Great job! #1
Description
Dear @rppicomidi,
I've had some time to experiment with your fork of tinyusb and tried to refactor the code on this one to work as a transparent passthrough (zero filter) of MIDI commands between the pc software and a guitar pedal and to make it work on the Arduino environment. I'm using the pico to intercept the communication between PC and pedal so that I can inspect the MIDI messages through another pico connected via uart.
I was having some issues with the device connected to the PIO-usb port not communicating but while writing this issue asking for help I've made some changes and now the code is working as it should (untill I break it again).
At first I was getting an error if I called tuh_descriptor_get_device inside the tuh_midi_mount_cb and tuh_midi_configured always returned 0. After commenting this line things started to get going.
I've have merged your forked tinyusb and Adafruit_TinyUSB_ArduinoUSB library so that I could use it as a library on the Arduino IDE. Things seem to work ok as both device and host are initialized: the PC sees the pico as a MIDI device when the pico copies the pedal descriptors.
I'm still struggling with USB communications, as I'm new to it... I'm still low on USB vocabulary.
Anyway, I wanted to give you some sort of feedback about your repos as you did a fantastic job!