USB MIDI SysEx messages are garbled

[mzero]

MIDI SysEx messages are sent out the USB MIDI port are garbled.

Example:

import usb_midi

usb_out_port = usb_midi.ports[1]
sys_ex_test_msg = bytes([0xF0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xF0])

usb_out_port.write(sys_ex_test_msg)

The host system should receive an 11 byte MIDI SysEx message.... however it receives:

10:43:23.628    From CircuitPython usb_midi.ports[1]    SysEx       
    F0 01 02 01 01 02 02 01 02 03 01 02 04 01 02 05 01 02 06 01 02 07 01 02 08 01 02 09 01 02 F7

10:43:23.628    From CircuitPython usb_midi.ports[1]    SysEx
    F0 01 02 F7

Code path:

• usb_midi.ports[1].write() in python calls
• usb_midi_portout_write in shared-bindings/usb_midi/PortOut.c, which calls
• common_hal_usb_midi_portout_write in shared-module/usb_midi/PortOut.c, which calls
• tud_midi_write in lib/shared/tinyusb/src/class/midi/midi_device.h, which calls
• tud_midi_n_write in lib/shared/tinyusb/src/class/midi/midi_device.c, which is where the bug is!

The bug in tinyusb was recently fixed and committed: hathach/tinyusb#512

This bug will be fixed when a version of tinyusb is pulled into this project that is past that fix. This bug is here to make sure it doesn't get missed.

[mzero]

Oops, forgot to add: This bug is observable in both release and latest versions of CP. From my test device boot_out.txt files:

• Adafruit CircuitPython 5.3.1 on 2020-07-13; Adafruit CircuitPlayground Express with samd21g18
• Adafruit CircuitPython 6.0.0-beta.0 on 2020-09-21; Adafruit CircuitPlayground Express with samd21g18