From 7ce15aca15c1f14f7ed084eac3cde37ffa89d183 Mon Sep 17 00:00:00 2001
From: "Mark A. Yoder" <Mark.A.Yoder@Rose-Hulman.edu>
Date: Fri, 25 Aug 2023 16:35:25 -0400
Subject: [PATCH] Added evtest examples
---
intro/blinkLED.rst | 65 ++++++++++++++++++++++++++++++++++++++++++++
intro/buttonEvent.sh | 24 ++++++++++++++++
intro/buttonLED.sh | 21 ++++++++++++++
3 files changed, 110 insertions(+)
create mode 100755 intro/buttonEvent.sh
create mode 100755 intro/buttonLED.sh
diff --git a/intro/blinkLED.rst b/intro/blinkLED.rst
index d995372b..d78e01c5 100644
--- a/intro/blinkLED.rst
+++ b/intro/blinkLED.rst
@@ -306,4 +306,69 @@ Try it for the other LEDs.
This may not work on all Beagles since it depends on which
version of Debian you are running.
+Blinking in response to a button
+---------------------------------
+Some Beagles have a USR button that can be used to control the LEDs.
+You can test the USR button with ``evtest``
+
+.. code-block:: shell-session
+
+ bone:~$ evtest
+ No device specified, trying to scan all of /dev/input/event*
+ Not running as root, no devices may be available.
+ Available devices:
+ /dev/input/event0: tps65219-pwrbutton
+ /dev/input/event1: gpio-keys
+ Select the device event number [0-1]: 1
+
+We want to use ``gpio-keys``, so enter ``1``. Press and release
+the USR button and you'll see:
+
+ .. code-block:: shell-session
+
+ Input driver version is 1.0.1
+ Input device ID: bus 0x19 vendor 0x1 product 0x1 version 0x100
+ Input device name: "gpio-keys"
+ Supported events:
+ Event type 0 (EV_SYN)
+ Event type 1 (EV_KEY)
+ Event code 256 (BTN_0)
+ Key repeat handling:
+ Repeat type 20 (EV_REP)
+ Repeat code 0 (REP_DELAY)
+ Value 250
+ Repeat code 1 (REP_PERIOD)
+ Value 33
+ Properties:
+ Testing ... (interrupt to exit)
+ Event: time 1692994988.305846, type 1 (EV_KEY), code 256 (BTN_0), value 1
+ Event: time 1692994988.305846, -------------- SYN_REPORT ------------
+ Event: time 1692994988.561786, type 1 (EV_KEY), code 256 (BTN_0), value 2
+ Event: time 1692994988.561786, -------------- SYN_REPORT ------------
+ Event: time 1692994988.601883, type 1 (EV_KEY), code 256 (BTN_0), value 2
+ Event: time 1692994988.601883, -------------- SYN_REPORT ------------
+ Event: time 1692994988.641754, type 1 (EV_KEY), code 256 (BTN_0), value 2
+ Event: time 1692994988.641754, -------------- SYN_REPORT ------------
+ Event: time 1692994988.641754, type 1 (EV_KEY), code 256 (BTN_0), value 0
+ Event: time 1692994988.641754, -------------- SYN_REPORT ------------
+ Ctrl+c
+
+The following script uses evtesst to wait for the USR button to be pressed and
+then turns on the LED.
+
+.. literalinclude:: buttonEvent.sh
+ :caption: buttonEvent.sh
+ :linenos:
+
+:download:`buttonEvent.sh<buttonEvent.sh>`
+
+Try running it and pressing the USR button.
+
+The next script polls the USR button and toggles the LED.
+
+.. literalinclude:: buttonLED.sh
+ :caption: buttonLED.sh
+ :linenos:
+
+:download:`buttonLED.sh<buttonLED.sh>`
diff --git a/intro/buttonEvent.sh b/intro/buttonEvent.sh
new file mode 100755
index 00000000..61cba508
--- /dev/null
+++ b/intro/buttonEvent.sh
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+#//////////////////////////////////////
+# buttonEvent.sh
+# Blinks a USR LED when USR button is pressed
+# Waits for a button event
+# Wiring:
+# Setup:
+# See: https://unix.stackexchange.com/questions/428399/how-can-i-run-a-shell-script-on-input-device-event
+#//////////////////////////////////////
+
+device='/dev/input/by-path/platform-gpio-keys-event'
+
+LED="3"
+LEDPATH='/sys/class/leds/beaglebone:green:usr'
+
+key_off='*value 0*'
+ key_on='*value 1*'
+
+evtest --grab "$device" | while read line; do
+ case $line in
+ ($key_off) echo 0 > ${LEDPATH}${LED}/brightness ;;
+ ($key_on) echo 1 > ${LEDPATH}${LED}/brightness ;;
+ esac
+done
diff --git a/intro/buttonLED.sh b/intro/buttonLED.sh
new file mode 100755
index 00000000..f79a2869
--- /dev/null
+++ b/intro/buttonLED.sh
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+#//////////////////////////////////////
+# buttonLED.sh
+# Blinks a USR LED when USR button is pressed
+# Polls the button
+# Wiring:
+# Setup:
+# See:
+#//////////////////////////////////////
+
+LED="3"
+
+BUTTONPATH='/dev/input/by-path/platform-gpio-keys-event'
+LEDPATH='/sys/class/leds/beaglebone:green:usr'
+
+while true ; do
+ # evtest returns 0 if not pressed and a non-0 value if pressed.
+ evtest --query $BUTTONPATH EV_KEY BTN_0
+ echo $? > ${LEDPATH}${LED}/brightness
+ sleep 0.1
+done
--
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