraarch64: add underscore prefix to function symbols for Darwin ABI
- nlrx64: correct the detection of Darwin ABI
- asmx64: support use of top 8 regs in src_r64 argument
- emitnative: fix x86-64 emitter to generate correct 8/16-bit stores
- mkrules.cmake: add MPY_LIB_DIR and BOARD_DIR to makemanifest call
- asmarm: use builtin func to flush I- and D-cache on ARM 7 archs
- compile: raise an error on async with/for outside an async function
- gc: access the list of root pointers in an asan-compatible way
- repl: don't read past the end of import_str
- builtinimport: change relative import's ValueError to ImportError
- emitglue: always flush caches when assigning native ARM code
- stackctrl: prevent unused-var warning when stack checking disabled
- gc: only use no_sanitize_address attribute for GCC 4.8 and above

extmod:
- uasyncio: use .errno instead of .args[0] for OSError exceptions
- remove old comments used for auto-doc generation
- moductypes: remove double blank lines and debugging printf's
- moductypes: replace numbers with macro constants
- moductypes: fix size and offset calculation for ARRAY of FLOAT32
- moduhashlib: put hash obj in final state after digest is called
- modurandom: add error message when getrandbits has bad value
- modurandom: support an argument of bits=0 to getrandbits
- uasyncio: fix start_server and wait_closed race condition
- uasyncio: add readinto() method to Stream class
- uasyncio: fix race with cancelled task waiting on finished task
- nimble: remove TODO comment about notify_custom freeing om

lib:
- utils: remove unused PYEXEC_SWITCH_MODE from pyexec.h
- utils: add ARM semihosting utility functions
- lwip: switch to use GitHub mirror repo
- mbedtls: switch to currently latest commit of LTS branch v2.16

drivers:
- sdcard: add sleep_ms(1) delay in SDCard.readinto sync loop
- cyw43/cyw43_ctrl: use new sdio enable API functions
- cyw43/cywbt: add compile option for RF switch
- cyw43/cywbt: remove hard-coded UART6 alternate function setting
- display/ssd1306.py: add rotate method
- display/ssd1306.py: add support for 72x40 displays

mpy-cross: no changes specific to this component/port

Support components
==================

docs:
- library/machine: specify initial machine.PWM class
- library/machine: add machine.bootloader docs
- esp8266: add note about simultaneous use of STA_IF and AP_IF
- esp8266: add instructions on entering programming mode manually
- esp8266: clarify limitations of SSL in esp8266 and fix typos
- fix some spelling mistakes
- pyboard: fix typo in pyb.Switch tutorial
- esp32: add UART to quickref
- esp32: add WDT to quickref
- esp32: add SDCard to quickref
- esp8266: add WDT to quickref
- library: add initial API reference for rp2 module and its classes
- library/rp2.rst: fix typo overriden->overridden
- esp32: add APA106 to quickref
- esp32: mention Signal in GPIO section of quickref
- esp8266: mention Signal in GPIO section of quickref
- esp8266: add SSD1306 to quickref and tutorial
- library: clarify what type of algorithm is implemented in heapq
- library: add a blank line to fix formatting for ussl docs
- library/pyb.Pin.rst: update the arguments for Pin.init()
- rp2: add skeleton docs for the rp2 port
- library/machine.RTC.rst: document datetime method and fix ex code
- esp32: document WLAN "reconnects" config option

examples: no changes specific to this component/port

tests:
- use .errno instead of .args[0] for OSError exceptions
- run-multitests.py: provide some convenient serial device shorcuts
- multi_bluetooth: add performance test for gatt char writes
- thread: make stress_create.py test run on esp32
- thread: make stress_aes.py test run on bare-metal ports
- thread: make exc1,exit1,exit2,stacksize1,start1 tests run on rp2
- run-perfbench.py: fix native feature check
- run-multitests.py: flush stdout for each line of trace output
- run-tests.py: parallelize running tests by default
- cpydiff: add test and workaround for function.__module__ attr
- make float and framebuf tests skip or run on big-endian archs
- extmod/btree_gc.py: close the database to avoid a memory leak
- basics: split out literal tests that raise SyntaxWarning on CPy
- run-multitests.py: allow to work without sys.stdout on target
- multi_bluetooth/ble_gap_advertise.py: allow to work without set
- unix: add ffi test for integer types
- cpydiff: add test for array constructor with overflowing value
- float: make bytes/bytearray construct tests work with obj repr C

tools:
- metrics.py: add rp2 port to table of ports that can be built
- upip.py: use .errno instead of .args[0] for OSError exceptions
- pyboard.py: support opening serial port in exclusive mode
- gen-cpydiff.py: fix formatting of doc strings for new Black
- makemanifest.py: show directory name if there is a FreezeError
- mpy_ld.py: support R_X86_64_GOTPCREL reloc for x86-64 arch
- pydfu.py: remove default VID/PID values
- ci.sh: update zephyr docker image to v0.17.3
- ci.sh: use FROZEN_MANIFEST in an esp32 build to test feature
- mpy-tool.py: support relocating ARMv6 arch
- tinytest-codegen.py: add command-line option to exclude tests
- ci.sh: build Cortex-A9 sabrelite board as part of qemu-arm CI
- pyboard.py: track raw REPL state via in_raw_repl variable
- pyboard.py: add "soft_reset" option to Pyboard.enter_raw_repl()
- mpremote: add new CLI utility to interact with remote device
- ci.sh: build mpy-cross as part of ci_mimxrt_build
- mpremote: use available ports instead of auto-connect list
- mpremote: use signal to capture and handle ctrl-C on Windows

CI:
- workflows: add CI workflow for mimxrt port
- workflows: add workflow to build and run unix port on MIPS
- workflows: add workflow to build and run unix port on ARM

The ports
=========

bare-arm port:
- switch to use MICROPY_ERROR_REPORTING_NONE to reduce size

cc3200 port: no changes specific to this component/port

esp8266 port:
- modnetwork: use mp_handle_pending() to raise pending exception
- boards/GENERIC_512K: add custom manifest without FS modules
- update manifest to point to new dirs in micropython-lib
- boards/GENERIC_512K: add custom minimal _boot.py

esp32 port:
- CMakeLists.txt: require CMake version 3.12
- restore FROZEN_MANIFEST support with new CMake build system
- esp32_rmt: clear config struct before filling it out
- mpthreadport: don't explicitly free thread struct in TCB cleanup
- mpthreadport: use binary semaphore instead of mutex
- extend support for S2 series, and S3 where applicable
- boards: rename TINYPICO board to UM_TINYPICO
- boards: add UM_FEATHERS2 and UM_TINYS2 board definitions
- boards/UM_TINYPICO: fix include of sdkconfig fragment
- machine_i2c: allow boards to configure I2C pins using new macros
- boards: set default I2C and SPI pins on UM_xxx boards
- boards: fix spelling mistakes in comments for UM_xxx boards
- update manifest to point to new dirs in micropython-lib
- boards: add M5STACK_ATOM board definition
- espneopixel: add support for GPIO32 and GPIO33
- Makefile: fix wrong target for partition-table.bin
- makeimg.py: load sizes from partition table and verify data fits
- partitions-2MiB.csv: update table so firmware fits
- README: describe how to select compatible version of existing IDF
- network_lan: add Ethernet support for IDF v4.1 and above
- modnetwork: add "reconnects" option to WLAN STA interface
- machine_hw_spi: allow None for unused pins in initializer
- machine_sdcard: use deinit_p to deinit SD bus in SPI mode

javascript port: no changes specific to this component/port

mimxrt port:
- improve ticks and sleep functions using GPT
- implement machine.Pin class
- enable built-in help
- extend the Pin module for SoftI2C, SoftSPI support
- add custom help text and enable help("modules")
- enable frozen modules
- add flash storage support with VFS and littlefs filesystem
- boards/TEENSY40: re-create the flash FS after deploy
- add the Timer class to the machine module
- remove __WFE() from MICROPY_EVENT_POLL_HOOK
- machine_timer: reuse any existing timer objects
- machine_timer: leave the Timer clock source at IPG clock
- machine_rtc: add the RTC class to the machine module
- add floating point support
- enable many Python and some extmod features
- machine_adc: add the ADC class to the machine module
- boards: add board configuration files for Teensy 4.1
- machine_rtc: change RTC.datetime() tuple to match other ports
- machine_rtc: maintain microsecond offset
- machine_uart: add the UART class to the machine module
- machine_pin: implement pin.irq() functionality
- modutime: extend the time module

minimal port: no changes specific to this component/port

nrf port:
- boards/microbit: use mp_sched_exception() where appropriate
- add machine.memXX, and allow boards to customise some features
- boards: add support for evk_nina_b3 board
- add more math sources to Makefile, and enable log2 implementation

pic16bit port:
- Makefile: make the XC compiler version user-configurable

powerpc port: no changes specific to this component/port

qemu-arm port:
- add support for Cortex-A9 via sabrelite board

rp2 port:
- boards: add board definition for SparkFun Thing Plus RP2040
- boards: add board definition for SparkFun Pro Micro board
- tusb_port: add the device unique-id to the USB id
- move manifest.py to boards directory
- mpthreadport: add mp_thread_deinit to reset core1 on soft reset
- CMakeLists.txt: include tinyusb_common in PICO_SDK_COMPONENTS
- machine_rtc: add initial support for RTC
- machine_rtc: check return value from rtc_set_datetime

samd port: no changes specific to this component/port

stm32 port:
- boards/pllvalues.py: support wider range of PLL values for F413
- machine_timer: improve usability of Timer constructor and init
- mboot: allow unpacking dfu without secret key
- correct typos in project README files
- uart: fix H7 UART clock source configuration
- softtimer: add support for having a C-based callback
- softtimer: support static soft timer instances
- boardctrl: add constants for reset mode values
- boardctrl: show first reset-mode state on LEDs when selecting
- mboot: allow a board to add source files to the build
- adc: allow mboot to use basic ADC functions
- mboot: fix mp_hal_delay_us() and add mp_hal_ticks_ms()
- mboot: allow a board to customise the linker scripts
- mboot: allow mboot to be placed at any location in flash
- sdcard: allow configuring the SDMMC periph used for SD/MMC card
- uart: enable HW flow control for UART 1/5/7/8
- sdio: add functions to re/enable SDIO/SDIOIT
- boards/PYBD_SF2: enable RF switch compile option
- sdio: allow configuring the SDMMC periph used for SDIO
- boards: change default LSI_VALUE to 32000 for F4 MCUs
- powerctrl: add MICROPY_HW_ENTER_BOOTLOADER_VIA_RESET option
- boardctrl: adjust logic for running boot.py, main.py
- mboot: add MBOOT_LEAVE_BOOTLOADER_VIA_RESET option
- mboot: make LEDs and reset-mode selection more configurable
- boards: add VCC_GND_F407VE board
- boards: add VCC_GND_F407ZG board
- sdio: fix case of SDIO DMA turning off mid transfer
- uart: configure pull-up only on RX and CTS, not TX and RTS
- mboot: leave bootloader from thread mode, not from IRQ
- boards/NUCLEO_L432KC: fix FS size and enable LFS1 filesystem
- boards/PYBD_SF2: disable GCC 11 warnings for array bounds
- usb: add USB_VCP.irq method, to set a callback on USB data RX
- boards: enable MICROPY_HW_SPIFLASH_ENABLE_CACHE on VCC_GND boards
- sdram: prevent array-bounds warnings with GCC 11
- eth: add low-power mode configuration option
- eth: fix eth_link_status function to use correct BSR bit

teensy port:
- provide own implementation of gc_collect, to not use stm32
- correct typos in project README files

unix port:
- modffi: use a union for passing/returning FFI values
- main: increase stack limit on ARM architectures
- modffi: fix conversion between Python integers and ffi types
- fix build on arm64-darwin due to integer cast

windows port:
- mpconfigport.h: enable features also present in unix port

zephyr port:
- run scheduled callbacks at REPL and during mp_hal_delay_ms
- modmachine: add machine.idle()
- boards: add config for nucleo_wb55rg board
- update disk access configuration for Zephyr v2.6.0
- disable CONFIG_NET_SOCKETS_POSIX_NAMES
- update to Zephyr v2.6.0
- add initial ubluetooth module integration
- boards: enable ubluetooth on nucleo_wb55rg board

The esp32 port moves to CMake and has S2 support, new features for rp2

This release of MicroPython adds general support in the core for using
CMake as a build system.  The rp2 port is consolidated to use the new
CMake files, and the esp32 and zephyr ports have switched to build as
pure CMake projects.  These three ports have SDKs which are built around
CMake and this change should make them easier to maintain and use.

As part of this work, CMake based ports now have support for user C
modules. Authors of user C modules should now provide both .mk and .cmake
configuration files (following the documentation and examples).

A bug was fixed in the multiple precision integer library, an arithmetic
overflow in the long division routine.  Prior to this fix certain integer
divisions would take excessive time and produce incorrect results.  See
commit 0a59938574502b19b3d685133084399c090d3c11 for details.  There was
also a fix for regular expressions, to check and report byte overflow
errors when compiling expressions.  See commit
172fb5230a3943eeb6fbbb4de1dc56b16e2a7637.

In the uasyncio library, a new MicroPython extension has been added,
ThreadSafeFlag, which can be set from outside the asyncio event loop,
such as other threads, IRQs or scheduler context.  It allows preemptive
code like IRQs to signal asyncio tasks, which are by nature cooperative
(non-preemptive).  asyncio.current_task() has also been added, with the
same semantics as CPython.

As mentioned above, the esp32 port has switched to a full CMake-based
project, and traditional make capability has been removed (although a
simple helper Makefile remains to keep top-level build/deploy commands
consistent with other ports).  Because of the move to CMake, network.LAN
support has been removed, to be added back in the future (use a prior
release if LAN is needed).  Basic support for Non-Volatile-Storage is added
to the esp32 module.  And there is also preliminary support for ESP32S2
SoCs and USB, with a GENERIC_S2 board defined.

On the mimxrt and samd ports, USB CDC TX handling has been fixed so that it
now works reliably.

The rp2 port has had many more core Python features enabled, along with the
enabling of ubinascii.crc32(), the uos.VfsFat and machine.Signal classes,
and the uerrno module.  uos.urandom() has been added and machine.freq() can
now change the CPU clock frequency.  The machine.UART class now has support
for timeout/timeout_char, inverted TX/RX lines, and buffered TX/RX with
configurable sized buffers.  For PIO, StateMachine has added restart(),
rx_fifo() and tx_fifo() helper functions, and support for FIFO joining.
There is now support for user C modules (via CMake) and for building
different board configurations (the default remains the PICO board).  USB
reliability has been improved.

For the stm32 port, there is now more configuration options for boards,
such as USBD VID/PID and fine-grained selection of modules.  The UART class
now supports LPUART on L0, L4, H7 and WB MCUs.  WB MCUs have a fix for a
race condition accessing the BLE ACL free buffer list, and a workaround for
a low-level BLE bug.

The zephyr port has been updated to use zephyr v2.5.0, and now builds
MicroPython as a CMake target.

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- rename BYTES_PER_WORD to MP_BYTES_PER_OBJ_WORD
- add .git-blame-ignore-revs for fixing up git blame output

py core:
- gc: don't include mpconfig.h and misc.h in gc.h
- remove BITS_PER_WORD definition
- rename BITS_PER_BYTE to MP_BITS_PER_BYTE
- rename WORD_MSBIT_HIGH to MP_OBJ_WORD_MSBIT_HIGH
- gc: change include of stdint.h to stddef.h
- mpz: fix overflow of borrow in mpn_div
- add core cmake rule files
- expand lists in core cmake custom commands
- mkrules.cmake: rename QSTR_DEFS variables to QSTRDEFS
- mkrules.cmake: add MICROPY_QSTRDEFS_PORT to qstr build process
- nlr: implement NLR for AArch64
- nlrx64: fix typo in comment
- vm: for tracing use mp_printf, and print state when thread enabled
- rename remaining object types to be of the form mp_type_xxx
- py.cmake: move qstr helper code to micropy_gather_target_properties
- py.cmake: introduce MICROPY_INC_CORE as a list with core includes
- profile: resolve name collision with STATIC unset
- runtime: make sys.modules preallocate to a configurable size

extmod:
- vfs_posix_file: allow closing an already closed file
- btstack: add HCI trace debugging option in btstack_hci_uart
- btstack: add stub functions for passkey, l2cap bindings
- btstack: enable SYNC_EVENTS, PAIRING_BONDING by default
- uasyncio: add asyncio.current_task()
- add core cmake rule files
- nimble: ensure handle is set on read error
- moduselect: fix unsigned/signed comparison for timeout!=-1
- uasyncio: add ThreadSafeFlag
- nimble/hal/hal_uart: fix HCI_TRACE format specifiers
- modbluetooth: allow NimBLE to use Zephyr static address
- modussl: fix ussl read/recv/send/write errors when non-blocking
- btstack: use MICROPY_HW_BLE_UART_BAUDRATE for first UART init
- modbluetooth: separate enabling of "client" from "central"
- extmod.cmake: add modonewire.c to MICROPY_SOURCE_EXTMOD list
- modbluetooth: free temp arrays in gatts register services
- re1.5: check and report byte overflow errors in _compilecode
- extmod.cmake: add support to build btree module with CMake

lib:
- tinyusb: update to version 0.8.0
- mbedtls: switch to currently latest commit of LTS branch v2.16
- utils/gchelper_generic: implement AArch64 support
- pico-sdk: update to latest version 1.1.0

drivers: no changes specific to this component/port

mpy-cross: no changes specific to this component/port

Support components
==================

docs:
- library/uasyncio.rst: add docs for ThreadSafeFlag
- develop/cmodules.rst: document C-modules and micropython.cmake
- develop: improve user C modules to properly describe how to build

examples:
- usercmodule: add micropython.cmake to the C and CPP examples
- usercmodules: simplify user C module enabling
- embedding: fix example so it compiles again

tests:
- extmod/vfs_posix.py: add more tests for VfsPosix class
- extmod: add test for ThreadSafeFlag
- multi_bluetooth: add basic performance tests
- rename run-tests to run-tests.py for consistency
- run-tests.py: reformat with Black
- multi_bluetooth: skip tests when BLE features are unsupported
- extmod/vfs_fat_fileio2.py: close test file at end of test
- run-tests.py: provide more info if script run via pyboard crashes
- feature_check: check for lack of pass result rather than failure
- net_inet: add 'Strict-Transport-Security' to exp file

tools:
- add filesystem action examples to pyboard.py help
- ci.sh: change esp32 CI to work with idf.py and IDF v4.0.2
- makemanifest.py: allow passing option args to include()
- ci.sh: update zephyr docker image to v0.11.13
- verifygitlog.py: show required format regexp in error message
- pydfu.py: support DFU files with elements of zero size
- ci.sh: add CI for CMake USER_C_MODULE support
- ci.sh: build user C modules for esp32
- metrics.py: fix esp32 output filename due to move to CMake
- ci.sh: build esp32 using IDF v4.0.2 and v4.3

The ports
=========

all ports:
- remove def of MP_PLAT_PRINT_STRN if it's the same as the default
- update to build with new tinyusb

bare-arm port:
- clean up the code, make it run on an F405, and add a README

cc3200 port: no changes specific to this component/port

esp8266 port:
- modules: fix fs_corrupted() to use start_sec not START_SEC

esp32 port:
- add support to build using IDF with cmake
- esp32_rmt: don't do unnecessary check for unsigned less than zero
- add explicit initialisers to silence compiler warnings
- remove traditional "make" capability
- boards: remove old IDF v3 sdkconfig values
- boards: enable BLE on all boards
- README: update based on new IDF v4 cmake build process
- add support to build with ESP-IDF v4.1.1
- add support to build with ESP-IDF v4.2
- remove obsolete IDF v3 code wrapped in MICROPY_ESP_IDF_4
- modsocket: remove unix socket error code translation
- set MICROPY_USE_INTERNAL_ERRNO=0 to use toolchain's errno.h
- boards: enable size optimisation for builds
- add support to build with ESP-IDF v4.3 pre-release
- add basic support for Non-Volatile-Storage in esp32 module
- make machine.soft_reset() work in main.py and reset_cause()
- define MICROPY_QSTRDEFS_PORT to include special qstrs
- Makefile: specify port and baud on erase_flash command
- machine_hw_spi: use default pins when making SPI if none given
- restore USER_C_MODULE support with new CMake build system
- fix multiple definition errors with mp_hal_stdout_tx functions
- enable btree module
- modsocket: correctly handle poll/read of unconnected TCP socket
- add initial support for ESP32S2 SoCs
- add support for USB with CDC ACM
- boards: add GENERIC_S2 board definition
- machine_pin: use rtc_gpio_deinit instead of gpio_reset_pin

javascript port: no changes specific to this component/port

mimxrt port:
- fix USB CDC handling so it works reliably
- boards: add MIMXRT1050_EVK board, based on MIMXRT1060_EVK
- enable CPYTHON_COMPAT, PY_ASYNC_AWAIT, PY_ATTRTUPLE options

minimal port: no changes specific to this component/port

nrf port:
- drivers/usb: add USBD_IRQHandler which calls tud_int_handler

pic16bit port: no changes specific to this component/port

powerpc port: no changes specific to this component/port

qemu-arm port: no changes specific to this component/port

rp2 port:
- machine_adc: only initialise the ADC periph if not already enabled
- micropy_rules.cmake: fix makemoduledefs vpath to work with abs path
- use local tinyusb instead of the one in pico-sdk
- enable MICROPY_PY_UBINASCII_CRC32 to get ubinascii.crc32()
- enable VfsFat class for FAT filesystem support
- machine_uart: add timeout/timeout_char to read and write
- machine_uart: add support for inverted TX and RX lines
- rp2_pio: allow more than 8 consecutive pins for PIO out/set/sideset
- rp2_pio: fix sm.get(buf) to not wait after getting last item
- modmachine: allow changing CPU clock frequency
- modmachine: re-init UART for REPL on frequency change
- rp2_flash: prevent MICROPY_HW_FLASH_STORAGE_BASE being set negative
- enable uerrno module
- enabled more core Python features
- modmachine: enable machine.Signal class
- use core-provided cmake fragments instead of custom ones
- mpthreadport.h: cast core_state to _mp_state_thread_t
- add support for USER_C_MODULES to CMake build system
- don't advertise remote wakeup for USB serial
- CMakeLists.txt: enable USB enumeration fix
- import uarray instead of array in rp2 module
- rp2_pio: validate state machine frequency in constructor
- moduos: implement uos.urandom()
- rp2_pio: add StateMachine restart,rx_fifo,tx_fifo helper functions
- machine_uart: add buffered transfer of data with rxbuf/txbuf kwargs
- add support for building different board configurations
- rp2_pio: add fifo_join support for PIO

samd port:
- mphalport: fix USB CDC tx handling to work reliably

stm32 port:
- uart: add uart_set_baudrate function
- mpbthciport: only init the uart once, then use uart_set_baudrate
- mboot: add unpack-dfu command to mboot_pack_dfu.py tool
- usb: allow a board to configure USBD_VID and all PIDs
- make pyb, uos, utime, machine and onewire modules configurable
- boards: disable onewire module on boards with small flash
- mpbthciport: fix initial baudrate to use provided value
- mpbthciport: use mp_printf instead of printf for error message
- mpbtstackport: allow chipset and secondary baudrate to be set
- mboot: after sig verify, only write firmware-head if latter valid
- uart: add support for LPUART1 on L0, L4, H7 and WB MCUs
- boards/NUCLEO_WB55: enable LPUART1 on PA2/PA3
- enable MICROPY_PY_UBINASCII_CRC32 to get ubinascii.crc32()
- rfcore: allow BLE settings to be changed by a board
- storage: prevent attempts to read/write invalid block addresses
- make-stmconst.py: allow "[]" chars when parsing source comments
- main: fix passing state.reset_mode to init_flash_fs
- powerctrl: save and restore EWUP state when configuring standby
- spi: fix baudrate calculation for H7 series
- boardctrl: add MICROPY_BOARD_STARTUP hook
- Makefile: fix C++ linker flags when toolchain has spaces in path
- Makefile: allow QSTR_DEFS,QSTR_GLOBAL_DEPENDENCIES to be extended
- include .ARM section in firmware for C++ exception handling
- powerctrl: allow a board to configure AHB and APB clock dividers
- powerctrl: support using PLLI2C on STM32F413 as USB clock source
- boards/pllvalues.py: relax PLLQ constraints on STM32F413 MCUs
- mpconfigport.h: add support for a board to specify root pointers
- boardctrl: give boards control over execution of boot.py,main.py
- boards/NUCLEO_L476RG: add 5 remaining UARTs
- rfcore: fix race condition with C2 accessing free buffer list
- rfcore: intercept addr-resolution HCI cmd to work around BLE bug
- boards: split UARTx_RTS_DE into UARTx_RTS/UARTx_DE in pin defs
- uart: use LL_USART_GetBaudRate to compute baudrate
- sdram: make MICROPY_HW_FMC_BA1,MICROPY_HW_FMC_A11 optional pins

teensy port: no changes specific to this component/port

unix port:
- mpbtstackport_common: implement mp_bluetooth_hci_active
- moduselect: don't allow both posix and non-posix configurations
- improve command line argument processing
- main: make static variable that's potentially clobbered by longjmp

windows port: no changes specific to this component/port

zephyr port:
- update to zephyr v2.5.0
- disable frozen source modules
- remove unused build files
- build MicroPython as a cmake target
- boards: add support for the nucleo_h743zi board
- modusocket: fix parameter in calls to net_context_get_XXX()

New rp2 port, BLE pairing, bonding and l2cap APIs, and docs on internals

This release of MicroPython sees the addition of a new "rp2" port for the
new Raspberry Pi RP2040 microcontroller, a dual-core Cortex-M0+ MCU with
programmable IO.  This port is built on the pico-sdk and MicroPython sits
very close to the bare metal.  The programmable IO is supported via the
@rp2.asm_pio decorator which allows writing inline assembler to be run on
the PIO state machines.

The ubluetooth module has seen significant improvements, fixes and
additions.  BLE events are now synchronous on unix and stm32 so that user
Python callbacks are called directly from the BLE stack (from NimBLE).
This helps with the new pairing and bonding API.  There is also a new l2cap
API for much faster raw data transfer between BLE devices.

Many new sections have been added to the existing "Developing and building
MicroPython" chapter to make it all about the internals of MicroPython,
including details about the MicroPython compiler, and how to port to a new
system.  This documentation work was done as part of Google's Season of
Docs 2020.

The native emitter and inline assembler now fully support ARMv6M, for
Cortex-M0+ CPUs.  There is also support added for C++ user modules on
unix, stm32 and esp32.  And reproducible builds can now be achieved by
setting SOURCE_DATE_EPOCH in the shell build environment.  Qstr
preprocessing is now done in parallel to speed up building, and there is
a new tools/ci.sh script with all functionality to run the continuous
integration tests.

The machine.I2C and machine.SPI classes have been modified so they no
longer construct both software- and hardware-based peripheral instances.
Such construction is now split to explicit soft and non-soft types by the
introduction of machine.SoftI2C and machine.SoftSPI classes.  See below for
more information.

The wait_for function in uasyncio now handles cancellation correctly,
VfsLfs supports mounting in read-only mode, and the urandom module will
randomise its seed on import on stm32, esp8266, esp32 and rp2 ports.

A new raw-paste mode is added to the REPL which includes flow control
between the device and host, as well as a mechanism where the device pulls
in data from the host as it parses the input.  This makes pasting code
faster, more reliable and use less memory.  This feature is supported on
all ports that have a raw REPL and still supports previous REPL behaviour.
See the documentation for more detail on this raw-paste mode.

The stm32 port sees improved rfcore support for WB MCUs, including flash
locking for writes when BLE is active, and a script for automatic update of
FUS/WS firmware.  New hooks are added for boards to configure the top level
behaviour of the system in stm32_main, and there is now support for
Ethernet on H7 processors.  Mboot now allows signed and encrypted firmware
updates.

Breaking changes in this release are:

- The "sys" module is renamed to "usys".  Ports that do not enable module
  weak links must replace "import sys" with "import usys as sys".
  See commit 40ad8f1666b265dafc7844d765f45cfae4b6299f

- machine.I2C and machine.SPI constructors are changed when using
  software-based I2C and SPI.  Code that constructed I2C/SPI peripherals in
  the following way will need to be changed (or else their use will emit a
  warning which will eventually be an error):

    machine.I2C(-1, ...)            ->  machine.SoftI2C(...)
    machine.I2C(scl=scl, sda=sda)   ->  machine.SoftI2C(scl=scl, sda=sda)

    machine.SPI(-1, ...)            ->  machine.SoftSPI(...)
    machine.SPI(sck=sck, mosi=mosi, miso=miso)
                        ->  machine.SoftSPI(sck=sck, mosi=mosi, miso=miso)

  Code which uses machine.I2C and machine.SPI classes to access hardware
  peripherals does not need to change.
  See commits 39d50d129ce428858332523548f0594503d0f45b and
  98182a97c5a9229938406beb722966eacceeb823

- In ubluetooth, the BLE.irq() method now has positional only arguments.
  See commit 6a6a5f9e151473bdcc1d14725d680691ff665a82

- In ubluetooth, arguments passed to the BLE.irq() callback that were
  previously bytes objects are now memoryview objects.
  See commit 81f2162ca0e926c9a4a1787a3863d94d86be0b36

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- rename "sys" module to "usys"
- rename absolute time-based functions to include "epoch"

py core:
- objfloat: fix handling of negative float to power of nan
- fix handling of NaN in certain pow implementations
- showbc: pass in an mp_print_t struct to all bytecode-print functions
- parse: pass in an mp_print_t to mp_parse_node_print
- dynruntime.h: add mp_import_* and mp_load/store_*
- objstr: make bytes(bytes_obj) return bytes_obj
- objarray.h: add mp_obj_memoryview_init() helper function
- makeversionhdr.py: match only git tags which look like versions
- parse: expose rule-name printing as MICROPY_DEBUG_PARSE_RULE_NAME
- objdict: add mp_const_empty_dict_obj, use it for mp_const_empty_map
- objtype: handle __dict__ attribute when type has no locals
- scope: name and use id_kind_type_t
- objexcept: compare mp_emergency_exception_buf_size signed
- use unsigned comparison of chars
- add explicit initializers for default values
- vmentrytable: ignore GCC -Woverride-init
- introduce and use MP_FALLTHROUGH macro
- makeqstrdefs.py: fix beaviour when scanning non-C preprocessed files
- makeqstrdefs.py: process C++ files as well
- mkrules.mk: add target for compiling C++ files
- makeqstrdefs.py: support preprocessing C++ files for QSTR generation
- workaround clang error when building misc.h with C++ compiler
- py.mk: support C++ code for user C modules
- mpz: do sign extension in mpz_as_bytes for negative values
- binary: fix sign extension setting wide integer on 32-bit archs
- mpprint: prevent case fall-through when assert is disabled
- mpprint: fix length calculation for strings with precision-modifier
- modmath: simplify handling of positional args to reduce code size
- mkrules.mk: remove stray vpath and unused -Itmp, add $(Q) for $(AR)
- objfun: support fun.__globals__ attribute
- asmthumb: add support for ARMv6M in native emitter
- emitnative: ensure encoding to load prelude_offset doesn't change sz
- emitinlinethumb: exclude code using #if when ARMV7M disabled
- emitnative: support binary ops on ARMv6M without use of ite instr
- qstr.h: remove QSTR_FROM_STR_STATIC macro
- gc: fix debug printing of pointer
- persistentcode: introduce MICROPY_PERSISTENT_CODE_SAVE_FILE option
- makeversionhdr: honor SOURCE_DATE_EPOCH if present

extmod:
- modbluetooth: rename logging macro to be just DEBUG_printf
- modbluetooth: refactor stack/hci/driver/port bindings
- nimble: set struct alignment correctly on 64-bit arch
- nimble: make nimble_malloc work with allocated size
- nimble: implement NimBLE mutex
- modbluetooth: implement configuration of address modes
- modbluetooth: allow using mp_hal_get_mac as a static address
- btstack: add btstack support for _IRQ_GATTS_READ_REQUEST
- btstack: detect HCI UART init failure
- nimble: add timeout for HCI sync on startup
- modussl_axtls: reduce size of code that makes exception
- modbluetooth: fix handling of optional data/uuid args
- modbluetooth: make BLE.irq() method positional only
- modbluetooth: print UUIDs correctly
- modbluetooth: implement MTU
- vfs: fix lookup of entry in root dir so it fails correctly
- modbluetooth: change module-owned bytes objects to memoryview
- modure: allow \\ in re.sub replacements
- machine_i2c: rename type to SoftI2C and add custom print method
- machine_i2c: remove "id" arg in SoftI2C constructor
- machine_spi: remove "id" arg in SoftSPI constructor
- utime_mphal: add generic utime.time_ns() function
- add explicit initializers for default values
- disable -Wmissing-field-initializers for lfs2
- introduce and use MP_FALLTHROUGH macro
- vfs_lfs: support mounting LFS filesystems in read-only mode
- modurandom: support urandom.seed() without an argument
- btstack/btstack.mk: add -Wimplicit-fallthrough=0
- nimble/nimble.mk: add -Wno-old-style-declaration
- moductypes: fix storing to (U)INT64 arrays on 32-bit archs
- machine_mem: only allow integers in machine.memX subscript
- modbluetooth: make UUID type accessible outside modbluetooth.c
- modbluetooth: combine gattc-data-available callbacks into one
- nimble: poll startup directly rather than using NimBLE sem
- modbluetooth: re-instate optional no-ringbuf modbluetooth
- nimble: make stm32 and unix NimBLE ports use synchronous events
- machine_i2c: add init protocol method for generic I2C bindings
- modbluetooth: add API for L2CAP channels
- nimble/modbluetooth_nimble: fix build when l2cap unavailable
- uasyncio: delay calling Loop.call_exception_handler by 1 loop
- uasyncio: add Task.done() method
- uasyncio: fix cancellation handling of wait_for
- nimble: fail read if the characteristic is too big
- modbluetooth: add _IRQ_CONNECTION_UPDATE event
- modbluetooth: allow setting char/desc enc/auth options
- modbluetooth: allow user-specified reason in read request IRQ
- modbluetooth: add compile-config flag to enable pairing/bonding
- modbluetooth: add _IRQ_ENCRYPTION_UPDATE event
- modbluetooth: allow configuration of pairing/bonding parameters
- modbluetooth: add gap_pair(conn_handle) func to intiate pairing
- modbluetooth: add support for bonding (key persistence)
- modbluetooth: simplify synchronous invoke_irq_handler signature
- modbluetooth: add support for passkey authentication
- nimble: generate and persist a unique IRK
- modubinascii: update code, docs for hexlify now CPython has sep
- vfs: raise OSError(ENODEV) if mounting bdev without a filesystem
- nimble: reset NimBLE BSS in mp_bluetooth_init
- nimble: don't assert on save-IRK failure
- modbluetooth: add ble.hci_cmd(ogf, ocf, req, resp) function
- vfs: check block 0 and 1 when auto-detecting littlefs
- modframebuf: change int to unsigned int in format methods args
- modonewire: use pin_od_high/pin_od_low instead of pin_write
- nimble: improve the flow control for l2cap recv path

lib:
- libm: reduce size of static two_over_pi array
- utils/mpirq: add mp_irq_init func, and clean up unused init method
- utils/pyexec: add MICROPY_BOARD hooks before/after executing code
- utils/pyexec: add stdin-reader on raw REPL with flow control
- littlefs: update littlefs2 to v2.3.0
- littlefs: guard lfs2_mlist_isopen with LFS2_NO_ASSERT
- stm32lib: update library for WB v1.10.0
- libhydrogen: add new libhydrogen submodule
- timeutils: provide simple impl of extra funcs when Epoch is 1970
- pico-sdk: add new pico-sdk submodule, for the rp2 port
- utils/pyexec: remove obsolete LCD initialization
- pico-sdk: update to latest version v1.0.1

drivers:
- memory/spiflash: add MICROPY_HW_SPIFLASH_ENABLE_CACHE option

mpy-cross:
- enable more warnings

Support components
==================

docs:
- library/ubluetooth.rst: document BLE address modes
- library/ubluetooth.rst: clarify position/kw arguments
- library/ubluetooth.rst: clarify peripheral/central vs server/client
- library/ubluetooth.rst: add docs for MTU API
- develop: add notes on prerequisite tools for building native .mpy
- reference/packages.rst: fix typo, remove duplicate "port"
- update I2C and SPI docs to add reference to SoftI2C and SoftSPI
- library/btree.rst: correct method typo: __detitem__ to __delitem__
- library/machine.rst: correct minor typo: timout to timeout
- library/machine.Signal.rst: correct typo: usecases to use cases
- library/machine.Timer.rst: add mention of constructor arguments
- reference/glossary.rst: fix minor grammar error, An -> A
- fix reference to QSTR_GEN_CFLAGS Makefile flag
- develop/cmodules.rst: add link to source code for user C example
- library/ubluetooth.rst: add docs for L2CAP channels
- reference/repl.rst: add information about new raw-paste mode
- library/ubluetooth.rst: add _IRQ_CONNECTION_UDPATE docs
- library/ubluetooth.rst: update char/desc flags
- library/ubluetooth.rst: update read request IRQ docs
- library/ubluetooth.rst: add pairing/bonding config docs
- library/ubluetooth.rst: add gap_pair() docs
- library/ubluetooth.rst: add bonding docs
- library/ubluetooth.rst: add passkey docs
- develop: add MicroPython Internals chapter
- fix minor typos in RTC docs, and->an
- esp8266/quickref: add warning block about NeoPixel timing
- develop/natmod: fix a small typo, con->can
- update copyright year range to include 2021

examples:
- bluetooth: update to use positional-only args to irq()
- add example code for user C modules, both C and C++
- bluetooth: add bonding/passkey demo
- rp2: add pio_uart_rx.py example

tests:
- multi_bluetooth: update to new config('mac') behaviour
- multi_bluetooth: make ble_gap_connect robust against event timing
- multi_bluetooth: update UUID format in .exp files
- run-multitests.py: show test/truth diff
- multi_bluetooth/ble_mtu.py: add multitest for BLE MTU
- basics: enable == and != special-method tests now that they work
- basics: add test for MICROPY_PY_ALL_INPLACE_SPECIAL_METHODS ops
- run-tests: use -BS flags when running CPython
- thread/stress_schedule.py: assign globals before running test
- micropython/extreme_exc.py: unlink alloc'd lists earlier in chain
- run-multitests.py: fix diff order, show changes relative to truth
- multi_bluetooth: improve reliability of event waiting
- run-multitests.py: add a -p flag to run permutations of instances
- multi_bluetooth: change dict index-and-del to pop, to clear event
- multi_bluetooth: add a test for WB55 concurrent flash access
- multi_bluetooth: add L2CAP channels multi-test
- extmod: add vfs_posix.py test for uos.VfsPosix class
- run-tests: update skipped tests on CI for GitHub Actions
- multi_bluetooth: add multitests for BLE pairing and bonding
- misc/sys_settrace_features.py: ignore CPython zipimport traces
- extmod: add test to try and mount a block device directly
- misc/sys_settrace: make test output independent of invoked path
- misc/sys_settrace_features.py: fix running with non-dflt encoding
- extmod: add test for the precision of utime functions
- move native for test from pybnative to micropython
- extmod/utime_time_ns.py: relax bounds on time_ns measurement
- run-tests: change default Python command used on Windows

tools:
- mpy-tool.py: fix merge of multiple mpy files to POP_TOP correctly
- write msvc-compatible frozen content
- upip.py: support explicit port number in host
- makeqstrdefs.py: run qstr preprocessing in parallel
- ci.sh: add helper script to run CI tasks
- pyboard.py: add fast raw-paste mode
- ci.sh: put echo of CI path in a separate function
- ci.sh: use pip-install to get latest version of esptool.py
- ci.sh: pip install pyhy for stm32 builds
- ci.sh: for code size build, fetch history of master branch only
- ci.sh: for ci_code_size_setup, update apt to install gcc-multilib
- mpy-tool.py: list frozen modules in MICROPY_FROZEN_LIST_ITEM
- verifygitlog.py: add script for verifying commit message format
- makemanifest.py: add check that freeze path is a directory
- remove obsolete upip bootstrap script

CI:
- install setuptools for black code formatting
- update zephyr build to v2.4.0
- stop using Travis for CI
- workflows: add workflows for all CI tasks, builds and tests
- workflows: run unix and qemu-arm workflows when tests change
- workflows: fix code-size CI workflow
- workflows: add CI workflow for rp2 port
- workflows: add workflow to verify commit message format
- workflows/ports_unix.yml: add job for a reproducible build

The ports
=========

all ports:
- add utime.gmtime() function
- add SoftI2C and SoftSPI to machine module where appropriate
- support legacy soft I2C/SPI construction via id=-1 arg
- use correct in/out endpoint size in TUD_CDC_DESCRIPTOR

cc3200 port:
- ftp: add quotes to PWD response and allow FEAT prior to login
- fix debug build

esp8266 port:
- remove release-specific manifest, disable osdebug by default
- mpconfigport.h: seed the urandom module on import
- remove "FAT" from warning message in inisetup.py
- modules/neopixel.py: add timing param to NeoPixel constructor

esp32 port:
- pin MicroPython and NimBLE tasks to core 0
- mpconfigport.h: remove duplicate uhashlib registration
- boards/sdkconfig.base: set default IDF log level to ERROR
- modnetwork: re-enable PPP support for IDF-SDK >=v4
- use path relative to root for netutils/timeutils headers
- mpconfigport.h: enable MICROPY_PY_DELATTR_SETATTR
- mpconfigport.h: seed the urandom module on import
- support building C++ code
- machine_pin: reset pin if init sets mode
- remove "FAT" from warning message in inisetup.py
- modnetwork: synchronize WiFi AUTH_xxx constants with IDF values

javascript port: no changes specific to this component/port

mimxrt port:
- boards: add MIMXRT1064_EVK board

minimal port: no changes specific to this component/port

nrf port:
- main: make mp_builtin_open signature match that in py/builtin.h
- remove unnecessary includes of mpconfigport.h and its header guard
- README: describe Pin numbering scheme for nRF52840
- boards: update memory.ld to include bootloader offsets
- Makefile: add bootloader specific section
- Makefile: add support for flashing with nrfutil
- boards: add linker script for nrf52840 Open Bootloader 1.2.0
- change selected boards to utilize pre-flashed bootloader
- README: add use of "make submodules" in alternative build paragraph

pic16bit port: no changes specific to this component/port

powerpc port: no changes specific to this component/port

qemu-arm port: no changes specific to this component/port

rp2 port:
- add new port to Raspberry Pi RP2 microcontroller
- machine_pin: change N_GPIOS to NUM_BANK0_GPIOS for pico-sdk compat
- memmap_mp.ld: update for latest SDK
- rp2_pio: add JMP PIN support for PIO
- modmachine: implement additional functions incl unique_id and idle

samd port: no changes specific to this component/port

stm32 port:
- mpconfigport.h: enable MICROPY_PY_REVERSE_SPECIAL_METHODS
- uart: allow static IRQ handler registration
- modbluetooth_hci: use a static mp_irq_obj_t for BT HCI UART IRQ
- mpbthciport: increase char timeout of BT HCI UART
- make-stmconst.py: add support for WB55 header files
- rfcore: update rfcore.c to match how ST examples work
- boards/USBDONGLE_WB55: add USE_MBOOT support
- powerctrlboot: acquire HSEM5 on STM32WB during SystemClock_Config
- rfcore: fix length matching in HCI parser
- rfcore: refactor some helper funcs, and remove some magic numbers
- rfcore: enable RX IRQ on BLE IPCC channel for better performance
- boards/NUCLEO_WB55: add Python helper code for rfcore
- usb: don't nul pyb_hid_report_desc if MICROPY_HW_USB_HID disabled
- rtc.h: include py/obj.h to make header self contained
- servo: fix angle and speed methods to work again with -ve args
- led: support PWM output without TIM3
- rfcore: fix FUS layout and size of ipcc_device_info_table_t
- Makefile: allow boards to extend SRC_C, SRC_O and OBJ variables
- sdio: don't change any DMA2 settings on H7 MCUs
- sdcard: fix H7 build when using SDMMC2
- rfcore: add Python API for basic rfcore operations
- boards/NUCLEO_WB55: add standalone WB55 FUS/WS firmware updater
- rfcore: update to support WS=1.9.0.0.4
- boards/NUCLEO_WB55/rfcore_firmware.py: fix flash unlock
- boards/NUCLEO_WB55/rfcore_firmware.py: fix bad variable name
- boards/NUCLEO_WB55/rfcore_firmware.py: increase GET_STATE timeout
- fix broken build when FAT FS multi-partition is disabled
- usbd_cdc_interface: check and handle CDC TX wrap-overflow
- machine_adc: fix ADC auto-calibration to run when ADC not enabled
- mpconfigport.h: seed the urandom module on import
- rng: use SysTick+RTC+unique-id to seed pRNG for MCUs without RNG
- boards: factor out common data/bss/heap/stack linker sections
- support C++ code and user C modules written in C++
- main: move update_reset_mode to outside the soft-reset loop
- add MICROPY_BOARD calls in various places in stm32_main
- boardctrl: define MICROPY_BOARD_EARLY_INIT alongside others
- Makefile: make the generation of `firmware.bin` explicit
- Makefile: allow boards to extend all SRC variables
- rtc: validate the RTC prescaler on boot and change if incorrect
- rfcore: make RX IRQ schedule the NimBLE handler
- flash: implement WB55 flash locking
- rfcore: don't send HCI ACL cmds while another is pending
- rfcore: depend on NimBLE only when BLE enabled
- modmachine: add device and revision ids to machine.info()
- Makefile: disable text compression in debug builds
- powerctrl: define RCC_SR_SFTRSTF flag for H747
- powerctrl: fix STOP mode voltage scaling on H7 REV V devices
- powerctrl: on H7, re-enable disabled OSCs/PLLs on exit from STOP
- powerctrl: disable RTC write protection before changing flags
- powerctrl: set H7 RTC wakeup flags
- powerctrl: ensure SysTick is disabled on STOP mode entry for H7
- i2c: factor I2C finding code to i2c_find_peripheral function
- add support for a board to reserve certain peripherals
- Makefile: change -O0 to -Og for DEBUG=1 builds
- boards/stm32h743.ld: enable D2 RAM and add eth-buffer section
- eth: add support for H7 processors
- boards/NUCLEO_H743ZI: enable ethernet peripheral
- mboot: enable LFS2_READONLY for mboot builds with littlefs
- usb: allocate 128 bytes to CDC data out EPs on non-multi-OTG MCUs
- pyb_can: add ability to calculate CAN bit timing from baudrate
- system_stm32: enable DBGMCU in low-power modes for debug builds
- sdram: add SDRAM enter/leave self-refresh mode functions
- adc: deselect VBAT after reading to prevent battery drain
- main: do extended readblocks call when auto-detecting littlefs
- boards/PYBD_SF2: disable SPIFLASH_ENABLE_CACHE for mboot builds
- mboot/gzstream: fix lost data decompressing final part of file
- mboot: add support for signed and encrypted firmware updates
- boards/NUCLEO_WB55: enable MBOOT with packing mode
- Makefile: use MBOOT_PACK_KEYS_FILE as depedency of .pack.dfu
- main: check block 0 and 1 when auto-detecting littlefs
- mboot: don't auto-detect littlefs block size
- mboot: add ELEM_TYPE_STATUS element so application can get status
- mboot: introduce MBOOT_ERRNO_xxx constants and use them
- mboot/fwupdate.py: refactor update_mpy with support for STATUS
- main: introduce MICROPY_HW_FLASH_MOUNT_AT_BOOT config option
- rfcore: fix flow control for IPCC RX IRQ
- fix minor typos in RTC docs, and->an
- usbd_cdc_interface: don't wait in usbd_cdc_tx_always if suspended
- mboot: change debug compiler optimisation from -O0 to -Og

teensy port:
- fix build errors and warnings and enable -Werror

unix port:
- Makefile: always enable -f*-sections regardless of DEBUG setting
- implement BLE H4 HCI UART for btstack/nimble
- implement mp_hal_time_ns using gettimeofday
- variants: enable MICROPY_DEBUG_PARSE_RULE_NAME on coverage build
- mpconfigport.h: enable MICROPY_PY_DELATTR_SETATTR
- enable more warnings
- support building C++ code
- Makefile: move coverage.c and coveragecpp.cpp to coverage variant
- handle pending events/scheduler in MICROPY_EVENT_POLL_HOOK
- make mp_hal_delay_ms run MICROPY_EVENT_POLL_HOOK
- modtime: fix time() precision on unix ports with non-double floats

windows port:
- msvc: support freezing modules
- Makefile: support freezing modules
- show test failures in the Appveyor builds
- update build instructions in README
- implement mp_hal_time_ns using gettimeofday
- msvc: use same default python command as core

zephyr port:
- replace zephyr integer types with C99 types
- const-ify struct device instance pointers
- update build instructions to v2.4.0
- replace broken shell_net_iface() with more general shell_exec()
- guard I2C code with appropriate ifdef config
- add basic UART functionality to machine module
- machine_uart: fix arg of machine_uart_ioctl to make it uintptr_t

New uasyncio module, code formatting, BTstack bindings with unix support

This release of MicroPython includes a new implementation of the uasyncio
module which aims to be more compatible with CPython's asyncio module.  The
main change is to use a Task object for each coroutine, allowing more
flexibility to queue tasks in various places, eg the main run loop, tasks
waiting on events, locks or other tasks.  It no longer requires
pre-allocating a fixed queue size for the main run loop.  A pairing heap is
used to queue Tasks, and the core is optionally implemented in C.

Most code in this repository is now auto-formatted using uncrustify for C
code and Black for Python code.  The tools/codeformat.py script is used to
apply this formatting.  Options for uncrustify were chosen to match as
closely as possible the existing C style, but there were nevertheless quite
a few changes to make the code style consistent.

BlueKitchen BTstack bindings have been added for the ubluetooth module, as
an optional alternative to the NimBLE stack.  The unix port can now be
built with BLE support using these bindings, which works with USB Bluetooth
adaptors (this feature is enabled by default on the dev and coverage
variants).

Other Bluetooth additions include: new events for service/characteristic/
descriptor discovery complete; new events for read done and indicate
acknowledgement; and support for active scanning in BLE.gap_scan().  See
also below for breaking changes to the ubluetooth BLE API.

PEP 526 has been implemented which adds new syntax for variable
annotations, such as "x:int = 1".  PEP 572 has also been implemented, which
adds the ":=" operator for assignment expressions, such as "if x := 1:...".

The whole code base now supports compressing error messages (those strings
used as arguments to exception instances) using a "common word" scheme,
which can be used to reduce code size.

Other new features include: support for non-boolean results for equality
and inequality tests; the addition of the micropython.heap_locked()
function to test the state of the heap; binary operations for viper uint
operands in the native emitter; and mtime support on littlefs v2
filesystems (which can be disabled if needed).

There has been an important bug fix when importing ARM machine code from
an .mpy file: the system now correctly tracks the executable memory
allocated to the machine code so this memory is not reclaimed by the
garbage collector.

For testing, a multi-instance test runner has been added (see
tests/run-multitests.py) which allows running a synchronised test across
two or more MicroPython targets.  This is currently used for network and
BLE tests that require communication between multiple devices.

In the unix port different builds are now organised into build variants,
analogous to boards on bare-metal.  And PEP 475 has been implemented which
retries syscalls failing with EINTR.

The stm32 port sees improved support for STM32WB MCUs, with ADC, SPI and
DMA support, along with support in mboot for these MCUs.  Mboot also adds
optional littlefs support.

The esp8266 port now includes three generic board definitions:
GENERIC_512K, GENERIC_1M and GENERIC, with the latter for modules with 2M
or more of flash.  This port also changed the default filesystem to
littlefs, and no longer supports hard pin IRQs.  See breaking changes below
for more details.

The esp32 port now enables Bluetooth support (via NimBLE) on both IDF v3
and v4 builds.  It also changes the default filesystem from FAT to littlefs
v2 (but existing devices with FAT filesystems will continue to work without
change).

There is also a new mimxrt port which targets NXP i.MX RT series CPUs.

Breaking changes in this release are:

- async-for no longer await's on the result of __aiter__.  The __aiter__
  method should return an async-iterable object but is not itself
  awaitable.
  See commit 37e1b5c891f9964bb6c95228bc2d718511507a69

- In ubluetooth, the IRQ event constants have all changed value (from a
  bitfield to a sequential integer) and Python code should be updated
  accordingly by replacing the const definitions with the new ones, which
  can be found at
  https://docs.micropython.org/en/latest/library/ubluetooth.html#ubluetooth.BLE.irq
  See also commit e6881f08292d03f089185718c131f543d095089b

- In ubluetooth, the IRQ data for the _IRQ_SCAN_RESULT event has had the
  "connectable" entry changed to "adv_type".  The existing connectable
  value was a boolean and True now becomes 0x00, False becomes 0x02.
  See commit dd0bc26e65734b8a4fafa3769008e92e2ec6645d

- For esp8266, the default filesystem has changed from FAT to littlefs v2.
  And the flash layout of the firmware and filesystem has changed to give
  more space to the firmware and frozen bytecode.  When upgrading an
  existing esp8266 device the filesystem will be reformatted so files
  should be backed up first.
  See commit e0905e85a7ad2961aa9192f6130565860e531ad3

- For esp8266, machine.Pin no longer supports configuring a pin IRQ with
  "hard=True" (because the interrupt handling code is moved to iRAM).
  Existing code using pin IRQs should remove any "hard=True" argument.
  See commit 0bd58a56137bd9124756ed0f57b4213daccfc7d5

- For the unix port, binaries are renamed to micropython-variant (no longer
  micropython_variant).
  See commit 977b532c8fcd1a9e12844dd4f9cc2d70341013d7

What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.

Main components
===============

all:
- reformat C and Python source code with tools/codeformat.py
- convert exceptions to use mp_raise_XXX helpers in remaining places
- remove spaces between nested paren and inside function arg paren
- remove spaces inside and around parenthesis
- fix implicit casts of float/double, and signed comparison
- use MP_ERROR_TEXT for all error messages
- clean up error strings to use lowercase and change cannot to can't
- fix implicit floating point promotion
- fix implicit conversion from double to float
- fix implicit floating point to integer conversions
- enable extra conversion warnings where applicable
- remove commented-out include statements
- format code to add space after C++-style comment start
- factor gchelper code to one place and use it for unix & ARM ports
- fix auto-enable of MICROPY_GCREGS_SETJMP to select GC behaviour
- update Python code to conform to latest black formatting

py core:
- remove commented-out debug printf's from emitbc and objlist
- obj.h: remove comments about additional mp_buffer_info_t entries
- objobject: add object.__setattr__ function
- objobject: add object.__delattr__ function
- nlrx86: silence possible warnings about unused nlr argument
- asmx86: fix stack to be 16-byte aligned for entry and sub-call
- asmx86: remove unused 5th argument facility
- runtime: don't allocate iter buf for user-defined types
- objsingleton: use mp_generic_unary_op for singleton objects
- introduce MP_ROM_NONE macro for ROM to refer to None object
- introduce MP_ROM_FALSE/MP_ROM_TRUE for ROM to refer to bool objects
- objstr: don't use inline GET_STR_DATA_LEN for object-repr D
- obj.h: use 32-bit shift in MP_OBJ_NEW_QSTR calc for obj-repr D
- clean up commented-out code and comments about exception hierarchy
- objslice: add support for indices() method on slice objects
- objslice: inline fetching of slice paramters in str_subscr()
- make mp_obj_get_type() return a const ptr to mp_obj_type_t
- mkenv.mk: move usage of 32-bit flags to py.mk
- unicode: add unichar_isalnum()
- runtime: move MICROPY_PORT_INIT_FUNC near the end of mp_init()
- nativeglue: use mp_const_X instead of &mp_const_X_obj
- obj.h: redefine qstr object encoding to add immediate obj encoding
- obj: add MICROPY_OBJ_IMMEDIATE_OBJS option to reduce code size
- obj: optimise mp_obj_get_type for immediate objs with repr A and C
- mpconfig.h: define BITS_PER_BYTE only if not already defined
- objint: add mp_obj_int_get_uint_checked() helper
- pairheap: add generic implementation of pairing heap data structure
- gc: don't include or init gc_mutex when GIL is enabled
- qstr: don't include or init qstr_mutex when GIL is enabled
- objgenerator: use mp_obj_new_exception_arg1 to make StopIteration
- objexcept: optimise mp_obj_new_exception[_arg1/_args] functions
- obj.h: add and use mp_obj_is_bool() helper
- release GIL during syscalls in reader and writer code
- emitnative: use NULL for pending exception (not None)
- emitnative: stop after finding an unwind target
- mpthread.h: use strong type for mp_thread_set_state() argument
- objtype: make mp_obj_type_t.flags constants public, moved to obj.h
- support non-boolean results for equality and inequality tests
- compile: allow 'return' outside function in minimal builds
- scheduler: add "raise_exc" argument to mp_handle_pending
- scheduler: move mp_keyboard_interrupt from lib/utils to py core
- scheduler: allow a port to specify attrs for mp_keyboard_interrupt
- scheduler: move clearing of kbd traceback to mp_keyboard_interrupt
- expand type equality flags to 3 separate ones, fix bool/namedtuple
- add mp_raise_type helper macro and use it where appropriate
- add mp_raise_msg_varg helper and use it where appropriate
- factor out definition of mp_float_union_t to one location
- objexcept: rename mp_obj_new_exception_msg_varg2 to ..._vlist
- objtuple: remove code that handles tuple-subclass equality test
- objtype: allow mp_instance_cast_to_native_base to take native obj
- dynruntime.h: add implementation of mp_obj_cast_to_native_base
- objarray: turn on MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE for memoryview
- removing dangling "else" to improve code format consistency
- bc0.h: shift comment to start of line to improve format consistency
- builtinimport: adjust if-block order in find_file to clean up #if's
- malloc: put { on separate line for funcs that have selective sigs
- un-nest configuration #if/#endif's for selection of complex code
- parse: add parenthesis around calculated bit-width in struct
- builtinevex: support passing in a bytearray/buffer to eval/exec
- objstr: remove duplicate % in error string
- objstringio: expose tell() on StringIO and BytesIO objects
- modmicropython: add heap_locked function to test state of heap
- stream.h: include sys/types.h to get size_t and off_t for POSIX API
- mpconfig.h: enable MICROPY_MODULE_GETATTR by default
- pairheap: properly unlink node on pop and delete
- pairheap: add helper function to initialise a new node
- use preprocessor to detect error reporting level (terse/detailed)
- dynruntime.mk: set MICROPY_ENABLE_DYNRUNTIME instead of per module
- implement "common word" compression scheme for error messages
- objexcept: allow compression of exception message text
- parse: remove unnecessary check in const folding for ** operator
- objexcept: remove optional TimeoutError exception
- scheduler: fix race in checking scheduler pending state
- scheduler: add assert that scheduler is locked when unlocking
- makecompresseddata.py: don't prefix str with mark if not compressed
- scope: add assert to check that low numbered qstrs do fit in uint8_t
- always give noop defines when MICROPY_ROM_TEXT_COMPRESSION disabled
- objarray: fix sign mismatch in comparison
- objint: do not use fpclassify
- makecompresseddata.py: make compression deterministic
- objdict: fix popitem for ordered dicts
- stream: remove mp_stream_errno and use system errno instead
- modio: allow uio.IOBase streams to return errno for read/write error
- scheduler: add option to wrap mp_sched_schedule in arbitrary attr
- parse: support constant folding of power operator for integers
- scheduler: convert mp_sched_full and mp_sched_num_pending to macros
- parse: make mp_parse_node_extract_list return size_t instead of int
- nativeglue.h: rename "setjmp" entry to "setjmp_" to avoid any clash
- py.mk: use additional CFLAGS to compile string0.c
- modmath: work around msvc float bugs in atan2, fmod and modf
- ringbuf: fix compilation with msvc
- modsys: use consistent naming pattern for module-level const objects
- modbuiltins: fix getattr to work with class raising AttributeError
- dynruntime.h: make mp_obj_str_get_str raise if arg not a str/bytes
- objtype: add __dict__ attribute for class objects
- objtype: use mp_obj_dict_copy() for creating obj.__dict__ attribute
- obj.h: clarify comments about mp_map_t is_fixed and is_ordered
- compile: convert scope test to SCOPE_IS_COMP_LIKE macro
- compile: implement PEP 572, assignment expressions with := operator
- grammar.h: consolidate duplicate sub-rules for :test and =test
- compile: implement PEP 526, syntax for variable annotations
- misc.h: add missing semi-colon in mp_float_union_t for big-endian
- obj.h: add public mp_obj_is_dict_or_ordereddict() helper macro
- objtype: support passing in an OrderedDict to type() as the locals
- asm: add funcs/macros to emit machine code for logical-shift-right
- asm: add condition codes for signed comparisons
- emitnative: implement binary operations for viper uint operands
- objcomplex: add mp_obj_get_complex_maybe for use in complex bin-op
- obj.h: make existing MP_TYPE_FLAG_xxx macros sequential
- rework mp_convert_member_lookup to properly handle built-ins
- obj.h: fix mp_seq_replace_slice_no_grow to use memmove not memcpy
- compile: don't await __aiter__ special method in async-for
- persistentcode: maintain root ptr list of imported native .mpy code
- runtime: fix builtin compile() in "single" mode so it prints exprs
- mphal.h: introduce mp_hal_time_ns and implement on various ports

extmod:
- uzlib: explicitly cast ptr-diff-expr to unsigned
- fix modbluetooth and modwebrepl to build in nanbox mode
- modbluetooth: fix func prototype, empty args should be (void)
- vfs_posix: release GIL during system calls
- modbluetooth: implement config getter for BLE rxbuf size
- modbluetooth.h: fix typo in comment about registering services
- modbluetooth_nimble: fix wrong offset used for descriptor flags
- modframebuf: allow blit source to be a subclass of FrameBuffer
- modbluetooth_nimble: move nimble specific code, factor nimble.mk
- modbluetooth: extract out gatts_db functionality from nimble
- btstack: add empty modbluetooth implementation
- btstack: implement advertising
- btstack: implement service registration
- btstack: implement gatts_db for btstack
- btstack: implement scan and gatt client, connect and disconnect
- btstack: implement notifications/indications for GATT clients
- nimble: clarify active state and check for active in all methods
- modbluetooth: unify error handling in remaining places
- modbluetooth: change scan result's "connectable" to "adv_type"
- nimble: when getting BLE MAC try public address if random fails
- vfs: factor out vfs mount-and-chdir helper from stm32
- modlwip: fix polling of UDP socket so it doesn't return HUP
- modlwip: properly handle non-blocking and timeout on UDP recv
- vfs_posix_file: lock GIL when writing and allow stdio flush
- vfs_posix_file: include unistd.h to get STD{IN,OUT,ERR}_FILENO
- uasyncio: add new implementation of uasyncio module
- uasyncio: add optional implementation of core uasyncio in C
- uasyncio: add manifest.py for freezing uasyncio Py files
- uasyncio: don't create a Loop instance in get_event_loop()
- uasyncio: implement Loop.stop() to stop the event loop
- uasyncio: add error message to Lock.release's RuntimeError
- uasyncio: add StreamReader/StreamWriter as aliases of Stream cls
- uasyncio: add global exception handling methods
- modubinascii: make code private and module self-contained
- btstack: pass through SCAN_RSP events
- modbluetooth: provide FLAG_WRITE_NO_RESPONSE for characteristics
- uasyncio: add Loop.new_event_loop method
- uasyncio: change cannot to can't in error message, and test exp
- nimble: update to work with NimBLE 1.3
- modbluetooth: don't hold atomic section during mp_sched_schedule
- btstack: implement more robust init/deinit sequencing
- modbluetooth: fix sign compare and unused variable warnings
- modbtree: retain reference to underlying stream so it's not GC'd
- vfs_lfsx: fix path handling in uos.stat() to consider cur dir
- vfs_lfsx: normalize path name in chdir
- vfs_lfsx: fix rename to respect cur dir for new path
- modbluetooth: add support for changing the GAP device name
- nimble: make error code mapping default to MP_EIO
- vfs_lfsx: fix import_stat so it takes into account current dir
- vfs: retain previous working directory if chdir fails
- modbluetooth: make modbluetooth event not a bitfield
- modbluetooth: add discover complete events for svc/char/desc
- modbluetooth: allow discovery of svc/char by uuid
- modbluetooth: implement read done event
- modbluetooth: ensure status=0 always on success
- modbluetooth: support bigger characteristic values
- ure: use single function for match/search/sub
- uasyncio: add asyncio.wait_for_ms function
- modbluetooth: register default GATT service and fix esp32 init
- moductypes: use mp_obj_is_dict_or_ordereddict to simplify code
- vfs_lfs: fix littlefs bindings to build in nan-box mode
- nimble: fix attr NULL ptr dereference in ble_gatt_attr_read_cb
- btstack: schedule notify/indicate/write ops for bg completion
- modbluetooth: ignore unused self_in in ble_gatts_indicate
- modbluetooth: fix so it builds in peripheral-only mode
- modbluetooth: add event for "indicate acknowledgement"
- modussl: improve exception error messages
- modussl_mbedtls: integrate shorter error strings
- uasyncio: add StreamReader.readexactly(n) method
- vfs_reader: fix mp_reader_new_file to open file in "rb" mode
- uasyncio: truncate negative sleeps to 0
- vfs_lfs: add mtime support to littlefs files
- btstack: implement GAP scan duration_ms parameter
- modbluetooth: fix race between READ_REQUEST and other IRQs
- bluetooth: support active scanning in BLE.gap_scan()
- machine_i2c: fix buffer overrun if 'addrsize' is bigger than 32
- modlwip: fix error return for TCP recv when not connected
- vfs: support larger integer range in VFS stat time fields
- vfs: add option to use 1970 as Epoch

lib:
- utils/pyexec: introduce MICROPY_REPL_INFO, wrap debug prints in it
- mp-readline: add an assert() to catch buffer overflows
- mp-readline: add word-based move/delete EMACS key sequences
- utils: change default value of pyexec_mode_kind to 0 to put in bss
- utils/pyexec: handle pending exceptions after disabling kbd intrs
- add BlueKitchen BTstack submodule
- tinyusb: update to a6b916ba for i.MX support
- btstack: update to latest master btstack commit
- littlefs: update littlefs2 to v2.2.0
- mynewt-nimble: update submodule to NimBLE release 1.3.0
- btstack: update to c8b9823 for USB HCI reset timeout fix
- nrfx: upgrade to nrfx v2.0.0
- utils: lock the scheduler when executing hard callback functions
- utils/pyexec: add missing MP_ERROR_TEXT when compiler disabled
- utils: protect all of mpirq.c with MICROPY_ENABLE_SCHEDULER
- libc: add implementation of strncpy
- mbedtls_errors: add code to patch mbedtls for shortened error strs
- stm32lib: update library for H7 v1.6.0 and WB v1.6.0
- libm_dbl: add round.c source code
- libc: fix string0's implementation of strncpy
- timeutils: add helper functions to deal with nanosecs since 1970

drivers:
- cyw43: fix to build in nanbox mode
- cyw43: include stdio.h in files that use printf
- cyw43: return early from cyw43_wifi_set_up if wifi_on fails
- nrf24l01: change pipe addrs in test to match Arduino addrs
- onewire: fix undefined variable errors
- display/ssd1306.py: change the SET_COM_PIN_CFG setting
- support SPI/QSPI flash chips over 16MB

mpy-cross:
- main: fix stderr_print_strn parameter type
- main: print uncaught nlr jump to stderr

Support components
==================

docs:
- more consistent capitalization and use of articles in headings
- library/machine.I2C.rst: use positional-only arguments syntax
- library/machine.UART.rst: detail timeout behaviour of read methods
- README: add short paragraph about using readthedocs
- library/machine: document machine.soft_reset() function
- library: add / to indicate positional-only args in library docs
- library/uos.rst: improve block devices section, and ioctl ret vals
- esp8266: in TCP tutorial, add HTTP response code and content-type
- unix: add a new new quickref page for the UNIX port
- library: fix framebuf monochrome 1-bit modes, swapping HLSB/HMSB
- develop: detail how to add symbols to mp_fun_table for native mods
- library: add initial docs for uasyncio module
- add docs and test for uasyncio custom exc handler methods
- library: note that uasyncio.wait_for() can raise exception
- library: document that char_data/notify_data are also references
- library: note that machine.Pin.irq's hard arg may not be supported
- library: fix docs for machine.WDT to specify millisecond timeout
- develop: fix module/source name in Makefile of native example
- reference: add note about multiple exceptions when heap is locked
- library: update ubluetooth for new events and discover by uuid
- fix Sphinx 3.x warnings, and enable warnings-as-errors on build
- esp8266: add quickref documentation for UART on esp8266
- library: clarify that the arg to esp.deepsleep is in microseconds
- esp32: add info about PWM duty cycle range to esp32 quickref
- library: add gatts_indicate() doc to ubluetooth.rst
- library: for ubluetooth, add docs for _IRQ_GATTS_INDICATE_DONE
- library: update documentation of esp32's RMT
- library: update pyb.SPI init method to add descr about "ti" arg
- library: update pyb.Timer to add missing args and defaults to init
- library: update pyb.UART to correct pyboard UART availability
- esp32: fix machine.Timer quickref to specify HW timers
- change `\*` to `*` in argument lists

examples:
- accellog.py: shift long comments to their own line
- bluetooth/ble_temperature_central.py: shorten comment
- natmod: add .gitignore to ignore generated example .mpy files
- bluetooth: replace "connectable" parameter with "adv_type"
- bluetooth: fix incorrect value of BR/EDR flag in advertising
- bluetooth: fix event code in ble_temperature_central.py
- bluetooth: in ble_advertising.py, skip appearance if not set
- bluetooth: add simple UART demo with central and peripheral

tests:
- run-tests: add "--mpy-cross-flags" arg to specify mpy-cross flags
- extmod: split out VfsFat finaliser tests to separate test file
- micropython: add test for yield-from while heap is locked
- run-tests: handle 'CRASH' return by float.py feature test
- cpydiff: add CPy diff-test for using dict.keys() as a set
- unix: make unix time test pass on more platforms
- unix: add coverage test for new mp_obj_int_get_uint_checked func
- make run-tests help and README be more descriptive of behaviour
- extmod: add basic machine.Timer test
- unix: add coverage tests for pairheap data structure
- unix: add coverage test for mp_obj_new_exception_args
- unix: add coverage tests for mp_obj_is_type() and variants
- add boolean-as-integer formatting tests for fixed regression
- add tests for generator throw and yield-from with exc handlers
- basics: expand test cases for equality of subclasses
- cmdline/repl_inspect: add new test for -i option
- cmdline: add test for MICROPYINSPECT environment variable
- cpydiff: add os module environ differences
- move CPy diff test to real test now that subclass equality works
- basics: move test for "return" outside function to own file
- unix: add coverage tests for kbd-intr and scheduler
- run-tests: auto-skip extmod/ticks_diff, extmod/time_ms_us tests
- basics: add tests for equality between bool and int/float/complex
- basics: add test for equality between tuple and namedtuple
- basics: add test for tuple compare with class derived from tuple
- basics/array1.py: add equality testing for array
- run-multitests.py: add new test runner for multiple Py instances
- multi_net: add initial set of multi-instance tests for network
- multi_bluetooth: add initial tests for bluetooth BLE
- run-tests: consider all tests as native when emit=native is used
- run-multitests.py: print test summary and do exit(1) on failure
- extmod: add uasyncio tests
- run-tests: skip uasyncio if no async, and skip one test on native
- make default MICROPYPATH include extmod to find uasyncio
- multi_net: add uasyncio test for TCP server and client
- net_inet: add uasyncio internet tests
- basics/dict_pop.py: remove extra comma in call and fix grammar
- micropython/heapalloc_fail_set.py: remove extra trailing comma
- format all Python code with black, except tests in basics subdir
- float: add new lexer test to test parsing of float without prefix
- run-tests: add commands to print and clean *.exp,out files
- extmod: update littlefs test output to match new library version
- run-tests: make diff tool user configurable
- float: fix cmath_fun_special for MICROPY_FLOAT_IMPL_FLOAT
- extmod: add btree test for errors raised by btree DB library
- run-multitests.py: allow filtering out lines from stdout
- multi_bluetooth/ble_gap_advertise: fix bytes/str compare warning
- run-multitests.py: add shortcuts for local Python instances
- cpydiff: add cpydiff test for __all__ used in imported package
- thread/thread_stacksize1.py: increase stack size for CPython
- multi_bluetooth: fix typo printing wrong IRQ type
- run-multitests.py: add TRACE banner and move TEST output to end
- run-tests: skip REPL feature checks when running via pyboard.py
- multi_bluetooth: update to work with new BLE events
- run-multitests.py: allow passing unique env vars to each instance
- basics: add tests for assignment operator :=
- cpydiff: add CPy diff test for assignment expression behaviour
- basics: add tests for variable annotations
- basics: split out memoryview slice-assign tests to separate file
- move .mpy import tests from import/ to micropython/ dir
- micropython: improve .mpy import tests to run on more targets
- extmod: add test for uasyncio.sleep of a negative time
- extmod: make uasyncio_fair test more reliable by adjusting sleeps
- run-tests: use absolute paths where possible
- run-tests: make test output directory configurable
- split out complex reverse-op tests to separate test file
- extmod: add tests for verifying FAT and littlefs mtime values

tools:
- gen-cpydiff.py: adjust subsections to sentence case
- add metrics.py script to build and compute port sizes/metrics
- pydfu.py: clean up syntax, update comments and docstrings
- pyboard.py: add option --no-follow to detach after sending script
- pyboard.py: use slice del instead of list.clear() for Py2 compat
- pyboard.py: change shebang to use python3
- makemanifest.py: support freezing with empty list of mpy files
- codeformat.py: add formatter using uncrustify for C, black for Py
- makemanifest.py: fix build on Windows by adding .exe to mpy-cross
- metrics.py: use check_call instead of run to error out on error
- codeformat.py: eliminate need for sizeof fixup
- pydfu.py: add args for VID/PID & exit with cleaner error handling
- pydfu.py: display any error strings from device/mboot
- codeformat.py: include all msvc C code in auto-format
- pyboard.py: support setting device/baudrate from shell env vars
- pyboard.py: add -d as an alias for --device
- metrics.py: add option to diff to error if delta above threshold
- metrics.py: don't build mpy-cross if not needed by any ports
- metrics.py: use OrderedDict when reading build log
- check_code_size.sh: remove unused script
- codeformat.py: use -q option on uncrustify to make output quiet
- codeformat.py: add verbose option to pass to uncrustify and black
- uncrustify.cfg: remove deprecated sp_word_brace option
- codeformat.py: remove sizeof fixup
- uncrustify: update config for v0.71.0
- codeformat.py: include extmod/{btstack,nimble} in code formatting
- uncrustify: enable more opts to remove space between func and '('
- makemanifest.py: support freezing a subdirectory recursively
- pydfu.py: respect longer timeouts requested by DFU device/mboot
- makemanifest.py: use errno.EEXIST instead of number 17
- makemanifest.py: print nicely formatted errors from mpy-cross
- pyboard.py: replace eval() of received data with alternative
- mpy-tool.py: fix offset of line number info
- makemanifest.py: use os.makedirs to make path for generated files

CI:
- add new job to build and test unix coverage in 32-bit mode
- add stm32 build in nanbox mode
- update travis to specify which unix variant to build
- add OSX build to CI
- add CI job to check code formatting
- build stm32 PYBD_SF6 with BTstack as bluetooth stack
- run multi_net tests as part of coverage job
- for unix tests use Makefile target instead of explicit commands
- print errors out for OSX job
- exclude some uasyncio tests on OSX
- use custom PPA to get pre-built uncrustify
- use grep with --text on qemu-arm output
- build NUCLEO_L073RZ instead of B_L072Z_LRWAN1 for stm32 job
- build full unix coverage build on osx job
- build GENERIC_1M board as part of esp8266 job
- make OSX build work again by not installing pkgconfig
- split esp32 ESP-IDF v3 and v4 builds to separate jobs
- decrease build duration by starting OSX build early
- finish jobs early after test failure
- use tools/metrics.py to compute size diff of minimal ports
- make sure upstream/master exists when computing size-diff check
- build more boards as part of nrf job
- run apt commands once, to slightly speed up the CI
- set build name so it appears in the web interfaces
- for powerpc job, build both UART variants
- change nrf pca10056 board to build with soft-device enabled
- build qemu-arm with MP_ENDIANNESS_BIG=1 to test bigendian build
- in stm32 job, build mboot for NUCLEO_WB55
- build mboot for PYBV10 with LFS2 enabled in stm32 job
- install newer toolchain for nrf job
- add pca10090 build to nrf job
- change nrf pca10056 board to build with s140 SoftDevice
- add zephyr build to CI
- add GitHub action to build docs

The ports
=========

all ports:
- allow overriding CROSS_COMPILE in a custom makefile
- modify mp_hal_pin_write macro so it can be used as a function
- add lib/libm/roundf.c to bare-metal Makefile's
- enable error text compression for various ports, but not all
- disable MICROPY_PY_ASSIGN_EXPR in bare-arm and minimal ports

cc3200 port: no changes specific to this port

esp8266 port:
- modules: fix AttributeError in _boot.py if flash not formatted
- modules/ntptime.py: add comment about configuring NTP host
- put mp_keyboard_interrupt in IRAM
- machine_pin: disable ets_loop_iter during hard IRQ handler
- modmachine: implement machine.soft_reset()
- README.md: add docker build instructions
- modnetwork: add support for wlan.ifconfig('dhcp')
- enable and freeze uasyncio
- change from FAT to littlefs v2 as default filesystem
- makeimg.py: print out info about RAM segments when building fw
- machine_pin: move pin_intr_handler to iRAM, de-support hard IRQ
- mpconfigport.h: add definitions for BEGIN/END_ATOMIC_SECTION
- clean up Pin intr handler by moving all code to machine_pin.c
- boards: move py/pairheap.c code from iRAM to iROM
- esp_mphal: move most functions in esp_mphal.c from iRAM to iROM
- uart: move a few functions from iRAM to iROM
- boards: allow configuring btree/FAT/LFS2 support when building
- esppwm: fix PWM glitch when setting duty on different channel

esp32 port:
- Makefile: assign result of $call to dummy var for older make
- modmachine: add implementation of machine.soft_reset()
- enable NimBLE support on all builds (IDF 3.3 and 4.0)
- modnetwork: add max_clients kw-arg to WLAN.config for AP setting
- Makefile: reorder includes to build with latest toolchain
- uart: use core-provided mp_keyboard_interrupt, placed in IRAM
- modsocket: convert EADDRINUSE error code from lwip return value
- move to IDF 4.0 release version
- deinitialize Bluetooth on soft reset
- README.md: update build instructions for newer toolchain
- modsocket: handle poll of a closed socket
- enable and freeze uasyncio
- README.md: fix typo in venv instructions
- change from FAT to littlefs v2 as default filesystem
- espneopixel: use integer arithmetic to compute timing values
- update to ESP IDF v3.3.2
- modesp32: add idf_heap_info(capabilities) to esp32 module
- consolidate check_esp_err functions and add IDF error string
- improve support for OTA updates
- partitions: update comments in files regarding offset
- modsocket: fix getaddrinfo to raise on error
- machine_sdcard: add "freq" keyword arg to SDCard constructor
- modmachine: fix machine.reset_cause to use IDF's esp_reset_reason
- mpthreadport: fix calculation of thread stack size
- update IDF v4.0 supported hash to v4.0.1
- esp32_rmt: extend RMT to support carrier feature
- esp32_rmt: call rmt_driver_install before rmt_config
- esp32_rmt: properly fix looping behaviour of RMT
- network_lan: add support for IP101 PHY
- mphalport: fix mp_hal_time_ns offset

javascript port: no changes specific to this port

mimxrt port:
- add new, minimal port to NXP i.MX RT series CPUs
- add MIMXRT1010 board
- add MIMXRT1060_EVK board
- add initial impl of machine.LED class, and basic pin support
- tusb_config.h: preliminary fix for TinyUSB HS endpoint overflow
- boards: enable LED class for MIMXRT1060_EVK board
- boards: integrate support for MIMXRT1020_EVK board
- boards: set __heap_size__ to 0 in MIMXRT1011.ld

minimal port:
- make build more flexible and work as 64-bit build

nrf port:
- main: remove unnecessary repl_info(0) call
- boards/common.ld: add ENTRY(Reset_Handler) in linker script
- drivers: use mp_raise_msg where appropriate, and shorten exc msgs
- drivers/bluetooth: fix variable initialisation error with older gcc
- remove custom "random" module and use extmod version instead
- use MICROPY_HW_ENABLE_RNG instead of MICROPY_PY_RANDOM_HW_RNG
- Makefile: don't use -fno-builtin for Cortex-M0 builds
- mphalport: remove need for "syntax unified" in mp_hal_delay_us
- update to work with nrfx v2.0.0, to match TinyUSB
- add openocd as a supported flasher
- bluetooth: use MP_ERROR_TEXT for all error messages
- bluetooth/ble_uart: fix implicit declaration of function
- bluetooth: handle data length update request
- bluetooth/ble_uart: add mp_hal_stdio_poll function
- bluetooth/ble_uart: fix random advertisement name
- bluetooth/ble_uart: swap end character on cooked strings
- Makefile: disable ROM text compression when compiling for debug
- add support for time.ticks_xxx functions using RTC1
- enable nrf tick support on all boards by default
- boards: add initial support for Actinius Icarus
- nrfx_config: disable RTC2 for nRF9160 targets
- boards: enable RTCounter machine module for nrf9160 boards
- add board definition for nRF52840-MDK-USB-Dongle
- split mpconfigport.h into multiple files
- enable more features for all targets
- Makefile: improve user C modules support

pic16bit port: no changes specific to this port

powerpc port:
- fix Makefile rule when linking
- set better default compiler
- uart: choose which UART to use at build time, not runtime

qemu-arm port:
- set default board as mps2-an385 to get more flash for tests
- README: update link to toolchain
- support building in debug mode with DEBUG=1
- Makefile: add CFLAGS_EXTRA to CFLAGS

samd port:
- fix to build with latest tinyusb

stm32 port:
- mbedtls: resize mbedtls output buffer from 16 down to 4 kiB
- fix to build in nanbox mode
- add configuration to build in nanbox mode
- boards/PYBD: change RTC asynch prediv from 1 to 4
- softtimer: change linear linked list to a pairing heap
- powerctrl: for F7, allow PLLM!=HSE when setting PLLSAI to 48MHz
- Makefile: allow a board's .mk file to add things to CFLAGS
- boards/STM32F769DISC: add config to use external SPI as filesys
- powerctrl: disable HSI if not needed to save a bit of power
- powerctrl: enable overdrive on F7 when waking from stop mode
- boards/stm32f746_af.csv: add ADC alt functions to correct pins
- sdio: add support for H7 MCUs
- stm32_it: don't call __HAL_USB_HS_EXTI_CLEAR_FLAG on H7 MCUs
- powerctrl: improve support for changing system freq on H7 MCUs
- powerctrl: reenable PLL3 on H7 MCUs when waking from stop mode
- sdram: expose the result of sdram startup test in stm32_main
- usbd_conf: allow boards to configure USB HS ULPI NXT/DIR pins
- usbd_cdc_interface: remove "interrupt_char != -1" check
- sdram: fix compile issue from unused sdram startup test flag
- mpconfigport.h: add option to have custom help text
- modnetwork: remove redundant call to nimble_poll in lwip poll
- refactor bluetooth stack/hci/driver bindings
- add bindings for BTstack implementation
- boards/PYBD: allow building with BTstack (via make command line)
- refactor Bluetooth HCI RX to be independent of transport layer
- main: fix bug mounting 3rd SD partition
- mboot: allow overriding led_init and led_state in board folder
- mboot: update dfu state/status flags to better match standard
- mboot: protect against invalid address flash writes
- mboot: update LED0 state from systick handler
- mboot: remove unnecessary test for led being 1 in led_state
- softtimer: initialise pairing-heap node before pushing to heap
- enable and freeze uasyncio
- mpconfigport.h: remove unused root pointer for BTstack bindings
- mpconfigport.h: make most extended modules configurable by board
- boards: disable pend_throw, uheapq, utimeq on small-flash boards
- Makefile: add missing ordering dependency on generated headers
- storage: fix start address of second, internal block device
- mboot/README: clarify that mboot can access FAT formatted FS only
- mboot: expose custom DFU USB VID/PID values at makefile level
- Makefile: rename SRC_LIB to LIB_SRC_C to match other ports
- main: peform a clean shutdown of btstack on soft reset
- boards/PYBD_SF2: put BTstack library in external QSPI XIP flash
- README: reorg DFU flashing instructions with addition for PYBD
- add support for F412 MCUs
- boards: add board config for Nucleo-F412ZG development board
- machine_uart: retain attached-to-repl setting when init'ing UART
- machine_uart: allow re-init'ing a static UART object
- modmachine: allow changing AHB and APB bus frequencies on STM32WB
- adc: add support to pyb.ADC for STM32WB MCUs
- machine_adc: make setting of ADC1_COMMON->CCR clearer on STM32WB
- dma: add support for DMA on STM32WB, with SPI settings provided
- boards/xxx_WB55: enable pyb.ADC and hardware SPI on WB55 boards
- Makefile: quote libgcc path so spaces are not an issue
- boards/STM32F769DISC: use macro instead of const for flash size
- factoryreset: provide empty create-FS function when FAT disabled
- usb: add support for 2xVCP on L0, L432 and WB MCUs
- rfcore: leave txpower level as default when initialising rfcore
- boards/NUCLEO_WB55: add more CPU pins and aliases to SW1/2/3
- irq: clean up irq.h so it does not depend on core uPy defines
- powerctrlboot: include irq.h to get definitions of IRQ priorities
- flash: make flash C-API reusable, and funcs return an error code
- i2cslave: add support for WB MCUs
- flash: add flash_is_valid_addr, and extend sectors for 2MB F7
- mboot: use flash routines from main stm32 code rather than custom
- mboot: use CMSIS system source code for SystemInit function
- mboot: add support for using mboot with WB MCUs
- boards: add build-time option for NUCLEO_WB55 to use mboot
- mboot: set VTOR on start up to ensure it has the correct value
- mboot: use additional CFLAGS to compile string0.c
- mpconfigport.h: enable PY_IO_FILEIO when any VFS is enabled
- timer: support TIM1 on WB MCUs
- boards: enable LFS2 on PYBD_SF3 and PYBD_SF6
- mboot: don't search for firmware on FS, just attempt to open it
- mboot: decouple stream, filesystem and top-level loading code
- mboot: add support for littlefs
- mboot: update README to describe WB and littlefs support
- i2cslave: pass I2C instance to callbacks to support multi I2Cs
- usbd_cdc_interface: remove full==size-1 limitation on tx ringbuf
- timer: properly initialise timer deadtime/brk on WB MCUs
- mboot: implement DFU mass erase
- flash: update flash_get_sector_info to return -1 on invalid addr
- mboot: add DFU logic to respond to DFU_GETSTATE request
- mboot: remove the use of timeout in DFU_GETSTATUS
- mboot: disable polling mode by default and use IRQ mode instead
- fdcan: use the right FIFO to calc element address in can_receive
- fdcan: use FDCAN_RXFxS_FxFL instead of hard-coded value
- fdcan: support maximum timeout of HAL_MAX_DELAY in can_receive
- pyb_can: handle timeout arg for FDCAN in pyb_can_send
- usbdev: fix calculation of SCSI LUN size with multiple LUNs
- pin_defs_stm32: fix pin printing to show IN mode correctly
- powerctrl.h: include stdbool.h to get definition of bool

teensy port: no changes specific to this port

unix port:
- modtime: add utime.mktime function, to complement utime.localtime
- modos: add uos.rename and uos.rmdir
- add build variants, analogous to boards on bare-metal
- add placeholder DEV variant with settrace enabled
- rename unix binaries to micropython-variant (not _variant)
- Makefile: reserve CFLAGS_EXTRA/LDFLAGS_EXTRA for external use
- release GIL during all system calls
- unix_mphal: add compile check for incompatible GIL+ASYNC_KBD_INTR
- main: print usage and NLR errors to stderr instead of stdout
- main: add support for MICROPYINSPECT environment variable
- main: add #if guard around -v option usage and document -i/-m opts
- main: add command-line -h option for printing help text
- modos: implement putenv and unsetenv to complement getenv
- main: use OS-dependent path separator when searching path
- Makefile: remove old variant targets that are no longer needed
- variants/standard: fix role of PREFIX when used to install
- Makefile: allow to install all variants of the executable
- mpthreadport: use SIGRTMIN+5 instead of SIGUSR1 for thread-GC
- mpthreadport: fix Mac build by using SIGUSR1 if SIGRTMIN not avail
- mphalport.h: fix build when MICROPY_USE_READLINE=0
- unix_mphal: adjust #if in mp_hal_stdin_rx_chr to improve format
- file: don't raise OSError(EINVAL) on sys.stdin/out/err.flush()
- Makefile: detect and pass thru mpy-cross flags when running tests
- remove custom file implementation to use extmod's VFS POSIX one
- remove custom definition of MP_PLAT_PRINT_STRN
- coverage: init all pairheap test nodes before using them
- enable uasyncio C helper module on coverage build
- mpthreadport: fix crash when thread stack size <= 8k
- implement PEP 475 to retry syscalls failing with EINTR
- mpthreadport: ensure enough thread stack to detect overflow
- fix behaviour of COPT/NDEBUG for unix variants
- implement MICROPY_BEGIN/END_ATOMIC_SECTION protection macros
- Makefile: fix regression using install on non-GNU systems
- modmachine: add machine.idle(), implemented using sched_yield
- add support for modbluetooth and BLE using btstack
- enable modbluetooth on the "dev" and "coverage" variants
- add btstack to the unix submodules list
- main: enter REPL when inspect active, even with stdin redirected
- btstack_usb: allow choosing adaptor via environment variable
- make manifest selection match other ports
- enable uasyncio on dev variant
- variants: enable VFS and all supported filesystems on dev variant
- make the MICROPY_xxx_ATOMIC_SECTION mutex recursive
- fatfs_port: implement get_fattime
- variants: fix fast and freedos variants so they build again
- modos: support larger integer range in uos.stat fields

windows port:
- support word-based move/delete key sequences for REPL
- windows_mphal: release GIL during system calls
- improve default search path
- msvc: fix warnings regarding function declarations
- remove custom definition of MP_PLAT_PRINT_STRN
- windows_mphal: fix missing semicolon
- update genhdr.targets to match makeqstrdefs.py args
- make appveyor.yml self-contained

zephyr port:
- update include paths for Zephyr v2.0
- replace deprecated time conversion macro
- remove reference to syscall_macros_h_target
- implement block device protocol via zephyr disk access api
- enable virtual file system and uos module
- enable fatfs
- implement block device protocol via zephyr flash map api
- enable littlefs
- mount a file system during init
- enable usb mass storage class on mimxrt1050_evk
- execute main.py file if it exists
- update machine.Pin class to use new zephyr gpio api
- use zephyr build system to merge configurations
- fix and rename stacks_analyze function in zephyr module
- fix floating point configuration
- update for refactored zephyr device structures
- update to new zephyr timeout API
- convert DT_FLASH_AREA usages to new dts macros
- increase minimum required cmake version to 3.13.1
- use cmake find_package to locate zephyr
- implement machine.Pin.irq() for setting callbacks on pin change
- make-minimal: disable FAT and LFS2 options to make it build
- include storage/flash_map.h unconditionally
- README: update required Zephyr version and mention new features

PYBD boards, BLE and littlefs, dynamic native modules, samd and powerpc

This release sees a reduction in overall bytecode size due to compression
of the bytecode prelude, saving 7 bytes of bytecode per function for
roughly 80% of functions.  The bytecode opcode values are also redefined to
group them based on their argument size and format.  Support is also added
for the matrix multiplication operator "@" (PEP 465).

The .mpy file format moved to version 5 to support the new bytecode
encoding, and added support for relocation of native machine code, along
with separate rodata and BSS sections.  This allows a MicroPython system to
import dynamic native modules, .mpy files that are generated from C code.
Examples of this feature are provided in "examples/natmod/" and
documentation in "docs/develop/natmod.rst".

Some code-size saving optimisations were implemented leading to a reduction
in size of minimal firmware: bare-arm reduced by 584 bytes, minimal x86 by
5476 bytes (partly due to changed compiler optimisation flags) and minimal
ARM Thumb 2 by 1440 bytes (all measured with gcc 9.2.0).

A new mechanism to freeze scripts into firmware is provided - a frozen
manifest - whereby scripts to freeze are listed in a Python file (eg
manifest.py).  All ports are updated to use this new feature.

When weak module links are enabled (via MICROPY_MODULE_WEAK_LINKS) an
import will now automatically search for the built-in u-variant of a module
if the non-u-variant fails (eg searches for "ufoo" if "foo" fails), so
ports no longer provide an explicit list of these.  The unix and windows
ports now enable this feature.

A performance benchmarking test suite is added which can be used to compare
changes in absolute performance when optimising features, as well as
compare across different ports.  See "tests/run-perfbench.py".

Bluetooth (BLE only) support is added via the "ubluetooth" module and
provides the ability to implement the four BLE roles.  The BLE stack is
used is Mynewt Nimble and it currently runs on PYBD boards, STM32WB55 MCUs
and ESP32 boards.

Support for littlefs filesystems is added through the MicroPython VFS
interface, and it works on the unix, stm32, esp8266 and esp32 ports.

A new "machine.ADC.read_u16()" method is defined and implemented on stm32,
esp8266, esp32 and nrf ports, providing a consistent way to read an ADC
that returns a value in the range 0-65535.  This new method should be
preferred to the existing "ADC.read()" method.

The stm32 port sees support for the new PYBD range of pyboards which
include a fully integrated CYW43xx WiFi/BT chip.  USB is enhanced to
support VCP+MSC+HID mode and up to 3x simultaneous VCP interfaces.  Support
is also added for STM32WBxx MCUs including BLE.  There is a new machine.ADC
class which is compatible with other ports, along with a new machine.Timer
class that implements a software timer with millisecond resolution and
number of active timers only limited by RAM.  Support for littlefs is
available by default via uos.VfsLfs2.  Documentation for using littlefs is
found in "docs/reference/filesystem.rst".

The esp8266 port has switched to use per-board configurations and builds,
as well as the new frozen manifest feature.  It also has optional littlefs
support (requires a separate build).

The esp32 port has the following new features: native code generation,
machine.SDCard, hardware I2C, mDNS queries and responder, esp32.Partition,
esp32.RMT, BLE (requires IDF v4), and built-in support for VfsLfs2.  It has
switched to use per-board configurations and builds, and frozen manifests.
The default SSL output buffer is resized from 16kiB down to 4kiB to save
RAM.

There are new, minimal ports to Microchip SAMDxx microcontrollers, and
the bare metal PowerPC architecture.

A code-of-conduct based on the PSF's code is added in CODEOFCONDUCT.md.

The following new Git submodules are added: mbedtls, asf4, tinyusb,
mynewt-nimble.  And a new third-party library: littlefs.

A detailed list of changes follows.

py core:
- nativeglue: make private glue funs all static, remove commented code
- nativeglue: remove dependency on mp_fun_table in dyn-compiler mode
- obj: optimise small-int comparison to 0 in mp_obj_is_true
- nlrthumb: save and restore VFP registers s16-s21 when CPU has them
- mkrules.mk: use $(CPP) not $(CC) -E for preprocessor rule
- define EMIT_MACHINE_CODE as EMIT_NATIVE || EMIT_INLINE_ASM
- persistentcode: fix compilation with load and save both enabled
- persistentcode: ensure prelude_offset is always initialised
- asmarm: use __clear_cache on Linux/GCC when creating new asm code
- nlrthumb: check __thumb2__ instead of __ARM_ARCH_6M__
- objgenerator: add missing #if guard for PY_GENERATOR_PEND_THROW
- asmarm: use __builtin___clear_cache instead of __clear_cache
- makeqstrdata.py: allow using \r\n as a qstr if a port requires it
- scheduler: rename sched_stack to sched_queue
- objstringio: guard bytesio_stream_p struct w/ MICROPY_PY_IO_BYTESIO
- objdict: quote non-string types when used as keys in JSON output
- builtinimport: populate __file__ when importing frozen or mpy files
- runtime: allow to override builtins.__import__ with Python func
- modio: call mp_import_name to do resource stream import
- allow to pass in read-only buffers to viper and inline-asm funcs
- showbc: fix off-by-one when showing address of unknown opcode
- implement new sys.atexit feature
- objarray: fix amount of free space in array when doing slice assign
- modmath: implement math.isclose() for non-complex numbers
- introduce MP_UNREACHABLE macro to annotate unreachable code
- nlr: use MP_UNREACHABLE at the end of arch-specific nlr_jump funcs
- compile: improve the line numbering precision for comprehensions
- emitbc: rewrite switch in load_const_tok to reduce code size
- emitbc: make all emit_write_bytecode_* funcs take a stack_adj arg
- objgenerator: move defn of mp_const_GeneratorExit_obj here
- vm: shorten error message for not-implemented opcode
- vm: don't add traceback info for exc's propagated through a finally
- vm: don't add traceback info for exceptions that are re-raised
- add global default_emit_opt variable to make emit kind persistent
- compile: improve the line numbering precision for lambdas
- bc: factor out code to get bytecode line number info into new func
- profile: add initial implementation of sys.settrace feature
- integrate sys.settrace feature into the VM and runtime
- profile: add debugging for sys.settrace feature
- objtuple: allow compatible subclasses of tuple in mp_obj_tuple_get
- modstruct: fix struct.unpack with unaligned offset of native type
- modstruct: fix struct.pack_into with unaligned offset of native type
- binary: change mp_uint_t to size_t for index, size, align args
- bc: fix size calculation of UNWIND_JUMP opcode in mp_opcode_format
- mkenv.mk: add GDB variable
- vm: factor cached map lookup code to inline function
- mkrules.mk: add QSTR_GLOBAL_REQUIREMENTS variable for qstr auto-gen
- persistentcode: enable persistent code saving for Windows ports
- lexer: reorder operator tokens to match corresponding binary ops
- parse: use calculation instead of table to convert token to operator
- compile: use calculation instead of switch to convert token to op
- add support for matmul operator @ as per PEP 465
- bc0: order opcodes into groups based on their size and format
- bc: replace big opcode format table with simple macro
- introduce and use constants for multi-opcode sizes
- split RAISE_VARARGS opcode into 3 separate ones
- nlr.h: factor out constants to specific macros
- emitnative: factor sizeof/offsetof calculations to macros
- rename MP_QSTR_NULL to MP_QSTRnull to avoid intern collisions
- nativeglue: make mp_fun_table fixed size regardless of config
- persistentcode: bump .mpy version to 5
- ringbuf: add helpers for put16/get16
- bc: change mp_code_state_t.exc_sp to exc_sp_idx
- add n_state to mp_code_state_t struct
- compress first part of bytecode prelude
- rework and compress second part of bytecode prelude
- bc: don't include mp_decode_uint funcs when not needed
- compile: disallow 'import *' outside module level
- makeqstrdefs.py: remove unused blacklist
- vm: fix handling of unwind jump out of active finally
- runtime: fix PEP479 behaviour throwing StopIteration into yield from
- emitnative: add support for archs with windowed registers
- emitnative: add support for using setjmp with native emitter
- emitnative: add support for archs that cannot read executable data
- asmxtensa: add support for Xtensa with windowed registers
- add new Xtensa-Windowed arch for native emitter
- persistentcode: make .mpy more compact with qstr directly in prelude
- objtype: add type.__bases__ attribute
- mkrules.mk: add warning/error for invalid frozen config
- objstr: size-optimise failure path for mp_obj_str_get_buffer
- automatically provide weak links from "foo" to "ufoo" module name
- modarray: rename "array" module to "uarray"
- runtime: reorder some binary ops so they don't require conditionals
- stream.h: add MP_STREAM_POLL_NVAL constant
- nativeglue: remove unused mp_obj_new_cell from mp_fun_table
- objgenerator: remove globals from mp_obj_gen_instance_t
- objgenerator: allow pend_throw to an unstarted generator
- persistentcode: move declarations for .mpy header from .c to .h file
- modsys: report .mpy version in sys.implementation
- emitnative: fix typo, REG_PARENT_ARG_RET should be REG_PARENT_RET
- emitnx86: make mp_f_n_args table match order of mp_fun_kind_t
- objdict: support ujson.dump() of OrderedDict objects
- ringbuf: add peek16 method
- compile: coalesce error message for break/continue outside loop
- builtinimport: raise exception on empty module name
- qstr: raise exception in qstr_from_strn if str to intern is too long
- objstringio: slightly optimize stringio_copy_on_write for code size
- objenumerate: check for valid args in enumerate constructor
- persistentcode: add ability to relocate loaded native code
- nativeglue: add new header file with native function table typedef
- nativeglue: add funcs/types to native glue table for dynamic runtime
- persistentcode: make ARM Thumb archs support multiple sub-archs
- nativeglue: add float new/get functions with both single and double
- dynruntime: add support for float API to make/get floats
- dynruntime: implement uint new/get, mp_obj_len and mp_obj_subscr
- persistentcode: move loading of rodata/bss to before obj/raw-code

extmod:
- add network-level class binding to cyw43 driver
- factor out makefile rules from py.mk to new extmod.mk file
- extmod.mk: integrate mbedTLS so it is built from source
- modussl_mbedtls: allow to build with object representation D
- extmod.mk: include mdns app source in lwIP build
- uos_dupterm: add mp_uos_dupterm_poll to poll all dupterms
- moduwebsocket: make close_resp static array const to not use RAM
- modwebrepl: make prompt/ver static arrays const to not use RAM
- modwebrepl: add config option to put filebuf[512] on stack/bss
- modlwip: for TCP send keep trying tcp_write if it returns ERR_MEM
- modlwip: use mp_sched_schedule to schedule socket callbacks
- modlwip: implement raw sockets for lwIP
- modure: make regex dump-code debugging feature optional
- moducryptolib: use "static" not "STATIC" for inline functions
- give vars/funcs unique names so STATIC can be set to nothing
- modujson: support passing bytes/bytearray to json.loads
- crypto-algorithms: add source to header and populate copyright
- vfs_posix: include stdio.h for declaration of function 'rename'
- nimble: add nimble bindings
- modbluetooth: add low-level Python BLE API
- modbluetooth_nimble: implement modbluetooth API with Nimble
- modbluetooth_nimble: use random addr if public isn't available
- modbluetooth: allow MP_BLUETOOTH_MAX_ATTR_SIZE in board config
- modbluetooth: allow config of scan interval/window
- modbluetooth: use us instead of ms for advertising interval
- modbluetooth: increase maximum connections from 1 to 4
- modbluetooth: clear gap_advertise payload when data is empty
- modbluetooth: fix order of params to IRQ_GATTS_WRITE event
- modbluetooth: improve ringbuf handling
- modbluetooth: make gap_disconnect not raise when disconnected
- modbluetooth: in gap_advertise only accept None to stop adv
- re1.5: support escaping within RE classes
- modbluetooth: make UUID support the buffer protocol
- modbluetooth: persist reference to NimBLE service instances
- modbluetooth_nimble: use `data_alloc` length to truncate writes
- modbluetooth: rename module to "ubluetooth"
- factor out block-device struct to make independent of fatfs
- vfs_blockdev: factor out block device interface code
- vfs_blockdev: add extended read/write methods
- add VFS littlefs bindings
- vfs: rename BP_IOCTL_xxx constants to MP_BLOCKDEV_IOCTL_xxx
- vfs: add MP_BLOCKDEV_IOCTL_BLOCK_ERASE constant
- modbluetooth: add gatts_set_buffer
- vfs_lfs: allow compiling in VfsLfs1 and VfsLfs2 separately
- modlwip: unconditionally return POLLHUP when polling new socket
- modlwip: make socket poll return POLLNVAL in case of bad file
- modlwip: unconditionally return POLLHUP/POLLERR when polling
- modussl_mbedtls: fix getpeercert to return None if no cert avail
- modussl_mbedtls: check for invalid key/cert data
- nimble: remove unneeded nimble_sprintf wrapper function
- nimble: factor out stm32-specific HCI UART RX/TX code
- modbtree: make FILEVTABLE const to put it in ROM
- convert nlr_raise(mp_obj_new_exception_msg(x)) to mp_raise_msg(x)
- vfs: add autodetect of littlefs filesystem when mounting
- consolidate FAT FS config to MICROPY_VFS_FAT across all ports
- modbluetooth: prioritise non-scan-result events
- modbluetooth: create UUID from bytes and allow comparison ops
- modbluetooth_nimble: make gap_scan_stop no-op if no scan ongoing
- modbluetooh_nimble: fix UUID conversion for 16 and 32 bit values
- modbluetooth: simplify management of pre-allocated event data
- vfs_lfs: pass flag along to ioctl when init'ing bdev for lfs
- vfs_lfs: fix bug when passing no args to constructor and mkfs
- modbluetooth: simplify how BLE IRQ callback is scheduled
- modbluetooth: remove limit on data coming from gattc data input
- modbluetooth: add optional 4th arg to gattc_write for write mode
- modbluetooth: allow setting ringbuf size via BLE.config(rxbuf=)
- modbtree: use mp_printf instead of printf
- add dynamic-runtime guards to btree/framebuf/uheapq/ure/uzlib
- webrepl: move webrepl scripts to common place and use manifest

lib:
- cmsis: upgrade to CMSIS 5.5.1
- netutils: add DHCP server component
- add new submodule for mbedtls, currently at v2.17.0
- utils/sys_stdio_mphal: add support to poll sys.stdin and sys.stdout
- add asf4 as a submodule
- add tinyusb as a submodule
- stm32lib: update library for updated H7xx, new L0xx, new WBxx
- lwip: update lwIP to v2.1.2, tag STABLE-2_1_2_RELEASE
- mynewt-nimble: add Apache mynewt nimble as a submodule
- littlefs: add littlefs v1.7.2 source
- littlefs: add littlefs v2.1.3 source
- littlefs: add README describing origin and how to gen lfs1/lfs2
- libc/string0: add simple implementations of strspn and strcspn

drivers:
- add driver for CYW43xx WiFi SoCs
- memory/spiflash: add support to put SPI flash in sleep mode
- cyw43: add low-level CYW43xx Bluetooth HCI UART driver
- onewire/ds18x20.py: add support for DS1822 sensor
- sdcard: raise exception on timeout of readinto
- wiznet5k: allow selecting maximum fixed buffer size for MACRAW

tools:
- mpy-tool.py: fix linking qstrs in native code, and multiple files
- mpy-tool.py: fix linking of qstr objects in native ARM Thumb code
- add uf2conv.py from Microsoft/uf2 repository
- pyboard.py: add filesystem commands to ls/cat/cp/rm remote files
- mpy-tool.py: force native func alignment to halfword/word on ARM
- mpy-tool.py: add initial support for frozen with settrace
- mpy-tool.py: fix freezing of non-bytecode funcs with settrace
- make-frozen.py: allow to run with no directory passed in
- add mechanism to provide a manifest of frozen files
- makemanifest.py: eval relative paths w.r.t. current manifest file
- mpy-tool.py: use "@progbits #" attribute for native xtensa code
- makemanifest.py: follow symlinks when freezing linked directories
- makemanifest.py: skip freezing unsupported files with warning
- makemanifest.py: use sys.executable when invoking Python scripts
- mpy-tool.py: support qstr linking when freezing Xtensa native mpy
- mpy-tool.py: add ability to merge multiple .mpy files into one
- mpy_ld.py: add new mpy_ld.py tool and associated build files
- mpy-tool.py: raise exception if trying to freeze relocatable mpy
- pyboard.py: support executing .mpy files directly
- tinytest-codegen.py: add extra newline and result message

tests:
- rename "bench" tests to "internal_bench" and run-internalbench.py
- add performance benchmarking test-suite framework
- perf_bench: add some benchmarks from python-performance
- perf_bench: add some miscellaneous performance benchmarks
- perf_bench: add some viper performance benchmarks
- stress/recursive_iternext.py: increase large depth to 5000
- run-perfbench.py: add --emit option to select emitter for tests
- add tests for overriding builtins.__import__
- misc/sys_atexit: add test for new sys.atexit feature
- unix: update extra_coverage expected output with new atexit func
- extmod: split json.loads of bytes/bytearray into separate test
- split out test for optimisation level and line-no printing
- add tests for sys.settrace feature
- basics: add test for matmul operator
- update tests for changes to opcode ordering
- micropython: add test for native generators
- basics: add test for getting name of func with closed over locals
- basics: add test for throw into yield-from with normal return
- perf_bench: add bm_fft test
- run-perfbench.py: show error when truth check fails
- run-perfbench.py: skip complex tests if target doesn't enable it
- cpydiff: fix typo in types_bytes_keywords.py doc comments
- rename "array" module to "uarray"
- extmod: add littlefs tests
- extmod: add test for blockdev with standard and extended protocol
- basics: use str.format instead of % for formatting messages
- basics/builtin_dir.py: look for "version" in dir(sys)
- add feature check for bytearray and skip corresponding tests
- basics: split out specific bytearray tests to separate files
- basics: use bytes not bytearray when checking user buffer proto
- add feature check for slice and skip corresponding tests
- basics: split out specific slice tests to separate files
- run-tests: add misc list of tests that use slice, to skip them
- basics: automatically skip tests that use str/bytes modulo-format
- add feature check for uio module and skip corresponding tests
- basics: split sys.exit test to separate file so it can be skipped
- extmod: add test for ussl when passing in key/cert params
- stress: add test for maximum length limit of qstrs
- import: add test for importing viper code with additional flags
- add script to run dynamic-native-module tests
- add .exp files for basics/parser and import/import_override
- stress/qstr_limit: tune params to run with stm32 port
- basics/memoryview_itemsize: make portable to 32- and 64-bit archs
- extmod/vfs_lfs_error: use small ints in seek error test
- pyb: refactor pyboard tests to work on PYBv1, PYBLITEv1 and PYBD

mpy-cross:
- do not automatically build mpy-cross, rather do it manually
- main: only accept full emit cmdline options if native enabled
- make mpconfigport.h compatible with msvc compiler
- add msvc build of mpy-cross
- set number of registers in nlr_buf_t based on native arch
- enable Xtensa-Windowed native emitter
- support armv7em, armv7emsp, armv7emdp architectures
- README.md: add notes about -march and -O

all ports:
- provide mp_hal_stdio_poll for sys.stdio polling where needed
- add new make target "submodules" which inits required modules

minimal port:
- use soft float for CROSS=1 Cortex-M4 target
- frozentest: recompile now that mpy version has changed
- set CSUPEROPT=-Os to get minimal firmware size

unix port:
- mpconfigport.mk: update comment about TLS implementations
- unix_mphal: use CLOCK_MONOTONIC for ticks_ms/us when available
- enable sys.atexit, triggered after the main script ends
- main: only accept full emit cmd-line options if native enabled
- coverage: add coverage tests for ringbuf
- convert to use FROZEN_MANIFEST to specify frozen code
- enable module weak links
- enable uos.VfsLfs1, uos.VfsLfs2 on coverage build
- modtermios: fix output speed setter in tcsetattr

windows port:
- mpconfigport.h: define empty MP_WEAK symbol
- mpconfigport.h: don't define restrict/inline/alignof for C++
- msvc: treat compiler warnings as errors
- Makefile: make use of CFLAGS_EXTRA, LDFLAGS_EXTRA and SRC_MOD
- msvc: remove unneeded definitions for qstr generation
- msvc: move build options from .vcxproj to .props files
- msvc: enable overriding directories used in the build
- msvc: change the way sources are listed
- default to binary mode for files
- enable module weak links

qemu-arm port:
- add testing of frozen native modules
- convert to use FROZEN_MANIFEST to specify frozen code
- add ldscript dependency in the final firmware.elf target
- let tinytest.o be built by standard build rules
- Makefile: allow overriding CROSS_COMPILE from another makefile

stm32 port:
- usb: refactor CDC VCP code to enable N CDC interfaces
- usb: support up to 3 VCP interfaces on USB device peripheral
- boards/make-pins.py: allow pins.csv to skip or hide board-pin name
- boards/pllvalues.py: search nested headers for HSx_VALUE defines
- boards: add board definition files for PYBD -SF2, -SF3, -SF6
- modpyb: add pyb.country() function to set the country
- extint: add extint_set() function for internal C access to EXTI
- mphalport: add support for having MAC in OTP region
- add low-level SDIO interface for cyw43 driver
- integrate in the cyw43 driver and network.WLAN class
- boards/PYBD_SFx: enable CYW43 WLAN driver
- modnetwork: replace generic netif NIC polling with specific code
- integrate optional mbedTLS component for ussl module
- boards/PYBD_SFx: enable ussl module using mbedTLS
- support optional lwIP mDNS responder
- lwip_inc: update to enable mDNS, TCP listen backlog, faster DHCP
- usbd_msc: rework USBD MSC code to support multiple logical units
- usbd_msc: provide custom irquiry processing by MSC interface
- usbd_msc: provide Mode Sense response data in MSC interface
- usb: use ARG_xxx enums to access kw args in pyb_usb_mode
- usb: add "msc" kw-arg to pyb.usb_mode to select MSC logical units
- usbd_msc: allow to compile when USB enabled and SD card disabled
- in link script, define start of stack separately from heap end
- boards: enable ussl module via mbedtls for boards with network
- Makefile: print info messages about use of mboot/QSPI flash
- enter bootloader via a system reset
- boards/pllvalues.py: support HSx_VALUE defined without uint32_t
- boards: add stm32??xx_hal_conf_base.h files with common settings
- boards: rework all stm32??xx_hal_conf.h files to use common code
- usb: fix regression with auto USB PID value giving PID=0xffff
- boards: optimise flash and RAM allocation for L4 boards
- mpu: add helper functions for configuring MPU
- eth: use MPU helper functions to configure MPU for ETH use
- sdram: use MPU helper functions to configure MPU for SDRAM use
- qspi: use MPU to allow access to valid memory-mapped QSPI region
- qspi: force a reset of the QSPI peripheral when initialising it
- qspi: handle bus acquisition
- powerctrl: add hooks for a board to perform actions on sleep/wake
- boards/PYBD_SFx: put SPI flash to sleep during sleep modes
- mpconfigport.h: enable useful networking modules if lwIP enabled
- usb: add support to auto-detect USB interface, either FS or HS
- usb: add "port" keyword argument to pyb.usb_mode, to select FS/HS
- spi: factor out code to calculate SPI source frequency
- extint: simplify bitband support config for different MCUs
- modmachine: make RTC class available in machine module
- boards/PYBD_SF2: put mbedtls library code in external QSPI flash
- update components to work with new H7xx HAL
- Makefile: remove Wno-attributes for ll_usb HAL file
- Makefile: use startup_stm32*.s file from stm32lib
- boards: remove startup_stm32*.s files now they are in stm32lib
- mpu: include MPU functions when ETH is enabled
- lwip_inc: define LWIP_NO_CTYPE_H=1 to use lwIP ctype funcs
- modmachine: disable IRQs before entering bootloader
- boards/PYBD_SFx: configure EN_3V3 pin as output on boot
- sdcard: add hook for a board to power on SD/MMC
- boards/PYBD_SFx: automatically turn on EN_3V3 when powering SD/MMC
- add initial support for STM32L0xx MCUs
- boards: add MCU support files for STM32L072
- mpconfigport.h: make "framebuf" module configurable by a board
- boards/NUCLEO_L073RZ: add definition files for new board
- powerctrl: move L0's SystemClock_Config to powerctrlboot.c file
- powerctrl: move F0's SystemClock_Config to powerctrlboot.c
- remove SystemInit funcs, use stm32lib versions instead
- boards/NUCLEO_F446RE: enable DAC
- add support for STM32L452 MCUs
- boards/NUCLEO_L452RE: add definition files for new board
- boards/NUCLEO_F413ZH: remove STARTUP_FILE, it's defined globally
- mboot: make _estack an array to avoid compiler warnings
- mboot: remove use of BSRRL/H for H7 MCUs due to stm32lib update
- mboot: use STARTUP_FILE from stm32lib
- mboot: update dependencies to enable parallel build with -j
- boards/B_L072Z_LRWAN1: add definition files for new board
- gccollect: always use MP_STATE_THREAD(stack_top) to get stack top
- usb: add config options to disable USB MSC and/or HID
- usbd_cdc_interface: make CDC TX/RX buffer sizes configurable
- add support for USB on L0 MCUs
- powerctrlboot: increase SYSCLK to 32MHz for L0 MCUs
- mphalport: fix GPIO clock enable for L0 MCUs
- Makefile: allow a board to disable float support
- boards/B_L072Z_LRWAN1: enable USB VCP support
- boards/STM32F769DISC: fix length of FLASH_APP section
- make-stmconst.py: allow more variation in parens and int-suffix L
- add initial support for STM32WBxx MCUs
- boards: add MCU support files for STM32WB55
- boards/NUCLEO_WB55: add definition files for new board
- boards/USBDONGLE_WB55: add definition files for new board
- flashbdev: support internal filesystem on STM32F722/23/32/33
- boards/stm32f722.ld: provide memory regions for internal FS
- boards/NUCLEO_F722ZE: add definition files for new board
- dma: fix re-start of DMA stream by clearing all event flags
- usbd_hid_interface: rewrite USB HID interface code
- boards/xxx_WB55: enable USB HID now that it works on WB MCUs
- usbd_hid_interface: include extra header to build with threading
- lwip_inc: enable raw socket type
- mpconfigport.h: enable lwIP raw sockets
- sdcard: support configuring the SD/MMC bus width to 1 or 4 bits
- modpyb: support building with PY_PYB_LEGACY on and HW_USB_HID off
- usbd: introduce MICROPY_HW_USB_IS_MULTI_OTG to simplify USB config
- usbd: support USB device mode on STM32L432 MCUs
- boards/NUCLEO_L432KC: add config for USB VCP support
- usbd: make USB device FIFO sizes dynamically configurable
- i2c: fix generation of restart condition for hw I2C on F0/F7
- mphalport: put PYBD specific MAC code in board specific file
- mboot/Makefile: define "BUILDING_MBOOT" when building mboot
- boards/PYBD_SF2: exclude certain things when building mboot
- extint: fix EXTI mapping of PVD and RTC events for H7 MCUs
- stm32_it: include correct EXTI interrupt handlers for L0 MCUs
- dma: fix DMA config for L0 MCUs
- powerctrl: fix machine.bootloader() for L0 MCUs
- machine_adc: add machine.ADC class
- machine_adc: improve operation of ADC for H7, L4 and WB MCUs
- boards/stm32wb55_af.csv: fix ADC pin-channel function mapping
- mboot: support boards with only two LEDs
- boards/NUCLEO_L073RZ: fix typo in MCU name
- boards/MIKROE_CLICKER2_STM32: add MikroElektronika Clicker2 board
- boards/STM32F769DISC: fix number of SDRAM row bits
- board/NUCLEO_F746ZG: enable Ethernet periph, lwip and ussl
- usb: add support for VCP+MSC+HID mode, incl 2xVCP and 3xVCP
- usb: verify number of used endpoints doesn't exceed maximum
- lwip_inc: allocate additional MEMP_SYS_TIMEOUT when mDNS enabled
- lwip_inc: enable LWIP_NETIF_EXT_STATUS_CALLBACK for mDNS
- machine_adc: fix build for F4 and L4 MCUs that only have ADC1
- modusocket: fix NULL deref when accept() an unbound socket
- machine_i2c: add ability to specify I2C(4) by name
- can: factor CAN driver into low-level and Python bindings
- add support for FDCAN peripheral, exposed as pyb.CAN
- boards/NUCLEO_H743ZI: enable FDCAN on this board
- use mp_printf with MICROPY_ERROR_PRINTER for uncaught exceptions
- can: guard header file by MICROPY_HW_ENABLE_CAN
- usbd_cdc_interface: add CTS flow control option for USB VCP
- support disabling the compiler
- powerctrlboot: fix clock and PLL selection for HSI48 on F0 MCUs
- powerctrlboot: add support for HSI at 8MHz on F0 MCUs
- uart: add RTS/CTS pin configuration support to UART4
- provide port-specific implementation for Nimble on STM32
- mpconfigport.h: add modbluetooth module to stm32
- boards/PYBD: enable BLE for Pyboard D
- system_stm32: support selection of HSE and LSI on L4 MCUs
- boards: enable MICROPY_HW_RTC_USE_LSE on L4 boards
- {adc,machine_adc}: change ADC clock and sampling time for F0 MCUs
- usbdev: fix compile error if MICROPY_HW_USB_CDC_NUM is set to 2
- boards/PYBD_SF2: put nimble library in external QSPI XIP flash
- extract port-specific Nimble implementation
- mboot: add option to automatically reset when USB is disconnected
- sdcard: support boards with no SD card detect pin
- use hardware double sqrt on F7/H7 MCUs
- boards: add new board ADAFRUIT_F405_EXPRESS
- convert to use FROZEN_MANIFEST to specify frozen code
- adc: update ADC driver to work with the new H7 HAL
- adc: remove unused macro and channel check, and fix spacing
- adc: use IS_CHANNEL_INTERNAL macro to check for internal channels
- adc: fix sampling for internal channels on H7 MCUs
- mpu: save and restore the IRQ state when configuring MPU
- accel: rename MMA I2C macro constants to make it generic
- accel: add support for KXTJ3
- boards: add NADHAT_PYB405 board
- accel: fix Accel.read() method so it does read a byte
- powerctrlboot: fix config of systick IRQ priority on F0/L0/WB MCU
- sdram: fix to use new mpu_config_start/mpu_config_end signature
- Makefile: only enable hardware sqrt on parts that support it
- timer: fix Timer.freq() calc so mult doesn't overflow uint32_t
- add soft timer implementation, using SysTick at 1ms resolution
- add machine.Timer with soft timer implementation
- add support for RF coprocessor on WB55 MCUs
- boards: enable support for bluetooth on WB55 boards
- mpthreadport: include runtime.h to get defn of mp_raise_msg
- boards/stm32f405_af.csv: fix typo in ETH_RMII_REF_CLK on PA1
- nimble_hci_uart.c: prevent scheduler running during CYW-BT wakeup
- generalise flash mounting code so it supports arbitrary FS
- storage: make pyb.Flash configurable, and support ext block proto
- main: auto detect block device used for main filesystem
- moduos: add VfsLfs1 and VfsLfs2 to uos module, if enabled
- boards: enable LFS2 on PYBv1.x and PYBD boards
- storage: change storage_read/write_blocks to return int type
- storage: make start/len args of pyb.Flash keyword only
- qstrdefsport.h: remove unused qstrs and make USB ones conditional
- boards/NUCLEO_L073RZ: skip board-pin names for CPU only pins
- main: fix auto creation of pyb.Flash on boot with kw-only args
- mpconfigport.h: use IRQ_PRI_PENDSV to protect bluetooth ringbuf
- uart: add support for UART4/5 on L0 MCUs
- boards/xxx_WB55: enable littlefs2 on WB55 boards
- main: fix SKIPSD file detection so SD card is mounted by default
- Makefile: enable max buffer size on W5200 NIC when used with lwIP
- modusocket: handle case of NULL NIC in socket ioctl
- boards/PYBD_SF2: configure LEDs as inverted, for LED.intensity()
- boards/NUCLEO_F767ZI: add pins and config for using an SD card
- boards/NUCLEO_F767ZI: update pins, peripherals and total flash
- boards/NUCLEO_H743ZI: add extra pins and peripheral definitions
- timer: add missing TIM 1/15/16/17 IRQ handlers for H7 MCUs
- boards/PYBD: include webrepl helper scripts in frozen manifest

esp8266 port:
- uart: fix invalid ringbuf name when event driven REPL enabled
- provide custom machine_time_pulse_us that feeds soft WDT
- mpconfigport.h: enable lwIP raw sockets
- machine_uart: allow remapping UART TX/RX pins from 1/3 to 15/13
- put new profile code in iROM
- machine_adc: rename pyb_adc_* to machine_adc_*
- machine_adc: add read_u16 method and refactor
- add per-board configs, following other ports
- modules/ntptime.py: always close socket, and set day-of-week
- convert to use FROZEN_MANIFEST to specify frozen code
- allow building without a manifest
- boards: add manifest_release.py with files for a release
- modules/flashbdev.py: support extended block protocol
- moduos: add optional support for VfsLfs1 and VfsLfs2

esp32 port:
- machine_timer: reuse Timer handles, deallocate only on soft-reset
- add machine.SDCard class using built-in HW SD/MMC controller
- update to use ESP IDF v3.3-beta3
- modnetwork: still try to reconnect to WLAN even with AUTH_FAIL
- Makefile: include all driver/*.c source files in the build
- network_ppp: add ppp_set_usepeerdns(pcb, 1) when init'ing iface
- add support for hardware I2C
- Makefile: fix path expansion for ESPIDF_DRIVER_O
- Makefile: put OBJ and LIB rule additions in gen_espidf_lib_rule
- Makefile: simplify include of IDF source by using wildcards
- pin MicroPython tasks to a specific core
- Makefile: include CFLAGS_EXTRA in CFLAGS definition
- network_ppp: add authentication support to the PPP interface
- add support for mDNS queries and responder
- modules: on initial setup mount internal flash at root
- add per-board configs, following other ports
- add esp32.Partition class to expose partition and OTA funcs
- add 'config' function to network.LAN, reusing network.WLAN
- Makefile: fix subst->patsubst in ESPIDF_BOOTLOADER_SUPPORT_O
- machine_adc: add ADC.read_u16() method
- update to use ESP IDF v3.3
- boards/TINYPICO: switch to use QIO and 80MHz for SPI interface
- add VFS FAT partition to partitions.csv and mount it as the FS
- add support for ESP32-D2WD with 2MiB internal flash
- modules/inisetup.py: use bdev.ioctl instead of bdev.SEC_SIZE
- Makefile: add SDKCONFIG_H to QSTR_GLOBAL_REQUIREMENTS
- support building with ESP IDF 4.0-beta1
- add check to Makefile for pyparsing version
- add check to Makefile that the toolchain is in PATH
- main: use both 3.3 and 4.0 config vars to enable SPIRAM
- Makefile: fix printing of supported git hash
- enable native emitter
- implement BLE using Nimble from IDF 4.x
- boards: enable BLE by default when building with IDF 4.x
- add 4.x version of IDLE WDT config
- run NimBLE on the app core
- convert to use FROZEN_MANIFEST to specify frozen code
- machine_uart: add ability to invert UART pins
- boards: split out CPU frequency config, make 160MHz the default
- machine_hw_spi: fix exception msg when host is already in use
- Makefile: add correct arch to MPY_CROSS_FLAGS for native code
- remove unused "esponewire.c" in favour of extmod/modonewire
- esp32_partition: support extended block protocol
- moduos: enable uos.VfsLfs2 for littlefs filesystems
- boards/sdkconfig.base: resize SSL output buffer from 16 to 4kiB
- rtc: set system microseconds when setting time via RTC.datetime()
- machine_rtc: make RTC.memory size and availability configurable
- machine_rtc: reduce memory footprint of user mem functionality
- boards: enable ULP in base sdk configuration
- boards/TINYPICO: add tinypico.py, dotstar.py with custom manifest
- esp32_rmt: add initial support for RMT peripheral

javascript port:
- enable support for frozen bytecode via FROZEN_MPY_DIR

nrf port:
- led: adjust how board LEDs are defined
- clean up source by removing tabs, trailing spaces, non-ASCII chars
- machine/adc: add ADC.read_u16() method
- add ADC channel mapping to alt function table
- machine/adc: allow to pass a Pin object in to ADC constructor
- machine/adc: fix mapping of ADC channel to pin
- boards/make-pins.py: fix gen of board pins to use correct index
- Makefile: add support for flashing with a Black Magic Probe
- boards: add Particle Xenon board configuration (an nRF52840)
- boards: add board definition for uBlox Nina B1 series BLE modules
- i2c: add support for TWIM (EasyDMA)
- temp: move module configuration guard
- uart: add support for UARTE (EasyDMA)
- flash: update flash driver to use nrfx_nvmc driver
- led: expose public API for LED manipulation
- main: update the way the LED is used on startup
- add support to activate MICROPY_PY_SYS_STDFILES
- device: correct SPIM3 IRQ handler entry for nrf52840
- add tinyusb support for nrf52840
- boards: add support for pca10059
- add nrf9160 base support
- boards: add nrf9160 pca10090 board
- main: execute boot.py/main.py frozen modules without a file system
- boards/particle_xenon: enable USB CDC on Particle Xenon board

powerpc port:
- add initial port to bare metal PowerPC arch

samd port:
- add new port to Microchip SAMDxx microcontrollers
- make common linker scripts, rename board.mk to mpconfigboard.mk
- boards: add Adafruit Feather M0 Express board configuration
- boards: add Mini SAM M4 board configuration
- add minimum config for Atmel SAMD21-XPLAINED-PRO board

zephyr port:
- main: use mp_stack API instead of local pointer for stack top

docs:
- machine: add initial docs for new machine.SDCard class
- library/framebuf: add missing module reference in example code
- library/sys: add documentation for sys.atexit function
- pyboard: update name of mounted volume to match code
- pyboard: clarify initial files on pyboard and fix up formatting
- library: document that sys.version_info returns a 3-tuple only
- pyboard: emphasize the instructions for making a USB mouse
- reference/speed_python: update that read-only buffers are accepted
- reference/speed_python: add missing self to var caching example
- library/pyb.DAC.rst: correct frequency for triangle mode output
- rename machine.ADC docs to machine.ADCWiPy
- library: specify new machine.ADC class
- library/pyb.rst: update docs for pyb.usb_mode() function
- library/pyb.rst: update pyb.usb_mode() to mention VCP+MSC+HID
- library/pyb.USB_VCP.rst: add info about id and flow params
- develop/qstr.rst: add documentation for string interning
- library/bluetooth: add initial BLE documentation
- reference/glossary.rst: add new terms and reduce complexity of old
- library/bluetooth.rst: clarify gap_advertise adv_data behavior
- library/bluetooth.rst: explain how to increase char buffer size
- library/bluetooth.rst: fix typo in HR/UART services example
- esp8266/tutorial: make http_get sample function self contained
- library: clarify relation between machine and port-specific mods
- esp8266: add ntptime usage to esp8266 quickref
- fix spelling in various parts of the docs
- wipy/tutorial: link Blynk examples to the official library
- library: rename "array" module to "uarray"
- library/bluetooth: rename to "ubluetooth"
- move ubluetooth under "MicroPython-specific libraries"
- library: add documentation for extended block device protocol
- library/ubluetooth: add docs for gatts_set_buffer
- conf.py: fix path to favicon.ico
- templates/topindex.html: replace usage of deprecated defindex.html
- library/machine.SDCard.rst: fix various typos
- library/ubluetooth: fix name and link to FLAG_xxx constants
- reference: add docs describing use of pyboard.py
- library: add docs for pyb.Flash class
- add littlefs docs and a filesystem tutorial
- reference/filesystem: fix typo in block device code example
- reference/filesystem: add note and example about using filesystem
- library/ubluetooth: add note about API being under development
- library/uos: add notes and links about littlefs failures
- library/uos.rst: clarify why the extended interface exists
- esp8266/quickref: add note that machine.RTC is not fully supported
- reference: add documentation describing use of .mpy files
- develop: add documentation on how to build native .mpy modules
- esp32: add quickref and full docs for esp32.RMT class

travis:
- build PYBD_SF2 board as part of the stm32 job
- selectively fetch git submodules only when needed
- build esp8266 firmware as part of Travis CI
- build esp32 firmware as part of Travis CI
- enable performance benchmark tests on standard unix build
- add samd port to Travis build
- build stm32 mboot for PYBD_SF6 as part of CI
- switch unix stackless build to use clang
- build an stm32 board with threading enabled to test it with CI
- add new job to test unix port with sys.settrace enabled
- add ESP32 build with IDF v4
- build more stm32 boards to cover all supported MCUs
- build unix nanbox with PYTHON=python2
- add BLE submodules to ESP32 IDF4 build
- add esp8266 GENERIC_512K build to CI
- use "make submodules" to init required modules for each port
- add job to build and test unix minimal port
- add tests for building and importing dynamic native modules
- build urandom native module in coverage job

examples:
- bluetooth: add basic BLE peripheral examples
- bluetooth: use UUIDs directly to add services to adv payload
- bluetooth/ble_uart_peripheral.py: add usage demo
- embedding: replace symlink of mpconfigport.h with real file
- bluetooth/ble_uart_peripheral: use append mode for RX char
- embedding: remove obsolete fatfs files from build
- bluetooth: add helpers for decoding advertising payloads
- bluetooth: add example for reading temperature sensor
- natmod: add btree example
- natmod: add uheapq example
- natmod: add uzlib example
- natmod: add framebuf example
- natmod: add ure example
- natmod: add features1 and features2 examples
- natmod: add urandom native module example
- network: add testing key/cert to SSL HTTP server example
- natmod: add very simple features0 example to compute factorial

miscellaneous:
- top: add CODEOFCONDUCT.md document based on the PSF code of conduct
- gitignore: put build-*/ pattern in top-level gitignore file
- gitattributes: mark *.a files as binary

Improved mpy format with support for native code, and new JavaScript port

In this release the mpy file format has been moved to version 4 and has
some significant improvements: mpy file size is reduced on average by about
35%, loading time of mpy files is reduced by about 40%, and they now have
support to save native, viper and inline assembler code (or machine code
generated from any other source).  Size reduction of mpy files was achieved
by adding a qstr window to reuse past qstrs when encoding them, by packing
qstrs directly in the bytecode, and by defining a static qstr set.

Some VM opcodes were also changed to fix a bug when doing a break/continue
out of a finally block, and to make some simplifications.  In particular
POP_BLOCK and POP_EXCEPT opcodes were replaced with POP_EXCEPT_JUMP.

Most uppercase macros have been converted to lowercase to make a more
consistent C API, including all MP_OBJ_IS_xxx and MP_xxx_SLOT_IS_FILLED
macros.

The default PYTHON makefile variable is now changed from "python" to
"python3", but Python 2 is still supported via "make PYTHON=python2".

The mpy-cross compiler supports the new mpy version 4 and has new command
line options: "-march=<arch>" to select the native emitter, and "--version"
to print the MicroPython version and the mpy version.  Also mpy-tool.py has
support for freezing native code.

A module system for external, user C modules has been implemented and
documentation for this is available in the new "docs/develop" section.

A new "javascript" port has been added which targets JavaScript as the
machine via Emscripten.  This allows to run MicroPython as an application
within node.js, and to run it within a browser (among other things).

All bare-metal ports have the following improvements: machine.sleep() is
now machine.lightsleep(), and both lightsleep() and deepsleep() now take an
optional argument which is the maximum time to sleep in milliseconds.
These ports also now allow freezing of boot.py and main.py using the usual
methods.  And a new I2C method i2c.writevto(addr, vect) is added which can
be used to write a tuple/list of buffers all at once to an I2C device.

The stm32 port now has a fully integrated Ethernet MAC driver (see the
network.LAN class) using lwIP for the TCP/IP stack, and sockets were made
significantly more robust.  Support for F413 MCUs was added.  There are
also some minor user-facing changes to this port:
- machine.UART (and pyb.UART) now defaults to timeout=0 (was 1000ms) which
  gives UARTs a non-blocking behaviour.
- The USB REPL is now configurable using uos.dupterm, and by default
  pyb.USB_VCP(0) is put on dupterm slot 1 before boot.py is executed.  To
  disable the default REPL use: uos.dupterm(None, 1).
- pyb.DAC(id) will now only reset the DAC the first time it is called; to
  get the old behaviour pass the bits parameter like: pyb.DAC(id, bits).
- pyb.DAC.noise() and pyb.DAC.triangle() now output at full scale.
- The system will not recreate boot.py if it's missing (it will only create
  it if the filesystem is corrupt, or when doing a factory reset).

For the esp32 port, the build process has been updated to align better with
the ESP IDF and now uses sdkconfig to configure features.  Dual core mode
is now enabled by default, SPIRAM is in memory-mapped mode so all of it can
be used for the MicroPython heap, there is support to change the CPU
frequency, and the WDT now panics and resets the device if it times out.

A detailed list of changes follows.

py core:
- remove calls to file reader functions when these are disabled
- add optional support for 2-argument version of built-in next()
- compile: swap order of pop_block/pop_except in "except as" handler
- warning: support categories for warnings
- builtinhelp: only print help re FS modules if external import enabled
- downcase all MP_OBJ_IS_xxx macros to make a more consistent C API
- downcase MP_xxx_SLOT_IS_FILLED inline functions
- mkenv.mk: change default PYTHON variable from "python" to "python3"
- qstr: evaluate find_qstr only once then pass to Q_GET_HASH macro
- obj.h: remove obsolete mp_obj_new_fun_viper() declaration
- objfun: make fun_data arg of mp_obj_new_fun_asm() a const pointer
- eliminate warnings about unused arguments when debugging disabled
- compile: fix handling of unwinding BaseException in async with
- compile: add optimisation to compile OrderedDict inplace
- objexcept: fix hash of exc str created in mp_obj_new_exception_msg
- py.mk: update lwip build config to work with latest lwip version
- fix VM crash with unwinding jump out of a finally block
- vm: remove currently_in_except_block variable
- replace POP_BLOCK and POP_EXCEPT opcodes with POP_EXCEPT_JUMP
- persistentcode: add a qstr window to save mpy files more efficiently
- persistentcode: pack qstrs directly in bytecode to reduce mpy size
- persistentcode: define static qstr set to reduce size of mpy files
- add independent config for debugging sentinel object values
- emitnative: consolidate where HASCONSTS is set to load-const-obj fun
- emitnative: provide concentrated points of qstr emit
- emitnative: adjust accounting of size of const_table
- emitglue: remove union in mp_raw_code_t to combine bytecode & native
- add support to save native, viper and asm code to .mpy files
- persistentcode: bump .mpy version to 4
- allow registration of modules at their definition
- implement a module system for external, user C modules
- update and rework build system for including external C modules
- move mp_native_type_from_qstr() from emitnative.c to nativeglue.c
- nativeglue: rename native convert funs to match other native helpers
- compile: add support to select the native emitter at runtime
- compile: support multiple inline asm emitters
- compile: check that arch is set when compiling native, viper or asm
- runtime: remove long-obsolete MICROPY_FSUSERMOUNT init code
- scheduler: convert micropythyon.schedule() to a circular buffer
- nlrthumb: add support for iOS where the C func is _nlr_push_tail
- makedefs: use io.open with utf-8 encoding when processing source
- runtime: optimise to not create temp float for int to power negative
- runtime: fix mp_unpack_ex so seq can't be reclaimed by GC during use
- mpprint: support printing %ld and %lu formats on 64-bit archs
- asmthumb: support asm_thumb code running on normal ARM processors
- native: improve support for bool type in viper functions
- remove "if (0)" and "if (false)" branches
- objgenerator: fix handling of None passed as 2nd arg to throw()
- objgenerator: remove unneeded forward decl and clean up white space
- misc.h: rename _MP_STRINGIFY to not use leading underscore in ident
- persistentcode: change "len" type to size_t for mp_obj_str_get_data
- objarray: add support for memoryview.itemsize attribute
- objarray: add decode method to bytearray
- update makefiles to use $(CAT) variable instead of hard coded "cat"
- update makefiles to use $(TOUCH) instead of hard coded "touch"

extmod:
- moduzlib: update to uzlib 2.9.2
- modlwip: add support for polling UDP sockets for writability
- moduhashlib: include implementation of sha256 only when required
- convert legacy uppercase macro names to lowercase
- moduwebsocket: refactor `websocket` to `uwebsocket`
- modlwip: change #ifdef to #if for check of MICROPY_PY_LWIP
- modlwip: fix bug when polling listening socket with backlog=1
- modlwip: add concurrency protection macros
- modwebrepl: fix logic to handle a put of file of size 0
- vfs_fat: update for new oofatfs version
- modlwip: fix case where concurrency lock isn't released on error
- moduselect: adjust select_select and poll_register to use size_t
- vfs_fat: fallback to FAT32 if standard FAT16/SFD format fails
- modlwip: handle case of connection closing while on accept queue
- modlwip: handle case of accept callback called with null PCB
- modlwip: protect socket.accept with lwIP concurrency lock
- modlwip: free any stored incoming bufs/connections on TCP error
- modlwip: use correct listening socket object in accept callback
- modlwip: abort TCP conns that didn't close cleanly in a while
- modurandom: add init method to seed the Yasmarang generator
- machine_signal: fix fault when no args are passed to Signal()
- modussl_mbedtls: support non-blocking handshake
- modussl_axtls: add non-blocking mode support
- moducryptolib: add optional AES-CTR support
- modujson: handle parsing of floats with + in the exponent
- machine_i2c: change C-level API to allow split I2C transactions
- machine_i2c: remove need for temporary memory in writemem() call
- machine_i2c: add i2c.writevto() that can write a vector of bufs
- modlwip: free any incoming bufs/connections before closing PCB
- modlwip: register TCP close-timeout callback before closing PCB

lib:
- utils/pyexec: implement paste mode with event driven REPL
- utils/printf: exclude __GI_vsnprintf alias for gcc 9 and above
- utils/gchelper_m3: add license header and clean up code
- utils/gchelper_m3: add gc_helper_get_sp() function
- utils/gchelper: add gchelper.h header file for assembler functions
- netutils: add function to print tracing info for Ethernet frames
- oofatfs: update oofatfs library to R0.13c working branch
- oofatfs: update ffconf.h config for new oofatfs version
- oofatfs: update oofatfs library to fix issue with logic not
- stm32lib: update library to fix F7 MMC capacity calculation
- utils/pyexec: add pyexec_file_if_exists() helper function
- utils: make pyexec_file_if_exists run frozen scripts if they exist
- utils/interrupt_char: invalidate interrupt char at start up
- stm32lib: update library to fix UART9/10 baudrate on F4 MCUs
- nrfx: upgrade nrfx to v1.7.1 plus a UART bug fix

drivers:
- memory/spiflash: rework wait_sr to fix uninit'd variable 'sr'
- display/ssd1306.py: change to use new i2c.writevto() method

tools:
- mpy-tool.py: add support for freezing native code
- upip.py: use "raise arg" instead of no-arg raise form, for native
- pyboard.py: add missing line from example usage comments
- mpy-tool.py: adjust use of super() to make it work with Python 2
- mpy-tool.py: fix init of QStrWindow, and remove unused variable
- pyboard.py: don't accumulate output data if data_consumer used
- upip.py: add support for multiple index URLs with custom default

tests:
- basics: add tests for try-except-else and try-except-else-finally
- run-tests: support running native tests via mpy
- import: add test for importing x64 native code
- extmod: add test for FAT filesystem on a very large block device
- run-tests: ignore exception in process kill when ending repl test
- micropython: add some tests for failed heap allocation
- skip tests needing machine module if (u)machine doesn't exist
- ussl_basic: disable setblocking() calls
- basics/sys1.py: add test for calling sys.exit() without any args
- pyb: update UART expected output now that default timeout is 0
- basics: add coverage tests for memoryview attributes

mpy-cross:
- enable building of x64 native .mpy files
- add "-march=<arch>" option to select native emitter
- support compiling with MICROPY_PY___FILE__ enabled
- automatically select ARMV6 arch when running on such a host
- add --version command line option to print version info

all ports:
- change PYB message prefix to MPY
- convert legacy uppercase macro names to lowercase
- update to work with new oofatfs version
- {stm32,esp8266}: set mpy-cross native arch for frozen native code
- convert to use pyexec_file_if_exists() to execute boot/main.py

unix port:
- mpthreadport: add thread deinit code to stop threads on exit
- mpthreadport: cleanup used memory on thread exit
- mpthreadport: remove busy wait loop in thread garbage collection
- modmachine: handle repeated /dev/mem open errors
- modffi: eliminate unused-argument warning when debugging disabled
- Makefile: update coverage tests to match those in Travis
- mpthreadport: use named semaphores on Mac OS X
- gcollect: make sure stack/regs get captured properly for GC
- coverage: add test for printing literal % character
- modusocket: fix use of setsockopt in usocket.settimeout impl
- modusocket: raise ETIMEDOUT when connect or accept has timeout

windows port:
- fix line wrapping behaviour on the REPL

qemu-arm port:
- rework to run bare-metal on boards with Cortex-M CPUs
- use gchelper code to get registers for GC scanning

stm32 port:
- implement machine.lightsleep()
- rtc: check RTCEN=1 when testing if RTC is already running on boot
- usbdev: add USB config option for board being self powered
- usbdev: add USB config option for max power drawn by the board
- main: make board-defined UART REPL use a static object and buffer
- boards/stm32f429_af.csv: fix typos in UART defs Tx->TX and Rx->RX
- mboot: add option to autodetect the USB port that DFU uses
- sdcard: don't use SD clock bypass on F7 MCUs
- usb: add flow control option for USB VCP data received from host
- boards/make-pins.py: add basic support for STM32H7 ADC periphs
- boards/stm32h743_af.csv: add ADC entries to pin capability table
- adc: add basic support for ADC on a pin on STM32H7 MCUs
- mboot: use USB HS as main USB device regardless of USB_HS_IN_FS
- mboot: add support for STM32F769 MCUs
- mboot: add support for GPIO ports G, H, I and J
- mboot: allow deploying via deploy-stlink
- usb: use USB HS as main USB device regardless of USB_HS_IN_FS
- usbd_conf: fully support USB HS with external PHY
- modmachine: make bootloader() enter custom loader if it's enabled
- boards/STM32F769DISC: support the use of USB HS with external PHY
- boards/STM32F769DISC: configure for use with mboot by default
- systick: rename sys_tick_XXX functions to systick_XXX
- systick: make periodic systick callbacks use a cyclic func table
- pendsv: clean up pendsv IRQ handler and eliminate duplicate code
- pendsv: add ability to schedule callbacks at pendsv IRQ level
- systick: provide better compile-time configurability of slots
- modnetwork: change lwIP polling to be based on background systick
- move gchelper assembler code to lib/utils for use by other ports
- gccollect: use gchelper.h header instead of explicit declaration
- pendsv: fix inline asm constant and prefix with # character
- mboot/Makefile: support specifying BOARD_DIR for custom board
- boards/NUCLEO_L476RG: add support for RNG, DAC and CAN1
- boards/make-pins.py: add cmdline options to support use by mboot
- mboot/Makefile: generate all pin header files from board pins.csv
- mboot/mphalport.h: include genhdr/pins.h for access to pin names
- qspi: use static af functions for pin configuration
- mboot: add support for loading gzip'd firmware from a filesystem
- mboot: move some BSS vars to new section that isn't zeroed out
- mboot: add support script which can program mboot and application
- modmachine: add ability to pass through user data to mboot
- mboot: add hook to run board-specific code early on startup
- boards/stm32f429.ld: increase uPy heap size by 64k for F429 MCU
- extint: fix ExtInt to work with non-GPIO pins
- extint: fix RTC Alarm/FS USB EXTI constants for L4
- make-stmconst.py: improve regex to parse more constants
- extint: add non-GPIO EXTI IRQ sources for F0
- extint: remove unused (and incorrect) EXTI defines
- stm32_it: fix RTC IRQ handler to handle all EXTI IRQs on F0 MCUs
- sdram: increase GPIO speed for SDRAM interface to "very high"
- boards/NUCLEO_F767ZI: fix up comments about HCLK computation
- mphalport: add mp_hal_get_mac() helper function
- eth: add low-level Ethernet MAC driver
- network_lan: add high-level network.LAN interface to ETH driver
- mpconfigport.h: enable lwIP concurrency protection mechanism
- modnetwork: don't call NIC callback if it's NULL
- boards/NUCLEO_F767ZI: enable lwIP and Ethernet peripheral
- boards/STM32F7DISC: enable lwIP and Ethernet peripheral
- boards/STM32F769DISC: enable lwIP and Ethernet peripheral
- boards/NUCLEO_F429ZI: enable lwIP and Ethernet peripheral
- qspi: enable sample shift and disable timeout counter
- Makefile: allow a board to specify its linker sections for FW
- boards/STM32F769DISC: use external QSPI flash to store some code
- use global lwip build config and support building without lwip
- boards: update to use new build config for lwip component
- add compile-time option to use HSI as clock source
- mboot: update to match latest oofatfs version
- allow to build with threading with the GIL disabled
- qspi: set pin speed to very-high and allow to config some options
- usb: allow to override USB strings & VID/PID in app and mboot
- stm32_it: guard UART7_IRQHandler with check for UART7 define
- mboot: set USE_MBOOT=1 by default in the Makefile
- system_stm32: provide default value for HSI calibration
- mpconfigport.h: remove malloc/free/realloc helper macros
- boards/STM32L476DISC: enable servo support on STM32L476DISC board
- Makefile: allow to override CROSS_COMPILE with included Makefile
- make default USB_VCP stream go through uos.dupterm for main REPL
- timer: expose the PWM BRK capability of Timer 1 and 8
- uart: handle correctly the char overrun case of RXNE=0 and ORE=1
- rename MICROPY_HW_HAS_SDCARD to MICROPY_HW_ENABLE_SDCARD
- add support for MMC driver, exposed via pyb.MMCard class
- moduos: allow to compile again without USB enabled
- network_wiznet5k: add ability to trace Ethernet TX and RX frames
- network_wiznet5k: add ability to set the MAC address
- network_wiznet5k: automatically set MAC if device doesn't have one
- i2cslave: add support for H7 MCUs
- usbd_conf: add support for USB HS peripheral on H7 MCUs
- mboot: add support for H7 MCUs, with H743 flash layout
- boards/NUCLEO_H743ZI: add config options to support mboot
- boards/NUCLEO_L432KC: disable complex nos and default frozen mods
- rtc: add auto-LSE-bypass detection with fallback to LSE then LSI
- rtc: remove unused LSE detection code
- rtc: remove non-ASCII mu-character from source code comment
- timer: correctly initialise extended break settings on F7/H7/L4
- system_stm32f0: enable PWR clock on startup
- system_stm32f0: add support for using HSE and PLL as SYSCLK
- powerctrl: enable EIWUP to ensure RTC wakes device from standby
- dac: rework DAC driver to use direct register access
- usbdev: make USB device descriptors at runtime rather than static
- usb: add USB device mode for VCP+VCP without MSC
- powerctrl: deselect PLLSAI as 48MHz src before turning off PLLSAI
- usb: remove mp_hal_set_interrupt_char now that it's reset at boot
- main: increase default UART REPL rx buffer from 64 to 260 bytes
- powerctrl: support changing frequency when HSI is clock source
- flash: fix bug computing page number for L432 page erase
- add support for F413 MCUs
- boards: add NUCLEO_F413ZH board configuration
- machine_uart: change default UART timeout to 0, for non blocking
- move factory reset files and code to separate source file
- usbd_cdc_interface: don't retransmit chars if USB is reconnected
- rtc: allow overriding startup timeouts from mpconfigboard
- dma: initialise all members of DMA structs for H7 MCUs
- dma: always reset and configure the H7 DMA peripheral
- spi: enable SPI IRQs and add IRQHandlers for H7 MCUs
- irq: fix IRQ_ENABLE_STATS stats config to work on all MCUs
- boards/NUCLEO_H743ZI: enable SPI3 on this board
- modmachine: create dedicated asm function to branch to bootloader
- adc: fix VBAT_DIV to be 4 for STM32F411
- machine_i2c: update to support new C-level I2C API
- i2c: make timeout for hardware I2C configurable
- machine_i2c: simplify ROM initialisation of static HW I2C objects
- i2c: support setting the I2C TIMINGR value via keyword arg
- sdcard: add switch break to ensure only correct SD/MMC IRQ is run
- sdram: update MPU settings to block invalid region, change attrs
- mboot/README: fix some typos, describe bootloader and fwupdate.py
- modmachine: in bootloader() disable caches before reset of periphs

cc3200 port:
- mods/modussl: fix ca_certs arg validation in mod_ssl_wrap_socket
- modmachine: rename machine.sleep to machine.lightsleep
- use common gchelper_m3.s code from lib/utils
- mpconfigport.h: disable compiler optimisation of OrderedDict

esp8266 port:
- modmachine: implement optional time_ms arg to machine.deepsleep
- modmachine: rename machine.sleep to machine.lightsleep
- modmachine: implement simple machine.lightsleep function
- modmachine: in lightsleep, only waiti if wifi is turned off
- modmachine: call ets_event_poll after waiti in machine.idle
- modmachine: handle overflow of timer to get longer periods
- fix ticks_ms to correctly handle wraparound of system counter

esp32 port:
- don't put py/scheduler.o in iRAM, it's no longer needed
- Makefile: put all IDF compenents in .a libs to use IDF ld script
- update to latest ESP IDF using sdkconfig and new ldgen procedure
- machine_timer: deinit all active timers on soft reset
- Makefile: make sure that directory exists for sdkconfig.h
- boards: use auto xtal freq config instead of default 40MHz
- modsocket: fix crashes when connect/bind can't resolve given addr
- modmachine: rename machine.sleep to machine.lightsleep
- use SPIRAM in mem-map mode so all of it can be used for uPy heap
- modmachine: add support for changing the CPU frequency
- modsocket: fix usocket.send to accept anything with buffer proto
- modsocket: change socket.socket to be socket type rather than fun
- network_lan: add arg to constructor to set clock mode for ETH PHY
- modnetwork: catch and report Ethernet events
- network_lan: make power arg to constructor optional
- modnetwork: fix wifi.isconnected to return False after disconnect
- modnetwork: implement RSSI for WiFi STA via WLAN.status('rssi')
- modnetwork: remove redundant esp_log include
- Makefile: add some missing IDF source files to bootloader and app
- mphalport: use ets_delay_us for mp_hal_delay_us_fast
- machine_pin: make it so None as pull value disables pull up/down
- machine_pin: add new PULL_HOLD pin pull mode
- machine_pin: rework pull mode config to fix GPIO hold feature
- mpthreadport: exit vPortCleanUpTCB early if threading not init'd
- boards: enable dual core support by default
- boards/sdkconfig: disable WDT check of idle task on CPU1
- README: add info about pyparsing and the correct Python version
- machine_wdt: add timeout arg to select interval, make WDT panic
- modnetwork: change type to size_t for uses of mp_obj_str_get_data
- machine_uart: implement UART.deinit() method
- network_ppp: add a timeout for closing PPP connection
- machine_touchpad: use HW timer for FSM to enable wake-on-touch
- modsocket: raise EAGAIN when accept fails in non-blocking mode

javascript port:
- add new port targeting JavaScript via Emscripten
- fix Emscripten async load, and to compile with modern clang
- library: use Buffer.alloc() since new Buffer() is deprecated
- pass (error) exit value out from script to process caller
- Makefile: fix unrepresentable float error by using clamp
- library: print data as raw bytes to stdout so unicode works

nrf port:
- modmachine: rename machine.sleep to machine.lightsleep
- uart: use formula instead of switch for baudrate calculation
- uart: remove unused machine.UART() parameters
- shrink "<peripheral> does not exist" error messages
- pin: cleanup Pin.__str__ to print relevant information
- pin: print pull information in Pin.__str__
- ticker: remove duplicate NRFX_IRQ_PRIORITY_SET
- timer: fix disabling Timer 1 when using soft PWM
- readme: update link to nrfjprog download
- bluetooth: improve advertisment behavior for nrf52 targets
- bluetooth: resolve compilation warning in ble_drv.c
- readme: update make flash command when defining board
- pwm: remove superfluous NULL in machine_hard_pwm_instances
- bluetooth: add support for SoftDevice s132 version 6.1.1
- board: migrate all nrf52832 targets to new BLE stack
- bluetooth: deprecate use of SoftDevice s132 v6.0.0
- bluetooth: add support for SoftDevice s140 version 6.1.1
- board: migrate nrf52840 target to new BLE stack
- bluetooth: deprecate use of SoftDevice s140 v6.0.0
- readme: add section about LTO
- Makefile: update to match latest oofatfs version
- boards: add support for BLYST Nano module based boards
- change types to size_t for all uses of mp_obj_str_get_data
- machine/i2c: update to support new C-level I2C API
- nrfx_glue: adapt to nrfx v.1.7.1
- uart: change UART driver to be non-blocking and use IRQs
- mpconfigport.h: enable MICROPY_KBD_EXCEPTION by default
- uart: make UART print output something, and add write method
- mphalport: use wfi to save power while waiting at the UART REPL

zephyr port:
- modzephyr: revamp stacks_analyze() call
- modzsensor: rename "TEMP" sensor channel to "DIE_TEMP"
- prj_minimal.conf: switch to CONFIG_STDOUT_CONSOLE
- Makefile: proxy ram_report, rom_report targets from Zephyr
- prj_frdm_k64f.conf: add fxos8700 sensor
- prj_frdm_kw41z.conf: add new board configuration
- i2c: add support for hardware i2c
- CMakeLists.txt: set AR to point to the Zephyr toolchain exe
- machine_i2c: update to support new C-level I2C API
- switch back to enabling I2C in board-specific configs

docs:
- machine: change sleep to lightsleep and add timeout arguments
- convert all cases of machine.sleep to machine.lightsleep
- ure: fix match.group signature to indicate index param is required
- uos: document extra requirements on stream objs passed to dupterm
- pyboard: add link to pyboard v1.1 schematic and layout PDF
- pyboard: make pyboard v1.1 pinout the default shown in quickref
- develop: fix typos in C-module example for example_add_ints
- library/machine.Pin: add PULL_HOLD constant to possible pin pulls
- esp32: add a note to quickref about use of Pin.PULL_HOLD
- esp32: add example for pin isolation in combination with deepsleep
- develop: remove paragraph that was copied in error from other doc
- cmodules: fix example to globally define MODULE_EXAMPLE_ENABLED
- cmodules: note the various ways MODULE_EXAMPLE_ENABLED can be set
- esp8266: add tutorial for APA102 LEDs
- esp32: correct quickref for ESP32 hardware SPI with non-default IO
- machine.I2C: add writevto method to write a vector of byte bufs
- pyboard/quickref: refer to new machine.I2C instead of old pyb.I2C

travis:
- update to use Ubuntu 16.04 Xenial for CI builds
- enable test for running native code via mpy

Vast improvements to native emitter, new nrf port, unified documentation

In this release there are a wide range of improvements and additions to
both the core and the ports.  In the core the main improvement was to the
native emitter to have much more comprehensive support for general Python
features, such as generators and complex exception handling, and the
generated machine code is smaller and retains its efficiency.  Elsewhere,
fuzzy testing was used to find and eliminate some corner-case bugs, user
classes were optimised when they don't use special accessors, underscores
in numeric literals are now supported (PEP515), and the uio.IOBase class
was added to allow user defined streams.

For the extended modules there is now a VfsPosix filesystem component,
a new ucryptolib module with AES support, addition of ure.sub() and of
uhashlib.md5, and the lwIP socket implementation now has working TCP
listen/accept backlog.

Compared to the last release the minimal baseline core code size is reduced
by about 2.2%, down by roughly 1500 bytes for bare-arm port and 3500 bytes
for minimal x86 port.  Most other ports have increased in size due to the
addition of new features (eg ucryptolib, ure.sub).

The stm32 port sees the introduction of a new bootloader -- mboot -- which
supports DFU upload via USB FS, USB HS, as well as a custom I2C protocol,
and also support to program external SPI flash.  There is significant
refactoring of the USB device driver, improved VCP throughput, and support
for 2x VCP interfaces on the one USB device.  lwIP has been integrated, and
support added for SDRAM.  Cortex-M0 CPUs are now supported along with
STM32F0 MCUs.

For the esp8266 port the heap is increased by 2kbytes, the radio is
automatically put to sleep if no WLAN interfaces are active, and the UART
can now be disconnected from the REPL and its RX buffer length configured.
Upon soft-reset sockets are now cleaned up.

The esp32 port has added support for external SPI RAM, PPPoS functionality,
improved performance and stability when using threads, and other general
bug fixes.

There is a new nrf port for Nordic MCUs, currently supporting nRF51x and
nRF52x chips.

The docs have now been unified so there is just one set of documentation
covering all ports.  And initial documentation for the esp32 port is added.

There are two changes at the Python API level that are not backwards with
previous versions:
- uos.dupterm now requires that a stream passed to it is derived from
  uio.IOBase (or is a native stream object).
- The esp32 neopixel driver has had its default timing changed from 400kHz
  to 800kHz; existing code that didn't explicitly specify the "timing"
  parameter in the NeoPixel constructor may need to be updated to specify
  this as "timing=0" to get 400kHz timing.

A detailed list of changes follows.

py core:
- mpconfig.h: be stricter when autodetecting machine endianness
- mpstate.h: adjust start of root pointer section to exclude non-ptrs
- nlrx86: use naked attribute on nlr_push for gcc 8.0 and higher
- vm: adjust #if logic for gil_divisor so braces are balanced
- objfun: fix variable name in DECODE_CODESTATE_SIZE() macro
- vm: use enum names instead of magic numbers in multi-opcode dispatch
- vm: improve performance of opcode dispatch when using switch stmt
- repl: fix handling of unmatched brackets and unfinished quotes
- misc.h: add MP_STATIC_ASSERT macro to do static assertions
- compile: change comment about ITER_BUF_NSLOTS to a static assertion
- emitbc: avoid undefined behavior calling memset() with NULL 1st arg
- parsenum: use int instead of mp_int_t for parsing float exponent
- parsenum: avoid undefined behavior parsing floats with large exponents
- objfloat: fix undefined shifting behavior in high-quality float hash
- mpz: avoid undefined behavior at integer overflow in mpz_hash
- objfloat: fix undefined integer behavior hashing negative zero
- gc: when GC threshold is hit don't unnecessarily collect twice
- parsenum: adjust braces so they are balanced
- modbuiltins: add support for rounding integers
- objgenerator: save state in old_globals instead of local variable
- objgenerator: protect against reentering a generator
- emit: combine fast and deref into one function for load/store/delete
- emit: combine yield value and yield-from emit funcs into one
- emit: combine build tuple/list/map emit funcs into one
- emit: combine name and global into one func for load/store/delete
- emit: combine load/store/delete subscr into one emit function
- emit: combine load/store/delete attr into one emit function
- emit: combine break_loop and continue_loop into one emit function
- emit: combine import from/name/star into one emit function
- emit: merge build set/slice into existing build emit function
- emit: combine setup with/except/finally into one emit function
- objtype: fix assertion failures in mp_obj_new_type by checking types
- objtype: fix assertion failures in super_attr by checking type
- stream: move definition of mp_stream_p_t from obj.h to stream.h
- reader: allow MICROPY_VFS_POSIX to work with MICROPY_READER_POSIX
- mpconfig.h: add default MICROPY_VFS_FAT config value
- obj.h: introduce a "flags" entry in mp_obj_type_t
- objtype: don't expose mp_obj_instance_attr()
- objtype: optimise instance get/set/del by skipping special accessors
- gc: add gc_sweep_all() function to run all remaining finalisers
- lexer: add support for underscores in numeric literals
- modio: add uio.IOBase class to allow to define user streams
- mkrules.mk: regenerate all qstrs when config files change
- stream: introduce and use efficient mp_get_stream to access stream_p
- objarray: replace 0x80 with new MP_OBJ_ARRAY_TYPECODE_FLAG_RW macro
- add checks for stream objects in print() and sys.print_exception()
- compile: combine break and continue compile functions
- compile: combine subscript_2 and subscript_3 into one function
- compile: combine global and nonlocal statement compile functions
- compile: combine or_test and and_test compile functions
- compile: combine expr, xor_expr and and_expr into one function
- compile: handle return/break/continue correctly in async with
- objgenerator: eliminate need for mp_obj_gen_wrap wrapper instances
- obj.h: fix broken build for object repr C when float disabled
- simplify some cases of accessing the map of module and type dict
- objdict: make mp_obj_dict_get_map an inline function
- objmodule: make mp_obj_module_get_globals an inline function
- obj.h: give compile error if using obj repr D with single-prec float
- malloc: give a compile warning if using finaliser without GC
- objgenerator: implement __name__ with normal fun attr accessor code
- emitnative: optimise for iteration asm code for non-debug build
- runtime: use mp_obj_new_int_from_ll when return int is not small
- stream: introduce MP_STREAM_GET_FILENO ioctl request
- objstr: in format error message, use common string with %s for type
- asmthumb: optimise native code calling runtime glue functions
- mpconfig.h: introduce MICROPY_DEBUG_PRINTER for debugging output
- fix compiling with debug enabled and make more use of DEBUG_printf
- emitnative: factor common code for native jump helper
- emitnative: fix x86 native zero checks by comparing full word
- asmx86: use generic emit function to simplify cmp emit function
- emitnative: fix native locals stack to start at correct location
- emitnative: simplify handling of exception objects from nlr_buf_t
- emitnative: allocate space for local stack info as it's needed
- compile: for dynamic compiler, widen literal 1 to get correct shift
- py.mk: don't hardcode path to libaxtls.a
- gc: in gc_alloc, reset n_free var right before search for free mem
- objarray: allow to build again when bytearray is disabled
- stream: adjust mp_stream_posix_XXX to take void*, not mp_obj_t
- emitnative: use small tables to simplify handling of local regs
- asmxtensa: handle function entry/exit when stack use larger than 127
- asm*: support assembling code to jump to a register, and get PC+off
- emitnative: optimise and improve exception handling in native code
- asmxtensa: fix bug with order of regs in addi encoding
- asmxtensa: optimise loading local addr and support larger offsets
- emitnative: fix bug with store of 16 and 32 values in viper ARM mode
- asmxtensa: use narrow version of add instr to reduce native code size
- emitnx86: fix number of args passed to mp_setup_code_state, 4 not 5
- vm: fix handling of finally-return with complex nested finallys
- emitnative: cancel caught exception once handled to prevent reraise
- emitnative: add support for return/break/continue in try and with
- compile: factor code that compiles start/end of exception handler
- py.mk: build axtls library directly from its source files
- runtime: fix incorrect test for MICROPY_PORT_DEINIT_FUNC
- objarray: bytearray: allow 2nd/3rd arg to constructor
- emitnative: fix try-finally in outer scope, so finally is cancelled
- fix native functions so they run with their correct globals context
- optimise call to mp_arg_check_num by compressing fun signature
- asmx64: fix bug in assembler when creating disp with r13 and 0 offset
- {asmx86,asmx64}: extend test_r8_with_r8 to accept all 8 lower regs
- emit: move MP_EMIT_OPT_xxx enums from compile.h to emitglue.h
- emit: remove need to call set_native_type to set native/viper mode
- emit: remove need to call set_native_type to set viper return type
- emit: completely remove set_native_type, arg type is set in compiler
- compile: merge viper annotation and normal param compilation stages
- compile: factor code that compiles viper type annotations
- emitnative: reuse mp_native_type_from_qstr when searching for a cast
- make viper functions have the same entry signature as native
- emitnative: support arbitrary number of arguments to viper functions
- emitnative: use macros instead of raw offsetof for slot locations
- emitnative: make viper funcs run with their correct globals context
- asmxtensa: make indirect calls using func table, not raw pointers
- asmthumb: detect presence of I-cache using CMSIS macro
- objtype: clarify comment about configuring inplace op methods
- shorten error messages by using contractions and some rewording
- objstr: make % (__mod__) formatting operator configurable
- modbuiltins: make oct/hex work when !MICROPY_PY_BUILTINS_STR_OP_MODULO
- objgenerator: implement PEP479, StopIteration convs to RuntimeError
- parsenum: avoid rounding errors with negative powers-of-10
- modmath: add math.factorial, optimised and non-opt implementations
- objstr: format: return bytes result for bytes format string
- fix msvc C++ compiler warnings with MP_OBJ_FUN_MAKE_SIG macro
- vm: make small optimisation of BUILD_SLICE opcode
- objfloat: fix abs(-0.0) so it returns 0.0
- emitnative: place const objs for native code in separate const table
- asm*: remove ASM_MOV_REG_ALIGNED_IMM emit macro, it's no longer used
- emitnative: change type of const_table from uintptr_t to mp_uint_t
- vm: fix case of throwing GeneratorExit type into yield-from
- runtime: remove nlr protection when calling __next__ in mp_resume
- objtype: support full object model for get/set/delitem special meths
- vm: when VM raises exception put exc obj at beginning of func state
- asmthumb: add wide ldr to handle larger offsets
- asmthumb: clean up asm_thumb_bl_ind to use new optimised ldr helper
- asmthumb: extend asm entry/exit to handle stack larger than 508 bytes
- asmx86: comment out unused asm_x86_nop to prevent compiler warnings
- asmx64: extend asm_x64_mov_reg_pcrel to accept high registers
- asmxtensa: use proper calculation for const table offset
- emitnative: reorder native state on C stack so nlr_buf_t is first
- emitnative: implement yield and yield-from in native emitter
- runtime: use mp_import_name to implement tail of mp_import_from
- runtime: remove comment in mp_import_name about level being 0
- obj.h: use uint64_t instead of mp_int_t in repr-D MP_OBJ_IS_x macros
- emitnative: clean up unused macro and forward function declarations
- asmx64: change stack management to reference locals by rsp not rbp
- asmx64: change indirect calls to load fun ptr from the native table
- asmx86: change stack management to reference locals by esp not ebp
- asmx86: change indirect calls to load fun ptr from the native table
- emitnative: load native fun table ptr from const table for all archs
- asmarm: simplify asm_arm_bl_ind to only load via index, not literal
- asmthumb: remove unused fun_ptr arg from asm_thumb_bl_ind function
- emitnative: remove unused ptr argument from ASM_CALL_IND macro
- emitnative: consolidate use of stacked immediate values to one func
- emitnative: simplify viper mode handling in emit_native_import_name
- emitnative: push internal None rather than const obj where possible
- emitnative: put None/False/True in global native const table
- objtype: remove comment about catching exc from user __getattr__
- objstr: make str.count() method configurable
- objmodule: implement PEP 562's __getattr__ for modules
- py.mk: when building axtls use -Wno-all to prevent all warnings
- compile: fix case of eager implicit conversion of local to nonlocal
- compile: remove unneeded variable from global/nonlocal stmt helpers
- scope: optimise scope_find_or_add_id to not need "added" arg
- runtime: fix qstr assumptions when handling "import *"
- unicode: fix check for valid utf8 being stricter about contn chars
- py.mk: fix broken Gmane URL
- add option to reduce GC stack integer size to save RAM
- objboundmeth: support loading generic attrs from the method
- obj: add support for __int__ special method
- objexcept: use macros to make offsets in emergency exc buf clearer
- objexcept: make sure mp_obj_new_exception_msg doesn't copy/format msg
- objdict: make .fromkeys() method configurable
- bc: fix calculation of opcode size for opcodes with map caching
- qstr: put a lower bound on new qstr pool allocation
- objarray: introduce "memview_offset" alias for "free" field of object
- gc: adjust gc_alloc() signature to be able to accept multiple flags
- mpconfig: move MICROPY_VERSION macros to static ones in mpconfig.h
- runtime: unlock the GIL in mp_deinit function
- get optional VM stack overflow check compiling and working again
- fix location of VM returned exception in invalid opcode and comments
- modio: make iobase_singleton object const so it goes in ROM
- obj.h: explicitly cast args to uint32_t in MP_OBJ_FUN_MAKE_SIG

extmod:
- modlwip: update to work with lwIP v2.0
- modlwip: set POLLHUP flag for sockets that are new
- modlwip: allow to compile with MICROPY_PY_LWIP disabled
- modussl_mbedtls: populate sock member right away in wrap_socket
- modussl_mbedtls: use mbedtls_entropy_func for CTR-DRBG entropy
- vfs: use u_rom_obj properly in argument structures
- vfs_fat: rename FileIO/TextIO types to mp_type_vfs_fat_XXX
- add VfsPosix filesystem component
- vfs: add fast path for stating VfsPosix filesystem
- vfs: introduce a C-level VFS protocol, with fast import_stat
- moduhashlib: prefix all Python methods and objects with uhashlib
- moduhashlib: reorder funcs so that they are grouped by hash type
- moduhashlib: allow to disable the sha256 class
- moduhashlib: allow using the sha256 implementation of mbedTLS
- moduhashlib: make function objects STATIC
- uos_dupterm: use native C stream methods on dupterm object
- modussl_axtls: fix __del__ to point to mp_stream_close_obj
- vfs_fat_diskio: factor disk ioctl code to reduce code size
- update to use new mp_get_stream helper
- moducryptolib: add ucryptolib module with crypto functions
- moducryptolib: optionally export MODE_* constants to Python
- moducryptolib: refactor functions for clean interface with axTLS
- moducryptolib: add an mbedTLS implementation for this module
- moducryptolib: prefix all Python methods/objects with ucryptolib
- moducryptolib: shorten exception messages to reduce code size
- moducryptolib: don't include arpa/inet.h, it's not needed
- modure: add match.groups() method, and tests
- modure: add match.span(), start() and end() methods, and tests
- modure: add ure.sub() function and method, and tests
- vfs: support opening a file descriptor (int) with VfsPosix
- fix to support compiling with object representation D
- vfs_posix: support ilistdir with no (or empty) argument
- vfs_posix: use DTTOIF if available to convert type in ilistdir
- modlwip: deregister all lwIP callbacks when closing a socket
- modussl: support polling in ussl objects by passing through ioctl
- modbtree: update to work with new mp_stream_posix_XXX signatures
- modussl_axtls: use MP_ROM_PTR for objects in allowed args array
- moduhashlib: add md5 implementation, using axTLS
- moduhashlib: use newer message digest API for mbedtls >=2.7.0
- moduhashlib: add md5 implementation using mbedtls
- moductypes: remove BITFIELD from aggregate types enum
- moductypes: accept OrderedDict as a structure description
- modonewire: fix reset timings to match 1-wire specs
- moductypes: make sizeof() accept "layout" parameter
- modlwip: implement TCP listen/accept backlog
- modlwip: fix read-polling of listening socket with a backlog
- moductypes: implement __int__ for PTR
- moductypes: add aliases for native C types

lib:
- lwip: update lwIP to v2.0.3, tag STABLE-2_0_3_RELEASE
- stm32lib: update library to include support for STM32F0 MCUs
- utils/printf: make DEBUG_printf implementation more accessible
- utils: fix to support compiling with object representation D
- utils: expose pyb_set_repl_info function public
- libm_dbl/tanh: make tanh more efficient and handle large numbers
- libm/math: make tanhf more efficient and handle large numbers
- libm/wf_tgamma: fix tgammaf handling of -inf, should return nan
- libm_dbl: add implementation of copysign() for DEBUG builds
- stm32lib: update library to fix issue with filling USB TX FIFO
- libm/math: fix int type in float union, uint64_t should be uint32_t
- libm/math: add implementation of __signbitf, if needed by a port
- utils/pyexec: forcefully unlock the heap if locked and REPL active
- utils: add generic MicroPython IRQ helper functions
- stm32lib: update library to get F413 BOR defs and fix gcc 8 warning

drivers:
- wiznet5k: fix bug with MACRAW socket calculating packet size
- memory/spiflash: move cache buffer to user-provided config
- memory/spiflash: rename functions to indicate they use cache
- memory/spiflash: add functions for direct erase/read/write
- sdcard: change driver to use new block-device protocol
- sdcard: fix bug in computing number of sectors on SD Card
- sdcard: do not release CS during the middle of read operations
- cc3000: use cc3000_time_t instead of time_t for custom typedef
- display/lcd160cr.py: in fast_spi, send command before flushing
- sdcard: in test use os.umount and machine module instead of pyb
- sdcard: remove debugging print statement in ioctl method
- dht: allow open-drain-high call to be DHT specific if needed

tools:
- pydfu.py: increase download packet size to full 2048 bytes
- pydfu.py: add support for multiple memory segments
- pydfu.py: use getfullargspec instead of getargspec for newer pyusb
- pydfu.py: workaround stdio flush error on Windows with Python 3.6
- pydfu.py: improve DFU reset, and auto-detect USB transfer size
- mpy-tool.py: support freezing of floats in obj representation D
- mpy-tool.py: put frozen bignum digit data in ROM, not in RAM
- mpy-tool.py: set sane initial dynamic qstr pool size with frozen mods
- mpy-tool.py: fix calc of opcode size for opcodes with map caching
- mpy-tool.py: fix build error when no qstrs present in frozen mpy
- dfu.py: pad image data to 8 byte alignment to support L476
- pyboard.py: run exec: command as a string
- pyboard.py: change base class of PyboardError to Exception
- pyboard.py: in TelnetToSerial.close replace try/except with if

tests:
- basics/special_methods2: enable some additional tests that work
- add some tests for bigint hash, float hash and float parsing
- extmod: add test for importing a script from a user VFS
- extmod: remove conditional import of uos_vfs, it no longer exists
- pyb: make i2c and pyb1 pyboard tests run again
- io: add simple IOBase test
- extmod: add test for VFS and user-defined filesystem and files
- unix/extra_coverage: don't test stream objs with NULL write fun
- extmod/ujson_dump.py: add test for dump to non-stream object
- extmod: add test for ujson.dump writing to a user IOBase object
- import: add test for importing invalid .mpy file
- add tests using "file" argument in print and sys.print_exception
- extmod/ucryptolib*: add tests for ucryptolib module
- extmod/ucryptolib*: add into and inplace tests for ucryptolib
- basics/namedtuple*: import ucollections first
- move non-filesystem io tests to basics dir with io_ prefix
- improve feature detection for VFS
- run-tests: add nrf target
- run-tests: improve crash reporting when running on remote targets
- extmod/ujson_dump_iobase.py: return number of bytes written
- make tests work on targets without float support
- micropython/viper_cond: add test for large int as bool
- run-tests: enable bool1.py test with native emitter
- micropython: add tests for try and with blocks under native/viper
- basics/set_pop.py: sort set before printing for consistent output
- basics/int_big_error.py: use bytearray to test for int overflow
- modify tests that print repr of an exception with 1 arg
- basics: provide .exp files for generator tests that fail PEP479
- run-tests: enable native tests for unwinding jumps
- basics: add more tests for return within try-finally
- basics: add test cases for context manager raising in enter/exit
- float/cmath_fun.py: fix truncation of small real part of complex
- float: test -inf and some larger values for special math funcs
- remove pyboard.py symlink and instead import from ../tools
- extmod/uhashlib_md5: add coverage tests for MD5 algorithm
- float/float_parse.py: add tests for accuracy of small decimals
- cpydiff: add case for difference in behaviour of bytes.format()
- micropython: test loading const objs in native and viper funcs
- basics: split out gen throw tests from yield-from-throw tests
- run-tests: enabled native tests that pass now that yield works
- unix/ffi_float: skip if strtof() is not available
- uselect_poll_basic: add basic test for uselect.poll invariants
- uctypes_sizeof_od: test for using OrderedDict as struct descriptor
- basics/class_getattr: remove invalid test for __getattribute__
- make bytes/str.count() tests skippable
- extmod/uctypes_sizeof_layout: test for sizeof of different layout
- import: add .exp file for module_getattr.py to not require Py 3.7
- cmdline/cmd_showbc.py: fix test to explicitly declare nonlocal
- extmod: skip uselect test when CPython doesn't have poll()
- import_long_dyn: test for "import *" of a long dynamic name
- io: update tests to use uos.remove() instead of uos.unlink()
- basics/special_methods: add testcases for __int__
- extmod/uctypes_ptr_le: test int() operation on a pointer field
- extmod/uctypes_error: add test for unsupported unary op
- run-tests: make .exp and .out file names unique by prefixing with dir

mpy-cross:
- make build independent of extmod directory
- Makefile: also undefine MICROPY_FORCE_32BIT and CROSS_COMPILE

minimal port:
- main: allow to compile without GC enabled

unix port:
- support MICROPY_VFS_POSIX and enable it in coverage build
- moduos_vfs: add missing uos functions from traditional uos module
- mpconfigport.h: enable MICROPY_PY_UCRYPTOLIB
- mpconfigport_coverage: enable ure groups, span, start, end and sub
- modos: convert dir-type to stat-type for file type in ilistdir
- use MP_STREAM_GET_FILENO to allow uselect to poll general objects
- Makefile: coverage: Explicitly build "axtls" too
- Makefile: enable ussl module with nanbox build
- Makefile: remove building of libaxtls.a which is no longer needed
- Makefile: build libffi inside $BUILD
- mpconfigport_coverage.h: enable uhashlib.md5
- modos: include extmod/vfs.h for MP_S_IFDIR, etc
- modjni: update .getiter signature to include mp_obj_iter_buf_t*
- modjni: get building under coverage and nanbox builds
- mpconfigport.h: enable MICROPY_PY_UHASHLIB_MD5 for uhashlib.md5
- moduselect: raise OSError(ENOENT) if obj to modify is not in poller
- modusocket: initial implementation of socket.settimeout()
- modusocket: finish socket.settimeout() implementation
- modffi: add support for "q"/"Q" specs (int64_t/uint64_t)
- Makefile: allow to override/omit pthread lib name
- modos: rename unlink to remove to be consistent with other ports
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable uio.IOBase
- call gc_sweep_all() when doing a soft reset

windows port:
- make printing of debugging info work out of the box
- msvc: support custom compiler for header generation
- msvc: implement file/directory type query
- remove remaining traces of old GNU readline support

stm32 port:
- usbd_conf.h: remove unused macros and clean up header file
- usbd_conf: changes files to unix line endings and apply styling
- usbdev: convert files to unix line endings
- usbdev: remove unused RxState variable, and unused struct
- usbdev: be honest about data not being written to HID endpoint
- usbd_hid_interface: address possible race condition vs. interrupt
- i2c: add new hardware I2C driver for F4 MCUs
- machine_i2c: use new F4 hardware I2C driver for machine.I2C class
- accel: switch pyb.Accel to use new C-level I2C API
- modpyb: introduce MICROPY_PY_PYB_LEGACY config option for pyb mod
- pyb_i2c: put pyb.I2C under MICROPY_PY_PYB_LEGACY setting
- modpyb: remove unused includes and clean up comments
- usb: use usbd_cdc_itf_t pointer directly in USB_VCP class
- usb: combine CDC lower-layer and interface state into one struct
- usb: combine HID lower-layer and interface state into one struct
- usb: make CDC endpoint definitions private to core usbdev driver
- usb: change CDC tx/rx funcs to take CDC state, not usbdev state
- usb: change HID report funcs to take HID state, not usbdev state
- usb: add ability to have 2x VCP interfaces on the one USB device
- usb: initialise cdc variable to prevent compiler warnings
- enable UART7/8 on F4 series that have these peripherals
- add support for STM32L496 MCU
- boards: add board ld and af.csv files for STM32L496 MCU
- boards: add config files for new board, STM32L496GDISC
- rtc: don't try to set SubSeconds value on RTC
- integrate lwIP as implementation of usocket module
- rng: use Yasmarang for rng_get() if MCU doesn't have HW RNG
- remove unneeded HTML release notes from usbdev and usbhost dirs
- add low-level hardware I2C slave driver
- add new component, the mboot bootloader
- allow to have no storage support if there are no block devices
- add support for Cortex-M0 CPUs
- timer: make timer_get_source_freq more efficient by using regs
- allow a board to disable MICROPY_VFS_FAT
- boards: add startup_stm32f0.s for STM32F0 MCUs
- add support for STM32F0 MCUs
- boards: add alt-func CSV list and linker script for STM32F091
- boards: add NUCLEO_F091RC board configuration files
- README: update to include STM32F0 in list of supported MCUs
- boards: split combined alt-func labels and fix some other errors
- boards: ensure USB OTG power is off for NUCLEO_F767ZI
- flash: increase H7 flash size to full 2MiB
- modnetwork: don't take netif's down when network is deinited
- modnetwork: change base entry of NIC object from type to base
- modnetwork: provide generic implementation of ifconfig method
- add network driver for Wiznet5k using MACRAW mode and lwIP
- modnetwork: fix arg indexing in generic ifconfig method
- mpconfigport.h: enable DELATTR_SETATTR and BUILTINS_NOTIMPLEMENTED
- mboot: increase USB rx_buf and DFU buf sizes to full 2048 bytes
- Makefile: rebuild all qstrs when any board configuration changes
- boards/STM32L476DISC: update SPI flash config for cache change
- timer: support TIM1 on F0 MCUs
- i2c: fix num_acks calculation in i2c_write for F0 and F7 MCU's
- i2cslave: fix ordering of event callbacks in slave IRQ handler
- mboot: adjust user-reset-mode timeout so it ends with mode=1
- boards/stm32f091_af.csv: split labels that are multiple funcs
- boards/NUCLEO_F091RC: add Arduino-named pins and rename CPU pins
- can: use MP_OBJ_ARRAY_TYPECODE_FLAG_RW where appropriate
- spi: fix SPI driver so it can send/recv more than 65535 bytes
- mboot: define constants for reset mode cycling and timeout
- boards/NUCLEO_F091RC: fix TICK_INT_PRIORITY so it is highest prio
- qspi: don't require data reads and writes to be a multiple of 4
- mboot: add support for erase/read/write of external SPI flash
- boards: add .ld and af.csv files for STM32F722
- modnetwork: fix query of DNS IP address in ifconfig()
- mboot: fix bug with invalid memory access of USB state
- mboot: only compile in code for the USB periph that is being used
- mboot: always use a flash latency of 1WS to match 48MHz HCLK
- access dict map directly instead of using helper function
- support compiling with object representation D
- fatfs_port: fix bug when MICROPY_HW_ENABLE_RTC not enabled
- timer: use enum for indexing keyword arg in pyb_timer_init_helper
- timer: add tick_hz arg to Timer constructor and init method
- mphalport: make mp_hal_stdin_rx_chr/stdout_tx_strn weakly linked
- flashbdev: fix bug with L4 block cache, dereferencing block size
- add method for statically configuring pin alternate function
- sdcard: use mp_hal_pin_config_alt_static to configure SD card pins
- sdram: add SDRAM driver from OpenMV project
- sdram: integrate SDRAM driver into rest of code
- sdram: on F7 MCUs enable MPU on external SDRAM
- boards/STM32F429DISC: enable onboard SDRAM
- sdcard: get SDMMC alt func macro names working with F4,F7,H7 MCUs
- Makefile: use -Wno-attributes for ll_usb.c HAL source file
- rtc: get rtc.wakeup working on F0 MCUs
- modmachine: get machine.sleep working on F0 MCUs
- extint.h: use correct EXTI lines for RTC interrupts
- modmachine: get machine.sleep working on L4 MCUs
- adc: disable VBAT in read channel helper function
- adc: fix ADC reading on F0 MCUs to only sample a single channel
- spi: round up prescaler calc to never exceed requested baudrate
- sdram: allow additional config by a board, and tune MPU settings
- boards/STM32F429DISC: add burst len and autorefresh to SDRAM cfg
- boards/STM32F7DISC: enable onboard SDRAM
- spi: split out pyb.SPI and machine.SPI bindings to their own files
- spi: add implementation of low-level SPI protocol
- mboot/main: use correct formula for DFU download address
- Makefile: allow external BOARD_DIR directory to be specified
- boards/STM32L476DISC: enable external RTC xtal to get RTC working
- for MCUs that have PLLSAI allow to set SYSCLK at 2MHz increments
- dma: pass DMA direction as parameter to dma_init not in cfg struct
- dma: reinitialise the DMA if the direction changed on the channel
- sdcard: use only a single DMA stream for both SDIO TX/RX
- sdcard: move temporary DMA state from BSS to stack
- spi: be sure to set all SPI config values in SPI proto init
- change flash IRQ priority from 2 to 6 to prevent preemption
- flashbdev: protect flash writes from cache flushing and USB MSC
- sdcard: fully reset SDMMC periph before calling HAL DMA functions
- dma: get DMA working on F0 MCUs
- sdram: add support for 32-bit wide data bus and 256MB in MPU cfg
- boards/STM32F769DISC: add optional support for external SDRAM
- add support for STM32F765xx MCUs
- Makefile: include copysign.c in double precision float builds
- adc: fix ADC calibration scale for L4 MCUs, they use 3.0V
- adc: increase sample time for internal sensors on L4 MCUs
- dcmi: add F4/F7/H7 hal files and dma definitions for DCMI periph
- uart: add support for USART3-8 on F0 MCUs
- boards/NUCLEO_F091RC: enable USART3-8 with default pins
- modmachine: re-enable PLLSAI[1] after waking from stop mode
- powerctrl: move function to set SYSCLK into new powerctrl file
- powerctrl: fix configuring APB1/APB2 frequency when AHB also set
- powerctrl: factor code to set RCC PLL and use it in startup
- powerctrl: factor code that configures PLLSAI on F7 MCUs
- powerctrl: optimise passing of default values to set_sysclk
- powerctrl: don't configure clocks if already at desired frequency
- usbd_conf: allocate enough space in USB HS TX FIFO for CDC packet
- mpconfigport.h: enable math.factorial, optimised version
- main: add configuration macros for board to set heap start/end
- usbd_cdc_interface: handle disconnect IRQ to set VCP disconnected
- usbd_cdc_interface: refactor USB CDC tx code to not use SOF IRQ
- spi: fix calculation of SPI clock source on H7 MCUs
- boards/stm32h743.ld: fix total flash size, should be 2048k
- system_stm32: introduce configuration defines for PLL3 settings
- adc: add ADC auto-calibration for L4 MCUs
- flashbdev: add missing include for irq.h
- servo: only initialise TIM5 if it is needed, to save power
- usb: fully deinitialise USB periph when it is deactivated
- powerctrl: move (deep)sleep funcs from modmachine.c to powerctrl.c
- powerctrl: disable IRQs during stop mode to allow reconfig on wake
- boards/STM32F429DISC: enable UART as secondary REPL
- uart: always show the flow setting when printing a UART object
- mboot: provide led_state_all function to reduce code size
- mboot: add support for 4th board LED
- boards: add configuration for putting mboot on PYBv1.x
- mboot: add documentation for using mboot on PYBv1.x
- powerctrl: add support for standby mode on L4 MCUs
- uart: add rxbuf keyword arg to UART constructor and init method
- boards: add STM32L432KC chip configuration files
- add peripheral support for STM32L432
- boards: add NUCLEO_L432KC board configuration files
- split out UART Python bindings from uart.c to machine_uart.c
- uart: factor out code from machine_uart.c that computes baudrate
- uart: rework uart_get_baudrate so it doesn't need a UART handle
- uart: factor out code to set RX buffer to function uart_set_rxbuf
- uart: remove HAL's UART_HandleTypeDef from UART object struct
- uart: simplify deinit of UART, no need to call HAL
- uart: for UART init, pass in params directly, not via HAL struct
- uart: move config of char_width/char_mask to uart.c
- uart: add ability to have a static built-in UART object
- extint: use correct EXTI channels on H7 MCUs for RTC events
- adc: fix calibrated volt/temp readings on H7 by using 16bit scale
- adc: increase ADC sampling time for internal sources on H7 MCUs
- adc: support 16-bit ADC configuration on H7 MCUs
- boards: allow OpenOCD stm_flash procedure to accept single FW img
- boards/NUCLEO_L432KC: specify L4 OpenOCD config file for this MCU
- main: add board config option to enable/disable mounting SD card
- implement UART.irq() method with initial support for RX idle IRQ
- uart: fix uart_rx_any in case of no buffer to return 0 or 1
- uart: always enable global UART IRQ handler on init
- uart: clear overrun error flag after reading RX data register
- uart: make sure user IRQs are handled even with a keyboard intr
- modmachine: fix reset_cause to correctly give DEEPSLEEP on L4 MCU
- sdcard: properly reset SD periph when SDMMC2 is used on H7 MCUs
- wdt: make singleton WDT object const so it goes in ROM
- main: make thread and FS state static and exclude when not needed
- use MICROPY_GC_STACK_ENTRY_TYPE to save some RAM
- .gitattributes: remove special text handling of stm32 usbdev files
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable descriptors
- enable uio.IOBase
- enable ure.sub()
- call gc_sweep_all() when doing a soft reset

cc3200 port:
- mods: include stream.h to get definition of mp_stream_p_t
- mods: access dict map directly instead of using helper func
- use MICROPY_GC_STACK_ENTRY_TYPE to save some RAM

esp8266 port:
- mpconfigport.h: add some weak links to common Python modules
- modnetwork: return empty str for hostname if STA is inactive
- modnetwork: raise ValueError when getting invalid WLAN id
- modmachine: allow I2C and SPI to be configured out of the build
- change UART(0) to attach to REPL via uos.dupterm interface
- modules/ntptime.py: remove print of newly-set time
- mpconfigport.h: enable ucryptolib module for standard build
- esp8266_common.ld: put mp_keyboard_interrupt in iRAM
- modesp: run ets_loop_iter before/after doing flash erase/write
- let machine.WDT trigger the software WDT if obj is not fed
- Makefile: remove build of libaxtls.a and add back tuned config
- main: increase heap by 2kb, now that axtls rodata is in ROM
- remove scanning of GC pointers in native code block
- ets_alt_task: process idle callback if no other events occurred
- modnetwork: automatically do radio sleep if no interface active
- modnetwork: wait for iface to go down before forcing power mgmt
- machine_uart: add rxbuf keyword arg to UART constructor/init
- main: activate UART(0) on dupterm for REPL before boot.py runs
- esp_mphal: provide mp_hal_pin_od_high_dht so DHT works reliably
- implement high-res timers using new tick_hz argument
- use MICROPY_GC_STACK_ENTRY_TYPE to save some RAM
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable descriptors
- enable uio.IOBase
- enable ure.sub()
- call gc_sweep_all() when doing a soft reset, cleans up sockets

esp32 port:
- update to latest ESP IDF version
- modnetwork: fix STA/AP activate/deactivate for new IDF API
- Makefile: update to latest ESP IDF version
- esp32.custom_common.ld: put soc code in iram0
- silence ESP-IDF log messages when in raw REPL mode
- Makefile: extract common C & C++ flags for consistent compilation
- add support for building with external SPI RAM
- modnetwork: fix isconnected() when using static IP config
- remove port-specific uhashlib implementation and use common one
- fatfs_port: implement get_fattime so FAT files have a timestamp
- update to latest ESP IDF
- modules: include umqtt library in frozen modules
- mpconfigport.h: enable ucryptolib module
- allow to build with uPy floats disabled
- reduce latency for handling of scheduled Python callbacks
- modnetwork: add support for bssid parameter in WLAN.connect()
- implement WLAN.status() return codes
- modesp32: add raw temperature reading to esp32 module
- modesp32: use MP_ROM_QSTR and MP_ROM_PTR in const locals dict
- modnetwork: add network.(W)LAN.ifconfig('dhcp') support
- update to latest ESP IDF
- fix int overflow in machine.sleep/deepsleep functions
- machine_rtc: fix locals dict entry, init qstr points to init meth
- modesp32: add hall_sensor() function
- network_ppp: add PPPoS functionality
- mpthreadport: prevent deadlocks when deleting all threads
- allocate task TCB and stack from system heap not uPy heap
- machine_uart: add txbuf/rxbuf keyword args to UART construct/init
- machine_uart: implement UART.sendbreak() method
- machine_pwm: support higher PWM freq by auto-scaling timer res
- machine_pwm: on deinit stop routing PWM signal to the pin
- modmachine: enable machine.sleep() now that the IDF supports it
- mphalport: when tx'ing to REPL only release GIL if many chars sent
- modsocket: for socket read only release GIL if socket would block
- machine_pin: add Pin.off() and Pin.on() methods
- Makefile: use system provided math library rather than uPy one
- modules/neopixel.py: change NeoPixel to different default timings
- machine_hw_spi: use separate DMA channels for HSPI and VSPI
- machine_hw_spi: make HW SPI objects statically allocated
- implement high-res timers using new tick_hz argument
- enable MICROPY_PY_BUILTINS_ROUND_INT
- enable descriptors
- enable uio.IOBase
- enable ure.sub()
- call gc_sweep_all() when doing a soft reset

nrf port:
- add new port to Nordic nRF5x MCUs
- align help.c builtin help text to use correct type
- add WT51822-S4AT board
- use --gc-sections to reduce code size
- add compile switch to disable VFS
- enable Link-time optimizations (LTO)
- boards/arduino_primo: add missing hal_rng config used by random mod
- implement NVMC HAL
- disable FAT/VFS by default
- hal/nvmc: remove pre-compiler error thrown in nvmc.h, if on nrf52
- hal/hal_nvmc: fix non-SD code
- boards: update linker scripts
- add micro:bit filesystem
- drivers/bluetooth/ble_drv: don't handle non-events
- modules/uos/microbitfs: make OSError numeric
- main: run boot.py and main.py on startup
- use micropython libm to save flash
- main: add ampy support
- drivers/bluetooth: start advertising after disconnect
- update usage of mp_obj_new_str by removing last parameter
- remove default FROZEN_MPY_DIR
- option to enable Ctrl-C in NUS console
- boards/microbit: add copy of microbit display and image files
- boards/microbit: add copy of microbit font type from microbit-dal
- boards/microbit: rename display/image files from .cpp to .c ext
- boards/microbit: update board modules from C++ to C-code
- boards/microbit: add framework updates to build micro:bit modules
- boards/microbit: attempt to get working display/images without FP
- boards/microbit: add modmicrobit.h to expose module init function
- boards/microbit: include modmicrobit.h in board_modules.h
- drivers/softpwm: rename init function to softpwm_init0
- drivers/ticker: rework ticker functions for microbit display/music
- boards/microbit: update to work with new ticker code
- modules/music: remove init of softpwm/ticker upon music module load
- update main.c to init relevant board drivers, if enabled
- boards/microbit: move microbit target to custom linker script
- boards/microbit/modules: fix tabbing in modmicrobit.c
- boards/microbit: add temperature back to microbit module
- boards/microbit: update docs on top level tick low pri callback
- change board module header from board_modules.h to boardmodules.h
- add if-def around inclusion of nrf_sdm.h in main
- boards/microbit: enable music, display, image, microbit module
- drivers/bluetooth: reset evt_len to size of static buffer each iter
- add support for s132 v5.0.0 bluetooth stack (#139)
- change PYB prefix to MPY
- only search for frozen files if FROZEN_MPY_DIR is set
- mpconfigport: reduce GC stack size for nrf51
- modules/machine/pin: disable pin debug by default
- boards/common.ld: avoid overflowing the .text region
- drivers/ble_drv: fixing sd_ble_enable bug for SD s132 v.2.0.1
- make machine.UART optional
- fix stack size in ld script and enable MICROPY_STACK_CHECK
- improve include of boardmodules.mk
- make LTO configurable via Makefile flag
- boards/microbit/modules: initialize variable in microbit_sleep
- replace custom-HAL with nrfx-HAL
- fix NUS console when using boot.py or main.py
- Makefile: fix .PHONY target
- enable -g flag by default
- make linker scripts more modular
- remove port member from Pin object
- modules/machine/pin: add support for IRQ on Pin's
- modules/machine/spi: sPIM (EasyDMA) backend for nrf52x
- drivers/bluetooth/ble_drv: increase max transfers in progress
- gccollect: use the SP register instead of MSP
- boards: remove unused defines from board config headers
- boards/wt51822_s4at: fixes after nrfx and Pin IRQ introduction
- modules/random: rename port config for RNG
- modules: align method to resolve pin object
- adc: allow for external use of new and value read function
- spi: allow for external use of new and transfer function
- return immediatly from mp_hal_delay_us if 0us is given
- modules/machine/adc: fix to make adc.c compile for nrf51 targets
- bluetooth: fixes for s132 v5 BLE stack
- Makefile: use "standard" GCC -fshort-enums instead of --short-enums
- Makefile: remove -fstack-usage
- Makefile: use C11 instead of Gnu99
- Makefile: refine dead-code elimination parameters
- modules/machine/adc: don't compare -1 to an unsigned number
- modules/uos/microbitfs: fix errno defines
- modules/uos/microbitfs: remove unused uos_mbfs_mount
- enable micro:bit FS by default
- boards/feather52: move phony targets to main Makefile
- modules/machine/spi: move enable-guard to prevent wrong includes
- nrfx_config: move back nrf52832 to use non-EasyDMA SPI
- move pyb module to boards module
- add support for reading output pin state
- generalize feather52 target
- bluetooth: add support for s132/s140 v6, remove s132 v2/3/5
- boards: check for stack/heap size using an assert
- quick-fix on const objects with open array dimension in objtuples
- bluetooth: replace BLE REPL (WebBluetooth) URL
- add explicit make flag for oofatfs
- compile nlr objects with -fno-lto flag
- upgrade to nrfx 1.1.0
- drivers: add license text to ticker.h and softpwm.h
- use mp_raise_ValueError instead of nlr_raise(...)
- include $(SRC_MOD) in the build
- Makefile: make sure dependencies for pins_gen.c are correct
- properly use (void) instead of () for function definitions
- boards/microbit: use MICROPY_PY_BUILTINS_FLOAT to detect FP support
- update nrfjprog links to allow to download any version
- drivers/flash: fix incorrect page alignment check
- uos: add mbfs __enter__ and __exit__ handlers
- enable all PWM, RTC and Timer instances for nrf52840
- correct index checking of ADC/PWM/RTCounter instances
- use separate config for each PWM instance
- uart: remove unused UART.char_width field
- uart: fix UART.writechar() to write just 1 byte
- bluetooth: set GAP_ADV_MAX_SIZE to 31 (s132/s140)
- bluetooth: update BLE stack download script

pic16bit port:
- update to compile with latest xc16 v1.35 compiler

teensy port:
- add own uart.h to not rely on stm32's version of the file

zephyr port:
- README: hint about existence of qemu_x86_nommu
- main: after builtin testsuite, drop to REPL
- mpconfigport.h: enable uhashlib and ubinascii modules
- modzsensor: zephyr sensor subsystem bindings
- prj_base.conf: enable DHCP and group static IPs together
- add prj_disco_l475_iot1.conf with sensor drivers
- Makefile: add kobj_types_h_target to Z_EXPORTS
- prj_base.conf: remove outdated CONFIG_NET_NBUF_RX_COUNT option
- prj_qemu_x86.conf: remove outdated CONFIG_RAM_SIZE
- rename CONFIG_CONSOLE_PULL to CONFIG_CONSOLE_SUBSYS
- prj_base.conf: update for net_config subsys refactor
- CMakeLists: update for latest Zephyr CMake usage refactorings

docs:
- library: add documentation for ucollections.deque
- ucryptolib: add docs for new ucryptolib module
- usocket: getaddrinfo: describe af/type/proto optional params
- usocket: minor fixes to grammar of getaddrinfo
- uos: make it clear that block device block_num param is an index
- ure: document sub(), groups(), span(), start() and end()
- ure: document some more supported regex operators
- pyboard: for latex build, use smaller quickref jpg, and no gifs
- library: remove "only" directive from all pyb module docs
- library/machine.UART: remove conditional docs for wipy port
- library/machine: remove conditional docs for wake_reason function
- library/machine: remove conditional docs for rng function
- library/index: remove all conditionals from library index
- library/index: add hint about using help('modules') for discovery
- reference/index: remove conditional for inline asm docs
- library/machine: remove conditionals in machine class index
- move WiPy specific Timer class to separate doc file
- library/machine.I2C.rst: clarify availability of primitive I2C ops
- library/machine.UART.rst: specify optional txbuf and rxbuf args
- library/pyb: add deprecation warning for mount and old block proto
- pyboard: fix to use Sphinx style for internal/external links
- library/machine.SPI: add note about baudrate imprecision
- library/network: move specific network classes to their own file
- library/network: make AbstractNIC methods layout correctly
- unify all the ports into one set of documentation
- remove sphinx_selective_exclude, it's no longer used
- wipy: fix links to network.Server, and markup for boot.py
- uselect: describe more aspects of poll.register/modify behavior
- machine.Pin: add note regarding irq handler argument
- machine.Pin: document "hard" argument of Pin.irq method
- uio: document StringIO/BytesIO(alloc_size) constructors
- library/uctypes: add examples and make general updates
- conf.py: use https for intersphinx link to docs.python.org
- ure: fully describe supported syntax subset, add example
- differences: clarify the differences are against Python 3.4
- add initial docs for esp32 port, including quick-ref and general
- library: add documentation for esp32 module

travis:
- install explicit version of urllib3 for coveralls
- use build stages and parallel jobs under Travis CI
- add nrf port to Travis CI build

examples:
- embedding: add code markup and fix typo in README.md
- embedding: fix reference to freed memory, lexer src name
- embedding: fix hard-coded MP_QSTR_ value
- unix/ffi_example: clean up and update the ffi example

README:
- update list of ports to include esp32 and nrf
- remove references to "make axtls", it's no longer needed
- remove text about selecting different ports in the docs