[sdiy] Fast envelope generation

Gordon JC Pearce gordonjcp at gjcp.net
Tue Dec 18 02:05:21 CET 2012

Hi all,

I had a thought about generating exponential envelopes on "small" 
microcontrollers.  Actually calculating an exponential decay is 
computationally expensive, so how about using a lookup table and then 
using something akin to a phase accumulator to set the decay time?

I'd need to work out exactly how to go from the attack phase to the 
release phase, if you released the key during attack.  However for a 
simple decay/release envelope like on a TB303 it would be fine.

I await the onslaught of "it's been done" and "it doesn't work" ;-)

Gordonjcp MM0YEQ

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