The aim of this project is to make a modular analogue-style (note, it will be mostly based on digital modules) synth. It should be understandable to people getting started in electronics and programming. To this aim, the electronics will be as simple as possible. I will try to make it all work with code in CircuitPython, but it's possible that this won't handle some of the more comeplex parts. It'll be mostly based around Raspberry Pi Pico dev boards as these are easily available and cheap.
I've going to try and keep the relationship between voltage and pitch that traditional modulr synths have. However, instead of 1v per octave, I'm going to try for 0.25V per octave. Over the 0-3.3V range, that should give the same range as a traditional modular synth has in the 0-12V range. It'll also mean that with simple voltage amplifiers / dividers you can make a eurorack module work with this system.
- midi-to-cv. This does more-or-less what you'd expect. It takes midi out from a computer's USB port. Note that at the moment it needs a computer as it doesn't run in USB host mode. This might change in the future (or it could use a Midi DIN port), but for now, it's just computer USB. Todo -- break out different tracks
- Voltage controlled oscillator - square wave that doesn't require anything beyond a Raspberry Pi Pico. Should be able to get it to output some harmonics on different pins
- Fancier voltage controlled oscillator - will be able to create a lot of waveforms (inc. wavetables?), but will require a DAC.
- Passive mixer -- just potentiometers innit?
- Button input - a way of pluggin buttons in and making them boing
- Envelope generator
- voltage controlled amplifier -- not too sure how to do this one. Actually, a voltage controlled voltage divider (i.e. digital potentiometer) would basically do the same job. Add in an amplifier if you want it to go up in volume as well as down.