On Mon, Jan 18, 1999 at 06:27:07AM +0100, Gianni wrote:
> Unfortunately I haven't considered the necessary time to serve int. and
> reload TMR0 . So I lose 10usec. every 8msec. = 4.5sec/h (a poor clock!!)

The general solution to this is to add the time constant to TMRO in the interrup
t
routine, rather than storing the value. E.g.

void interrupt tmr0()
{
        TMR0 += -125;
}

Because at the time of overflow, TMR0 has a value of 0, then however many counts
elapse between then and when your interrupt routine runs will be the same as
the value of TMR0 at that time, so adding the reload value will automatically
compensate for the (variable) interrupt service time.


--
Clyde Smith-Stubbs               |            HI-TECH Software
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HI-TECH C: compiling the real world.