Author Topic: Someone with a PIC and C compiler... run an envelope follower program for me?  (Read 7404 times)


I've been thinking about this idea too.  I'd like to build a synth module that provide an Envelope follower, Gate and Trigger Signals and a Pitch-to-CV output.  I think it would probably need 2 PIC's, one for the follower, trigger and gate and a second for the Pitch-to-CV. 

You could take a look at Tom Scarffs Pitch-to-Midi converter for ideas on how to do the input section.  He has implemented it on PIC and his code detects peaks in the signal which is sort of similar to what you want to do.
Looking at the Korg MS-20 pitch-to-CV, they have HPF and LPF before feeding the Pitch detector which would probably help the performance of this design.

For the output you can check out Tom Whiltshires LFO and Envelope projects.  He has implemented envelopes and lfo's using a PIC and uses a Low pass filtered PWM output to get a smooth 0v-5v.

Sounds like quite an undertaking but a worthwhile one.  My hope with this envelope follower would be to completely eliminate the need for a rectifier (ripple) or any filtering (drum machines) - the way I PICture (ha, ha) it in my head since it samples every 20hz it will pick up the loudest part of the signal perfectly.  I actually did a circuit analysis of the MS-20 for a private reading last semester.  The pitch to CV circuit was pretty hot, but ideally I would not need any filtering for this software.  Thanks for those links, I always have a lot of trouble finding synth-pic/avr projects.

Sort of OT but if either of you are willing, what do you think of this as a programmer?

I was planning on getting a pic programmer and an AVR programmer anywyas, it would be convenient to have them both in one device.  Lack of ISD is not a big deal to me, when I had it I hardly used it (maybe I should have more...).  USB and mac compatibility (or windows via boot camp) is a must as I own a macbook pro here... could I use this with any compiler or do I have to use this?  Is there a similar product that's a better choice, either cheaper or more mac-friendly?  Mostly I will be wanting to program a wide variety of pic/avr chips.