This thing was a bit of an experiment with how to make the smallest, cheapest possible (1U) eurorack quantizer.
I have a very simply voltage protected input going to one of the ADC channels. This is quantized into a certain scale, which is selected by touching the exposed screw, which will change the on-board RGB LED to a certain color. I had major, minor and pentatonic I think.
Then it maps the input, which goes from 0-3.3 volts, to onboard 10-bit DAC, which also goes from 0-3.3 volts. At 1v/octave, this gives a decent range for generating melodies in a certain key.
The diodes I'm using to stop input voltages from frying this thing also definitely mess with the linearity of the ADC. So you probably get a 1:1 input-output voltage range from about 0-2.5v, but after that it starts to drift. This would probably be fixable with a few cheap passive components and a bit more know-how.