read_counter.rst

Read hardware counter example

Code

start_counter();
while : read_counter() < 200000000 {
    digital_write(4, true);
}
stop_counter();

• Following code works on PocketBeagle, to use on other boards, please change the pins accordingly.

Explaination

Since, PRU's hardware counter works at 200 MHz, it counts upto 2 x 108 cycles in 1 second. So, this can be reliably used to count time without using delay, as we can find exactly how much time 1 cycle takes.

2 x 108 cycles/second.

1 Cycles = 0.5 x 10-8 seconds.

So, it can be used to count how many cycles have passed since, say we received a high input on pin 3. start_counter starts the counter, and read_counter reads the current state of the counter, and stop_counter stops the counter.