[sdiy] Top Octave Generator (was Chinese MG-1s??!?)

[Eric Brombaugh]

Tom Wiltshire wrote:

> The best way to replace a TOG with PICs would be to use little 8-pin 
> chips and use twelve of them!
> 
> If that seems like too many chips, pull all the divider chips out as 
> well, and then replace the TOG and the dividers by having twelve chips 
> that each produce a single note at all required octaves.

Don't you think you could get 12 square-wave NCOs into a single dsPIC33F 
running at the full 40MHz clock rate? It might be a little tight, but I 
bet you could do it. You might sacrifice a little frequency resolution 
by running them on only 16-bit phase accumulators to speed things up a 
tad, but it probably wouldn't be any worse than the 9-bit divisors 
mentioned earlier.

>> But if one IS going to do it - please use a RF vco for the clock of the
>> micro, so one can pitchbend the instrument.
> 
> This could also be done with an A/D input and software, but the point 
> still stands.

If all the NCOs are in a single dsPIC you could slew them all around 
with one ADC input...

Eric