[sdiy] New TOG board: $0.02 needed

[Nicholas Gregorich]

Scott Gravenhorst wrote:
> Scott Nordlund <gsn10 at hotmail.com> wrote:
>> I've always wanted to retrofit a TOS-based synth with something 
>> that output Walsh functions instead of simple 2'/4'/8'/16' 
>> squares. Of course this would require all the octave dividers to 
>> be replaced (with CPLDs?) 
> 
> IMO, an FPGA would be more appropriate, lots more logic to play with.  Then you can go completely
> nuts with the design.  Also, a CPLD has no dedicated multipliers, AFAIK, a Walsh synth would need
> multipliers so that each logic output can be amplitude controlled rather than simply on/off.  An
> FPGA has this capability.
> 

If you control amplitude in the FPGA then you need a DAC (rather than 
just an output pin) and a way to control the amplitudes (MIDI or ADC).

I think part of the beauty of a Walsh generator is that you can actually 
put it in a small CPLD and build a mixer, that's it. No development kits 
  needed.

Nicholas