[sdiy] In praise of the ATM STM32F303

[Gordonjcp]

On Fri, Feb 12, 2016 at 11:11:08AM +0000, Tom Wiltshire wrote:
> Interesting theory, Olivier.
> 
> Here's a modified alternative:
> 
> Keep the array of amplitudes, but change the way the bank of oscillators is calculated.
> 
> Do it using the same method as the original string machines. We have 12 oscillators tuned to the top octave. Twelve NCO updates doesn't take long to do. The oscillators drive binary counters, which then provide all the different octaves you need in their various bits.
> In order to provide output waveforms, you shape the square-wave outputs from the counter bits using a one-pole IIR filter. This simulates simple RC filtering and gives you somewhere between a triangle wave and a  "shark's fin", depending on your filter coefficient. It *must* be quicker to calculate a IIR filter than do a PolyBLEP.
> 
> Tom

The way I did it in nekostring was to generate a "bottom" octave and use that to set the phase of one of eight polyphonically-assigned voices.

If I was going to generate a mass of sawtooths *now* I'd probably use Tomisawa's method.

Does it have true polyphonic envelopes or is it (like the Solina) paraphonic?

-- 
Gordonjcp MM0YEQ