Bill Couture wrote :

> I found that the PID *HAD* to be in the interrupt, *IN IT'S ENTIRETY*
> (otherwise, the part of the PID that was not in the interrupt had
> to look for it's flag,

No, the main-loop should do the flag-checking that and call the
PIC code when needed.

> and there was no advantage to having ANY of the
> PID in the interrupt).

Maybe...

But...
You also said that you missed bytes on the serial link
sometimes, didn't you ?

That is, as I understand things, becuse you have locked-up
the PIC in the PID-ISR for a to long time (with regard to
the response time needed to not miss anything on the serial
link).


> The background loop has a fair amount of processing (none of it time
> critical), and the jitter associated with getting around to see if
> the PID flag was set could be seen in the mechanical system (and even
> heard!).
>
> Since the PID is in the interrupt, it runs EXACTLY on
> schedule.

But that wasn't the problem, was it ? Was it not the
missed bytes on the serial link that was the problem ?
Anyway, that was what I was trying to address...

Jan-Erik.

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