Arduino based task scheduler/threading functions

ardIf you’ve used the Arduino before then you’ll know that any code you write in the loop() function is executed on every cycle. But what happens when you have code that needs to run at certain intervals? A delay() will just cause that iteration of loop() to hang and pause.

Arduino released a tutorial BlinkWithoutDelay¬†which introduced the concept of checking the “uptime since last boot” and comparing that to make a basic function scheduler.

The code below basically does the same job, except it’s cleaner and easier to manage. This is by no means original, there have been hundreds of productions of this code, this is just one way to go about it.

The naming structure is shown below, instances of the Timer are prefixed with t_FunctionName to indicate this is a timer.

Instead of checking a single variable for the current milliseconds since boot, this will create a new instance of a structure that can be used to store timings for functions. This way you can easily change when to run a certain portion of code without digging through the sketch or remembering which variables contain the correct values.

The loop() portion of the sketch should be kept clean and only be checking the cycles of the functions from the structure. There should be no need to place any program code inside of the loop() function except for these checks.

This should provide the following benefits:

  1. Enable you to run code every [x] milliseconds or [x] seconds.
  2. Structure the program so that you know when code is running and being able to easily change this.
  3. Have a faster running program. e.g. if you know a portion of code is slower and delaying the loop() you can have this run on a larger interval so it isn’t executed as often.

This code is compatible with all versions of the Arduino and most likely other boards where the language is also based on C.