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usb.core.find() fails

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评估

难度
4/5
预计耗时
3-5 天
新手友好度
55/100
Issue 类型
缺陷
描述清晰度
基本清楚
活跃度
活跃
技术栈
c, python
领域
embedded-iot

调研方向

Start with the usb.core.find(find_all=True) call in the reproduction and compare its behavior on the listed working and failing CircuitPython builds for the Feather RP2040 USB Host. The issue also points to examples/usb_host_midi_simpletest_rp2040usbfeather.py as related context. Done means the call returns attached devices on the failing builds, including the SanDisk drive and other USB devices mentioned.

由索引模型根据 Issue 内容生成。

描述

bug usb
CircuitPython version and board name
Adafruit CircuitPython 10.3.0-alpha.3-22-gdb82b25b4d on 2026-07-10; Adafruit Feather RP2040 USB Host with rp2040
Code/REPL
# List all attached USB devices (probably only one).
# For "Adafruit Feather RP2040 with USB Type A Host" device.
# Based (loosely) on examples/usb_host_midi_simpletest_rp2040usbfeather.py

import usb.core
import time


print("Looking for all USB devices...")

while True:
    devices = usb.core.find(find_all=True)
    if devices is None:
        print("No devices")
    else:
        n = 0
        print(f"Iterating on {devices=}....")
        for device in devices:
            n += 1
            print(f"\t#{n}: {device=}")
            try:
                print(f"\t**** Found vendor:product {hex(device.idVendor)}:{hex(device.idProduct)}")
            except Exception as e:
                print(e)
                continue
    print("  Sleeping...")
    time.sleep(1)
Behavior

**** Typical successful output:

soft reboot
code.py output:
Looking for all USB devices...
Iterating on devices=<USBDevices>....
        #1: device=<Device>
        **** Found vendor:product 0x781:0x5581
  Sleeping...
Iterating on devices=<USBDevices>....
        #1: device=<Device>
        **** Found vendor:product 0x781:0x5581
  Sleeping...
Traceback (most recent call last):
  File "code.py", line 9, in <module>
  File "usb_host_lsusb.py", line 27, in <module>
KeyboardInterrupt: 

Code done running.
Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.

Press any key to enter the REPL. Use CTRL-D to reload.

Adafruit CircuitPython 10.3.0-alpha.3-13-gbaa3ca8650 on 2026-07-07; Adafruit Feather RP2040 USB Host with rp2040
>>>

**** Typical failure output:

soft reboot
code.py output:
Looking for all USB devices...
Iterating on devices=<USBDevices>....
  Sleeping...
Iterating on devices=<USBDevices>....
  Sleeping...
Iterating on devices=<USBDevices>....
  Sleeping...
Traceback (most recent call last):
  File "code.py", line 9, in <module>
  File "usb_host_lsusb.py", line 27, in <module>
KeyboardInterrupt: 

Code done running.
Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.

Press any key to enter the REPL. Use CTRL-D to reload.

Adafruit CircuitPython 10.3.0-alpha.3-22-gdb82b25b4d on 2026-07-10; Adafruit Feather RP2040 USB Host with rp2040
>>>
Description

Problem: usb.core.find(find_all=True) returns an empty generator even when something's plugged into the USB A port.

Additional information

This code stopped working with build

CircuitPython 10.3.0-alpha.3-22-gdb82b25b4d on 2026-07-10 (adafruit-circuitpython-adafruit_feather_rp2040_usb_host-en_US-20260710-main-PR11093-db82b25.uf2)

which was supposed to address a previously-reported issue with some MIDI keyboards. Now the issue happens with all USB devices (a SanDisk USB stick was used for testing, as well as other USB devices).

**** Fails on these builds (the one purporting to fix it, as well as the latest build available):

Adafruit CircuitPython 10.3.0-alpha.3-22-gdb82b25b4d on 2026-07-10; Adafruit Feather RP2040 USB Host with rp2040
Adafruit CircuitPython 10.3.0-alpha.3-25-g242fe31782 on 2026-07-13; Adafruit Feather RP2040 USB Host with rp2040

**** Succeeds on these builds (the one before the purported fix, and the latest alpha):

Adafruit CircuitPython 10.3.0-alpha.3 on 2026-06-24; Adafruit Feather RP2040 USB Host with rp2040
Adafruit CircuitPython 10.3.0-alpha.3-13-gbaa3ca8650 on 2026-07-07; Adafruit Feather RP2040 USB Host with rp2040

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