System control using a USB audio/MIDI interface

Newer linux kernels offer a USB gadget feature (through the libcomposite module) over USB OTG connections. This allows the configuration of SBCs as audio/MIDI interfaces.

However, preliminary tests only worked for 4 audio channels (on RPi), where we would need at least 16. Furthermore, on the i.MX8 platforms the USB audio gadget didn't work at all.

These limitations should be explored and overcome.

Raspberry Pi

So called USB gadgets (audio, MIDI, ethernet) are possible with the various Raspberry Pi models.

Here are guides for RPi 4 and Rpi 5 ethernet capabilities. Since the OTG USB port is the USB-C port usually used for powering, one must either use a powered USB hub or backpower the board through a 5V pin.