This is a stripped down version of the MIDIbox TIA (PDF). It uses a Raspberry Pi Pico and MicroPython to control the Atari 2600 TIA chip for some old-school sound goodness.
The clock signal to the TIA is provided by a PIO state machine instead of a crystal. Realtime modulation of the state machine frequency allows the TIA to output a continuous pitch instead of the original 32 pitches that were most of the time off-scale.
The next step is to add CVs for waveform, volume, and for pitch with 1V/oct.
(Old version)
