audio 4 channel mic example transmits only 2 channels

clwe commented 2 years ago

Operating System

MacOS

Board

raspberrypi pico rp2040

Firmware

examples/device/audio_4_channel_mic

What happened ?

The device succesfully shows up as a 4 channel USB device, but only 2 of 4 channels transmit the test data.

Channel 1 & 3 transmit a low amplitude saw tooth wave (as expected)
Channel 2 & 4 transmit total silence

How to reproduce ?

compile & flash example to rp2040 open in DAW (tested in Audacity & Ableton Live)

Debug Log as txt file

No response

Screenshots

No response

I have checked existing issues, dicussion and documentation

[X] I confirm I have checked existing issues, dicussion and documentation.

jh2srv commented 1 year ago

Hello, I can confirm this bug occurs also in Windows 10 and the RP2040 (Raspberry pi pico)

PanRe commented 1 year ago

Most likely, this is a problem within the RP2040 device controller driver (DCD), where the handling of the ISO EP may not be correct. This was at least the problem for other MCUs. The UAC driver is most likely not to blame, as it works for many MCUs. I did not investigate the RP2040 DCD however. The DCD is furthmore subject to improvements e.g. see #540. If you have time, please feel free to solve this issue and make PR! Thx in advance :)

hathach / tinyusb