[sdiy] super cheap synthisizers

Ingo Debus debus at cityweb.de
Tue Jun 11 15:53:01 CEST 2002



Paul Maddox wrote:
> If you have TWO internal counters (just adding two 16bit numbers) you only
> need ONE timer..
> 
> I mean;-
> 
> Have a timer so it goes at say 1Mhz, yes?
> Now have TWO speed values
> Freq_a and Freq_b
> use TWO accumulators
> acc_a and Acc_b
> 
> each time the timer fires (1Mhz) you do this
> 
> acc_a = acc_a + freq_a
> and
> acc_b = acc_b + freq_b
> 
> bingo two oscillators ONE timer...

Ugh. Are AVRs really that fast?
Can it still process incoming MIDI now and then?

Using a 12 Mhz 8051 clone (shortest instruction execution time 1
microsecond) right now I'm not even dreaming of that speed. But then
it's fast enough for my purpose.

Ingo





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