Previous post went out B4 I'd finished ;-( grrrr

Your punctuation led me (incorrectly) to read that you
were aiming for a target of 32 point 768 seconds. Now
that I look closer, I see that you wrote 32 768, not 32.768,
an error of 0.0153% or 15,260ppm

> If variable X is set to 32 768 seconds, I would actually
> expect slightly more (given a few GOTO routines etc. X
> 32768), but I am actually seeing about 5 seconds less"

A TMR0 IRQ, by its very nature, does not rely on anything
except its own counting. Unless you turn the IRQ off while
you're performing some other task, it will, like dat Ole Man
Ribber, jus' keep rollin' along. You have plenty of time
between IRQs to perform a few asks like incrementing
other counters etc

Have you measured the actual crystal frequency ?

32768 seconds is over 9 hours, and a 5 second deviance
is not totally surprising. Unacceptable, but without verifying
that the crystal is true (and temperature compensated if
possible), you can't point the finger at the s/w. What caps
have you got ? Possibly the crystal is not being correctly
driven, but 15,260ppm is way out of spec

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