[sdiy] Controller design

[Gordonjcp]

On Wed, Dec 30, 2015 at 11:11:58AM +0100, Thomas Burdick wrote:
> Thanks, this sounds like a good direction to try. There are 10 buttons on the right hand and two on the left, so a 3x4 matrix sounds like exactly what I'd need.
> The bellows will be an analog signal: I need to know both direction and pressure, in order to get the note, but also control the volume; after a certain threshold pressure, I'll want to both modulate the PWM portion of the VCO, and bend the pitch. I'm thinking of using two LED-photoresistor pairs--one for each direction--to measure the amount that an air-blown valve moves, and use them to watch the bellows.

You can buy cheap air-pressure sensors.  I bet you could use that to measure the pressure inside the bellows and bleed air in through a small hole so it "feels right", then measure the pressure fluctuation above and below "normal".

> Having the processor tune the CVs sounds like a fair amount of programming, considering I have not only the nominal notes, but pitch bend to contend with, but is something to think about. I have a PWM component to the VCO, so getting a square wave to the digital input would be no problem.
> Thanks for mentioning the possibility of using a single DAC to feed multiple S&Hs: I'd like to think that would have occurred to me, but it hadn't so far.
> -Thomas

The VCO reset pulse would be a good place to pick up the tuning signal.

-- 
Gordonjcp MM0YEQ