Tip: how do you keep a task from starving?

[philj404]

This comment was part of #15, but it may be helpful to others.

A lot of this is covered by the old CS "Dining Philosophers" problem. It's a fascinating topic and there's a lot you can learn.

There are many ways to solve this problem (each with different tradeoffs). But for busy people who just want to make their LEDs blink without stuttering, here are some starting suggestions:

• Try to move EVERYTHING into a timer task. Delays (and useful code!) in loop() will always slow all timer tasks. The tasks will not run until loop() calls timer.tick(). If you really need some code to run every loop you can use timer.every(0, doItEveryLoop).
• Ideally loop() would only have timer.tick() in it.
• A large task can starve all other tasks while it is running. Try to break a large task in to smaller parts. Part1 can start part2 with timer.at(0, part2). Part2 can start part3, etc.. (Be careful to ensure Part1 does not restart until all the other parts have finished. I forgot to do this once -- I was very confused for a while.)
• If your high-frequency task has a hard deadline, you may want to use timer interrupts. For example if you don't want your scrolling LED display to stutter while logging data, a timer interrupt task could help.
• The arduino-timer library is cooperative -- it waits for a task to finish before searching for another task to run. It does not use any extra hardware resources or get in the way of a hardware timer interrupt task. You should be able to use both arduino-timer and hardware timer interrupts at the same time.
• Consider using buffers to help your task be more tolerant of (short) delays. This can help a task catch up if it ever missed a deadline. For example if a late task checks for Serial data, maybe it can process/consume several data bytes when it finally does have a chance to run.

I hope this helps.

[philj404]

This is a tip which can help you understand how to get arduino-timer to work consistently.