Connect the QT Py RP2040 via USB to a USB MIDI host or a computer running your favorite DAW (digital audio workstation).
Use the skull's left eye jack for a gate out signal. Use the skull's right eye jack for a 1V/oct output.
When you send a MIDI
NoteOn message, a gate and 1V/oct voltage will be sent out of the audio jacks. A
NoteOff message stops the gate signal.
You can change up the code.py file to utilize different MIDI messages or different CV values depending on your needs and synth gear.
If you're interested in seeing how far you can go with Eurorack/CV controlled synths and CircuitPython, be sure to check out Winterbloom. Winterbloom is an open source synthesizer company with hardware and software designed by Thea Flowers.
She designed two modules that utilize CircuitPython: Big Honking Button and Sol. Both modules allow you to modify the CircuitPython code running onboard for custom firmware. Sol is also very similar to this skull project, since it is a MIDI to CV converter, but with four gate outputs and four CV outputs.