[sdiy] TOG Substitute - CPLD

[ziembicki jaroslaw]

----- Original Message -----
From: "The Old Crow" <oldcrow at oldcrows.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, December 14, 2003 4:36 AM
Subject: Re: [sdiy] TOG Substitute - CPLD


>   I made some octave generators from PIC parts, though they were 'simple'
> multiple-concurrent divider-types.  The faster PIC and AVR parts of today
> should be able to do real 'multiple phase-accumulators' TOGs with some
> tight coding.


Dear all,

Two years ago I intended to build a polyphonic synth.

I built a single voice board where a single Atmel AT90S1200
works as a triple digitally controlled oscillator.
The DCOs use the phase accumulator principle (see previous
email from Magnus Danielson). Their outputs are converted into
three sawtooth waveforms in a multichannel 8 bit DAC.

If you use a microcontroller, it makes no sense to build a TOG.
>From a single micro you can get 2 or 3 DCO's which is a typical
count for a single voice. The frequencies can be freely set from 0
to a half of the sampling frequency, typically in steps of
0.001 ... 0.01 Hz !

With a single AVR mega I managed to get 2 DCOs, a 2nd pole
DCF and a DCA, plus 2 LFOs and 2 envelope generators.
All this runs from an 8 MHz clock (and most of ATmega micros
can work at 16 MHz).

Regards,
Jarek