This is a simple MIDI to CV synth module in Kosmo format. Of course there is already the LMNC Midimuso module, but I decided it does more than I need. Mainly I’m using MIDI to plug in a keyboard to a monosynth, so I don’t need six MIDI channels and 18 outputs, and devoting 10 cm of my case to a module I’d only use less than a third of the capability of didn’t seem to make much sense.
Hence MCVI (MIDI to CV mark I). It provides pitch and velocity CV, gate, and trigger for Note On events as well as pitch bend and modulation CV for one MIDI channel, and 1- and 4- pulse per quarter note clock outputs.
This project is adapted from https://github.com/elkayem/midi2cv.
It handles a range of 88 MIDI notes, corresponding to a standard piano keyboard, using a 12 bit DAC. CV output is 0 V (for MIDI note 21, A0) to +7.25 V (MIDI note 88, C8). Note selection in case of multple keys pressed is governed by a switch selecting lowest note, highest note, or most recent note priority.
Pitch bend CV range is 0 to +1.0 V (0.5 V when centered). Velocity and modulation CV range is 0 to +4 V. Gate, trigger, and clock outputs are +5 V; trigger and clock pulse width is 20 ms.
The module is built around an Arduino Nano. The sketch uses the standard MIDI and SPI libraries.
While the LMNC module is more than I need, this is just about sufficient for now. But sooner or later I’ll probably want another MIDI channel or three and some more configuration flexibility. So I’m already thinking about MCVII. But I decided to get this quick and easy module done for now, and then I can come up with something better at my leisure.
Schematics, Gerbers, and documentation are here:
I have a few board and panel sets up on Tindie.