scheduler

The simplest C task scheduler for microcontrollers (Arduino)

Write asynchronous code for Arduino! Read my blog post to learn more about why you may want to incorporate async into your microcontroller code including Raspberry Pi Pico (using uasyncio). https://yiweimao.github.io/blog/async_microcontroller/

You only need to know one function and that is run_later which schedules a callback function to be run at a later time. The callback function must be of type void with no arguments.

To create a task that reschedules itself, simply call run_later on itself with a specified wait time. For example, this is how the blink function is written.

void blinkLED(){
    short toggle_delay = 250; // ms
    run_later(blinkLED, toggle_delay);

    pinMode(LED_BUILTIN,OUTPUT);
    digitalWrite(LED_BUILTIN,!digitalRead(LED_BUILTIN));
}

After you call blinkLED, the builtin LED will continue to blink in the background and you will have clock cycles to run other code using run_later.

Run initOS before scheduling any tasks and fill up the scheduler before you run the even loop; for example, within the void setup() block. See the examples folder for a blink and serial sketch using this scheduler.

To run the event loop, end your sketch with

void loop() {
  run();
}

A Note on Other Schedulers

There are other schedulers for Arduino. See a list of five including FreeRTOS and CoopThreads. The closest implementation to what is present here is probably TaskManagerIO.

All of these have more featured APIs if you want more advanced features other than the simplistic run_later call.

YiweiMao/scheduler

scheduler

A Note on Other Schedulers