← index #16248Issue #913
Related · high · value 1.620
QUERY · ISSUE

USB (tested with midi) not working on pico 2 (rp2350 in ARM mode only)

openby ghostopened 2024-11-15updated 2024-11-15
bug

Port, board and/or hardware

rp2 port, pico 2 board

MicroPython version

MicroPython v1.24.0 on 2024-10-25; Raspberry Pi Pico2 with RP2350

Reproduction

This is the script I used:

# MicroPython USB MIDI example
#
# This example demonstrates creating a custom MIDI device.
#
# To run this example:
#
# 1. Make sure `usb-device-midi` is installed via: mpremote mip install usb-device-midi
#
# 2. Run the example via: mpremote run midi_example.py
#
# 3. mpremote will exit with an error after the previous step, because when the
#    example runs the existing USB device disconnects and then re-enumerates with
#    the MIDI interface present. At this point, the example is running.
#
# 4. To see output from the example, re-connect: mpremote connect PORTNAME
#
#
# MIT license; Copyright (c) 2023-2024 Angus Gratton
import usb.device
from usb.device.midi import MIDIInterface
import time


class MIDIExample(MIDIInterface):
    # Very simple example event handler functions, showing how to receive note
    # and control change messages sent from the host to the device.
    #
    # If you need to send MIDI data to the host, then it's fine to instantiate
    # MIDIInterface class directly.

    def on_open(self):
        super().on_open()
        print("Device opened by host")

    def on_note_on(self, channel, pitch, vel):
        print(f"RX Note On channel {channel} pitch {pitch} velocity {vel}")

    def on_note_off(self, channel, pitch, vel):
        print(f"RX Note Off channel {channel} pitch {pitch} velocity {vel}")

    def on_control_change(self, channel, controller, value):
        print(f"RX Control channel {channel} controller {controller} value {value}")


m = MIDIExample()
# Remove builtin_driver=True if you don't want the MicroPython serial REPL available.
usb.device.get().init(m, builtin_driver=True)

print("Waiting for USB host to configure the interface...")

while not m.is_open():
    time.sleep_ms(100)

print("Starting MIDI loop...")

# TX constants
CHANNEL = 0
PITCH = 60
CONTROLLER = 64

control_val = 0

while m.is_open():
    time.sleep(1)
    print(f"TX Note On channel {CHANNEL} pitch {PITCH}")
    m.note_on(CHANNEL, PITCH)  # Velocity is an optional third argument
    time.sleep(0.5)
    print(f"TX Note Off channel {CHANNEL} pitch {PITCH}")
    m.note_off(CHANNEL, PITCH)
    time.sleep(1)
    print(f"TX Control channel {CHANNEL} controller {CONTROLLER} value {control_val}")
    m.control_change(CHANNEL, CONTROLLER, control_val)
    control_val += 1
    if control_val == 0x7F:
        control_val = 0
    time.sleep(1)

print("USB host has reset device, example done.")

Expected behaviour

This example code works on a pico 1, here is the output:

MicroPython v1.24.0 on 2024-10-25; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>> import midi_example
Waiting for USB host to configure the interface...
device disconnected

then mpremote disconnects. I can reconnect and it displays the log output from the example.

kernel log display:

 6041.587646] usb 7-1.1: new full-speed USB device number 9 using xhci_hcd
[ 6041.722135] usb 7-1.1: New USB device found, idVendor=2e8a, idProduct=0005, bcdDevice= 1.00
[ 6041.722144] usb 7-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 6041.722149] usb 7-1.1: Product: Board in FS mode
[ 6041.722153] usb 7-1.1: Manufacturer: MicroPython
[ 6041.722156] usb 7-1.1: SerialNumber: e6613008e343372e
[ 6041.787350] cdc_acm 7-1.1:1.0: ttyACM0: USB ACM device
[ 6259.833061] usb 7-1.1: USB disconnect, device number 9
[ 6260.104404] usb 7-1.1: new full-speed USB device number 10 using xhci_hcd
[ 6260.239359] usb 7-1.1: New USB device found, idVendor=2e8a, idProduct=0005, bcdDevice= 1.00
[ 6260.239362] usb 7-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 6260.239364] usb 7-1.1: Product: Board in FS mode
[ 6260.239365] usb 7-1.1: Manufacturer: MicroPython
[ 6260.239366] usb 7-1.1: SerialNumber: e6613008e343372e
[ 6260.285551] cdc_acm 7-1.1:1.0: ttyACM0: USB ACM device
[ 6260.334768] mc: Linux media interface: v0.10
[ 6260.411764] usbcore: registered new interface driver snd-usb-audio

Observed behaviour

This is the output on the rp2 REPL:

>>> import midi_example
Waiting for USB host to configure the interface...

and it hangs, control characters have no effect.

Meanwhile here is the kernel log:

[ 5138.193121] usb 7-1.1: new full-speed USB device number 4 using xhci_hcd
[ 5138.327835] usb 7-1.1: New USB device found, idVendor=2e8a, idProduct=0005, bcdDevice= 1.00
[ 5138.327845] usb 7-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 5138.327850] usb 7-1.1: Product: Board in FS mode
[ 5138.327855] usb 7-1.1: Manufacturer: MicroPython
[ 5138.327858] usb 7-1.1: SerialNumber: 1c59c033388f3e4e
[ 5138.437887] cdc_acm 7-1.1:1.0: ttyACM0: USB ACM device
[ 5138.437924] usbcore: registered new interface driver cdc_acm
[ 5138.437927] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

Nothing else is printed.

Additional Information

This is probably a core issue with customizable USB on this new port.

Thank you very much for your work on micropython and also for providing this template.

Code of Conduct

Yes, I agree

CANDIDATE · ISSUE

USB device removal appears to cause problems in Windows.

openby ayjaymopened 2024-08-25updated 2025-03-07

Using the midi example code run from mpremote as per the instructions
Verify that the example logs transmit events over MIDI
Connect the Cockos Reaper DAW (most recent version, 7.20) [this can be downloaded for free]
Observe that the Board USB device appears in Reaper's MIDI device list
Create a track, assigning the board USB device as the input
Verify that MIDI events are correctly received
Exit Reaper
Unplug the Pico from the USB port
Plug the Pico back into the USB port
Attempt to connect via mpremote. The COM port previously used is now marked 'in use'
Attempt to restart the computer. It will hang during restart and require power to be cycled
The current USB implementation appears to leave the device in an undetermined state. Reaper is a very mature and stable product and is highly unlikely to be the cause here. Presumably some event which ought to occur when a USB device is disconnected does not occur for the Pico, leaving resources locked and causing shutdown and port acquisition to both fail.
I do appreciate that when the Pico was unplugged the midi example code was still running but for any practical implementation this will be the case as users are accustomed to unplugging USB devices at any time.

1 comment
doodlebro · 2025-03-06

I can't seem to get the MIDI example running after the USB device swaps (from a Mac). My Pico needs a hard reset to show up again, the serial device doesn't come back to be connected to.

Looks like for me, the issue is RP2350 related. On a 2040 board the example works as described!

Related: https://github.com/micropython/micropython/issues/16248

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