TC!O_3

MIDI-controlled oscillator based on GRAINS for the AE modular format. (get it? cereal? grains? serial? eh? eh?)

Module is based on an Arduino Nano. Schematics developed based on the figure in (https://wiki.aemodular.com/pmwiki.php/AeManual/GRAINS), with several additions:

• A direct MIDI input (socket 1), connected to the Rx pin of the Nano. Switch 1 determines if this pin is connected to the Nano or disconnected (I added the disconnected state because I was concerned that reprogramming over USB would not work otherwise, not sure if this is necessary).
• A 6 bit R2R DAC connected to digital pins 2-7 of the Nano. I wanted a rough CV output which could be programmed to follow the MIDI note (64 steps for 0-5V roughly corresponds to 1 step/semitone), to enable filter tracking (though other uses are certainly possible). I could not get PWM on additional pins to function well in Mozzi mode, so I chose an R2R instead.

SMD parts are 0805 to facilitate user repairs.