On Wed, 30 Oct 1996, Shawn Ellis wrote:

> The problem is that the resulting sine wave is really 62.52 Hz (5 us too
> fast).  I have used several different sources for the 20Khz update pulse
> with no change in performance so I don't think that could be the problem.

I can't see offhand how the system described could be causing this error,
especially if you've used an external clock source.  I wonder if you have
a problem caused by the measurement technique?  If you're measuring the
period of a single cycle, you may be seeing the effect of a bit of
hysteresis in the input conditioning.  Well, it's a thought.