USB Host mode and dedicated wiring

[mungewell]

Hi, Very interesting project, but not sure I am understanding the USB operation.

It looks like the M0 does not have the ID wire connected, so does this mean that the f/w is forcing it into USB Host Mode? If so, what is the recovery process for when 'we' want to upgrade the f/w or purpose for something else?

Looking at the pictures here: https://learn.adafruit.com/adafruit-trinket-m0-circuitpython-arduino/overview

It looks like the D+/D- are also available as pads on the underside. Yes! This would make it much simpler to use in my project to host a Midi keyboard for my Uno Synth (2.5mm Midi in).

Just a regular USB Type A->Type Micro B cable cut D+/D- 1/2 way and solder direct to pads, then GND/VDD are shared between all Type-A, M0 and Type-miniB.

Any recommendations for a SMT single gate buffer chip for Midi UART out?

Thinking this (and the resistors) could just be super/crazy glued to underside of PCB with flying lead to Uno.

Cheers, Simon

[gdsports]

If so, what is the recovery process for when 'we' want to upgrade the f/w or purpose for something else?

Double click the reset button puts the samd21 in bootload mode.

[olivierjan]

The pads on the underside are not D+ anD- but only +5v and GND.