Shawn Ellis <PICLIST@MITVMA.MIT.EDU> wrote:

> things don't really point to the 20 Khz since I already tried an
> independent update pulse coming from a counter in a computer
> sitting on my desk and the results were EXACTLY the same.  I also
> tried three different 20 Mhz crystals in the PIC prduceing the 20
> Khz, with no change... So I can only assume this frequency is
> correct.

Shawn:

Is there a chance that you're not really sending exactly the number
of DAC values that you think you are?  Maybe you're "doubling-up" on
one of your lookup-table values?

You can check this by replacing all the sine values in your lookup
table with alternating full-scale (FF or whatever) and zero-scale
(00) numbers, then look at the resulting output square wave and see
if any double-wide pulses or gaps are generated.

-Andy

Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499