Brooke Clarke wrote:

> I'm using Timer 2 as an 8 ms tick interrupt clock.  The 16F88 gets it's 
> external clock from a 1.00000000000000 MHz source.  

Is the number of zeroes indicating the precision of the source? What source
is that?

> But after running for 20 hours the clock is 4 to 5 seconds fast.  Any
> ideas why?  

That's some 55 ppm. For me the question is "fast against what?" How do you
determine that it's fast? It of course requires that both of your sources
are somewhat more precise than 55 ppm.


> In a prior clock using Timer 1 it was a hassle to load the registers and
> keep track of the latency, but it did work.

You can subtract from the current timer value. That handles the latency
automatically.

Gerhard

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