This simple firmware allows you to build a USB MIDI Host to Host adapter, using 2 Seeed XIAO SAMD21 boards.
The same firmware goes on both boards.
The hardware connections are:
- RX -> TX
- TX -> RX
- GND -> GND
The primary use case is to connect your PC to a MIDI device which only has USB MIDI Host input, maybe for testing, or for production or performance.
Any Baud rate will be fine, I have used 31250 for no particular reason.
Since both boards are in USB Device mode, power comes from the connected MIDI devices, so no other power is needed.
Here is the USB-MIDI spec, in case you are curious, the header definitions are on page 11: https://usb.org/sites/default/files/midi10.pdf
