> My suggestion would be to check the co-operative scheduler included and
> explained in this free ebook
> http://www.tte-systems.com/books/pttes
>
> The scheduler is written in C and can be easily ported to any mcu, all
> you need to change is the interrupt handler to match your device.
>
> I doubt that your project needs a pre-emptive RTOS, I'm not even sure if
> you actually need any OS.
>
> Alex

I have that book! Unfortunately, I have the hardback costly version... Free is so much better!

I used the scheduler for a PIC project several years ago and it worked out fine.

If individual tasks can be broken up into tiny morsels and the code written as a state machine versus a time consuming loop, cooperative multitasking works well. Loops like the following don't work well for this type of scheduling:

while (<wait for some condition>) {
;
}
<do something>

but something like this will:

void Task1(void)
{
switch(state) {
case WAIT: if (<some condition>) state = DO; break;
case DO: <do something>; state = WAIT; break;
}
}

In the SuperLoop just call Task1 from time to time.

while (1) { // SuperLoop
Task1();
...
...
}

Obviously, there are a bunch of details missing...

Richard Start a New Thread