ADHS-Tron - MIDI controlled Korg Monotron
The mission: My friend L's Korg Monotron should become controllable via MIDI from a DAW.
Arduino receives MIDI through input circuit and triggers Gate and Pitch CV inputs on Monotron. As you can hear it's not quite a major or chromatic scale. Arduino Uno's 8bit DAC can't output precise enough voltages for Pitch CV.
The code necessary for above functionality:
At this point it’s about time to tell you that the snippets you see on this page are reconstructed with the help of my git history and I can’t guarantee that the program was completely working/bugfree at that particular commit. If you find something odd please leave a comment and I’m happy to help, correct it, whatever. On the bottom of this page you find a link to the final code that worked for me.
Arduino compatible code needs to be changed slightly to run on a Teensy (different serial ports and obviously pin numbers):
At that time I was not quite sure how I could possibly get the pitches right, I just did not know what the volts/octave definition is for the Monotron. After hours of trial and error I came up with this formula that sounded correctly over almost a 3 octave range (the lowest 3 notes always are a bit too low if you tune your Monotron to about 10:00 o’clock):
Weeks later I found a little mark on the freely available Monotron schematic that probably would have helped a little! ;-)
whole ribbon Vbe offset
Filter controlled via MIDI CC (pink line), playing around with the resonance is always fun
Features presented in order of appearance (If unpatient skip to 2:30 for some acidish sounds)
- Filter cutoff and resonance controlled locally
- Filter cutoff controlled via MIDI CC (pink line), resonance locally
- LFO modulating filter cutoff, amount and rate controlled locally
additional features not shown here
- Filter cutoff controlled via MIDI velocity
- LFO controlled via MIDI CC
Get the final code to this project here: github.com/joj0/adhs-tron. Feel free to fork, send issues and so on!