Async Tasks
RTIC also supports long-lived tasks which are not tied to any particular interrupt. These must be written as async functions.
✅ Load the stm32-code/standalone-app/src/bin/standalone-rtic-blink.rs file and observe how async tasks can be created.
Why does the code say:
next_blink += BLINK_PERIOD_MS.millis();
Mono::delay_until(next_blink).await;When it could have said:
Mono::delay(BLINK_PERIOD_MS.millis()).await;Answer
There is a small amount of time spent in handling the interrupt, controling the LEDs and doing the logging. With a naive loop, the total time spent would be BLINK_PERIOD_MS, plus a little bit. This would cause the timekeeping to drift over minutes or hours.
By saying “OK, it was X, so now wait until X + BLINK_PERIOD_MS”, the extra time spent on overheads is accounted for and no time slippage should occur.
✅ Run the standalone-rtic-blink program
Do you observe the timestamps in the log messages? Is it drifting at all?
✅ Edit the file to adjust the delays and which LED is (or which LEDs are) being blinked, and run to check your changes.