> while (TRUE)
>    {
>     if (DO_IT_NOW)
>       pid_calculations();
>    code_a();
>    code_b();
>    code_c();
>    code_d();
>    }

Sorry, I did not look at your code long enough. The standard 'fixed
interval loop' looks more like this:

while( TRUE ){
   while( ! DO_IT_NOW ){}
   pid_calculations();
   code_a();
   code_b();
   code_c();
   code_d();
}

Of course the total excution time must be less than the timer interval.
If not read my previous post.

Wouter van Ooijen

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