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cherry-embedded / CherryUSB

CherryUSB is a tiny and portable USB Stack (device & host) for embedded system with USB IP

Home Page:https://cherryusb.readthedocs.io/

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USB HS Device : UAC2 issues

OpusElectronics opened this issue · comments

commented

Hello,

I've been testing CherryUSB on a CH32V307 and it looks great.
Having issues with the audio class though. I've tested the following:

audio_v2_mic_speaker_multichan_template.c

There is no audio example yet on the following repo: https://github.com/CherryUSB/cherryusb_wch , but following other examples, I have set up a project with the above demo template. The USB device is correctly recognized as a UAC2 device with the corresponding bit format and sample rates defined in the audio_v2_mic_speaker_multichan_template.c code. So, that's encouraging. :)

The part that doesn't work properly though is once we start streaming audio from/to the device. On Linux (tested on 2 different machines, same problem), we get a lot of the following kind of error in dmesg:

retire_capture_urb: 18822 callbacks suppressed

My guess is that in the usbd_audio_iso_out_callback() and/or usbd_audio_iso_in_callback(), we are not sending/receiving the appropriate number of bytes.

In the demo code, you call:
usbd_ep_start_read(AUDIO_OUT_EP, read_buffer, AUDIO_OUT_PACKET); in usbd_audio_iso_out_callback().
I've tried changing AUDIO_OUT_PACKET to nbytes, but it doesn't change much.
I've also tried adding the following line in usbd_audio_iso_in_callback()

usbd_ep_start_write(AUDIO_IN_EP, write_buffer, AUDIO_IN_PACKET);

(in your demo code, it's empty), but it doesn't solve the issue either.

There's probably something I've overlooked - could you help with this audio class? That would be great.

commented

Audio does not support on all ch32 chips because with no iso driver( you can ask official for help), thanks.

commented

You can try other chips like hpm or bouffalolab.

commented

Thanks. So audio can't work as isochronous transfers are not currently supported in CherryUSB for the CH32 chips?
Is this planned in the future?

commented

Thanks. So audio can't work as isochronous transfers are not currently supported in CherryUSB for the CH32 chips? Is this planned in the future?

No plan. I do not want to guess iso drivers with official registers without reference.

commented

Thanks, I will.