[sdiy] DsPIC timer issue when used as DCO!

[Dave Manley]

> On 12/09/2009 05:34 PM, karl dalen wrote:
>> Hello!
>> Have anyone found the exact source for the glitch problem in
>> dsPIC timers when used as NCO's as displayed in the P08, Mopho?
>> (Minor error, but anyway.)
>>
>> It has to do with the update of the timers registers as some folks 
>> claims?
>> Timer value buffer update delay becomes progressively worse as frequency
>> goes down. The rollover causes delay? As they say?
>>
>> But if not the case shouldn't this be matter of voice channel update
>> procedure i.e pitch after end of VCA EG so the pitch change not become 
>> audible?

Does the NCO reset its counter after the terminal count is changed?  Say 
the counter is set for a terminal count of N, and then is changed to 
M<N.  If the counter has already passed M when the update occurs, then 
it would have to wrap around to 0.

Sounds pretty obvious and broken, and not something that would get 
released to production, but who knows...

-Dave