Hi Greg,

If you know the amount of time for your ISR is 70 msecs, why don't you set
the TMR0 values to interrupt 30 msecs later?  Normally, the TMR0 is
reset/reloaded at the start of an ISR, what I'm suggesting is that you do it
later with a set delay.

myke

----- Original Message -----
From: "Hartung, Greg" <ghartung@ADT.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, August 01, 2001 5:54 PM
Subject: T0CK for slow INT


>    My ISR routine takes a very long time to service.  About 70ms, longer
> than the lowest frequency I can engineer with the dividers on a 20Mhz
> crystal (20m/4/65536=.  I would like to call the ISR on a nice even
> frequency of 10hz so the sampling is easy and intuitive to graph later.
The
> dividers will reduce by up to 65,536, so...  a crystal of 10x? or a 555 of
> 10x? or is there an easier way?  I don't think I can do it the traditional
> way of just interrupting more often and keeping a counter because my ISR
> will skip interrupts on certain iterations.  Olin suggested trimming my
ISR
> code, but everything there needs to get done before the next iteration, so
> that doesn't seem like the solution.
>
>    Greg Hartung
>
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