Audio 2ch mic example

[kaspernyhus]

Please see: audio_2_channel_mic_freertos

I'm trying to make a 2 channel microphone example building on the 4 channel mic example I ported to freertos to run on the Espressif ESP32-S3. This example outputs 4 triangle waves at different periods and is working (image attatched)

However now when I'm trying to do the same with 2 channels, I don't see any payload data in the USB frames.

I have made new descriptors to accommodate for the change in channel count, but apart from that it should be the same. I'm not using encoding in both 4ch and 2ch examples, and therefor use tud_audio_write to transfer the sample bytes to the USB FIFO. I'm pretty sure the device is enumerated correctly as it shows up and Linux doesn't complain about it. Wireshark reveals that the host is actually requesting the 192 bytes pr frame as expected, but the device returns 0 bytes.

@PanRe do you have an idea about why this could be?

Many thanks in advance!

Kasper Nyhus

[PanRe]

Difficult to say from here. The driver usually sends what is stored in its ep_in_ff FIFO once a transmit command was received. Have a look at this line via a breakpoint and look how many bytes are stored in the FIFO! Let me know what it reports!

[kaspernyhus]

OK, I have had a look at this and I find that the correct number of bytes are present in the buffers. The esp32 has USE_LINEAR_BUFFER_TX set as dcd_edpt_xfer_fifo in the device driver is not supported

For 1 channel there are 96bytes in both ep_in_ff.buffer and lin_buf_in

and for 2 channels there are 192 bytes

all as expected

What does this suggest?

Thanks for your help!

[kaspernyhus]

Turns out switching to another device driver fixes the problems I have.
See here

[PanRe]

Interesting... well i am not aware of all the device drivers out there.

@hathach how should we handle all the device drivers? I guess fixing bugs in dwc2 and the individual device drivers is not worth it. Shouldn't all drivers which are covered by dwc2 put away?

[hathach]

@PanRe yeah, the goal is using dwc2 for all chips. However, since lots of espressif codebase is already using dcd_esp32sx.c and they continue to make pr/fix to that driver. They are probably more conformable with esp specific driver. I guess we will do syncing driver one after a while. And giving user option to choose from since the generic dwc2 is far from perfect now. I will do cherry pick fix to dwc2 later on (current buried in other works)

[tore-espressif]

Hello @hathach , I'd like to shed some more light into our plans with DCD layer.
Although we made some hotfixes to the esp32sx DCD, we would like to move the dwc2 implementation. It is already working in our setups, we just need to do more testing before opening PR in your upstream project. We'll keep you updated!

[hathach]

@tore-espressif awesome thank you for your update, that is great to hear you plan to move to dwc2 as well. The driver has more code and probably a bit more complicated since it support a wider range of synopsys configuration, especially those with highspeed PHY support. When I have more time to work on dwc, I will migrate/upgrade/update hotfix from dcd_esp32sx to dwc2 with more testing as well.

[StuartIanNaylor]

ArmDeveloperEcosystem/microphone-library-for-pico#3 (comment) supposedly 4 mic has been done

[kaspernyhus]

Are you aware of any 2 channel mic implementations?
Thanks a lot

[StuartIanNaylor]

I am presuming you can just hack the above as with UAC audio you get chan1,chan2,chan3,chan4 in sequence with stereo its just chan1,chan2.
Only had a brief look but think they used tinyusb as seen a few for a single mic but thinking the above should give you a gist on how to handle channels.

[kaspernyhus]

Also what I thought. I can do 1 channel and 4 channels successfully but I’m not able do a stereo mic

[delingren]

Have you ever found a 2-channel implementation? I'm trying to do exactly the same thing. I got the device recognized as a stereo mic but the data is messed up. I'm not super well versed in USB protocol. It'd be nice to be able to copy an implementation or use it as a reference.
Thanks.