How to use nrf5340 as a USB Microphone device?

[RashmiV]

I want to use nrf5340 as a USB Audio Microphone.

I am taking the help of zephyr/samples/subsys/usb/audio/headphones_microphone sample app, which contains USB Headphone + USB Microphone.

To disable USB Headphone, I am commenting hp_dev related code from main.c and I am modifying the nrf5340dk_nrf5340_cpuapp.overlay as follows:

&usbd {
mic_0 {
label = "MICROPHONE";
compatible = "usb-audio-mic";
feature-mute;
channel-l;
channel-r;
};
};

I have a static 192 byte PCM buffer that I want to continuously send over USB, for which I am using the following code in loop:

struct usb_audio_dev_data *audio_dev_data = mic_dev->data;
struct net_buf *buffer = net_buf_alloc(audio_dev_data->pool, K_NO_WAIT);
memcpy(buffer->data, pcm_buffer, buffer_len);
ret = usb_audio_send(dev, buffer, buffer_len);

But it does not work and the code crashes. 

Please advise.

[RashmiV]

No, that is not the case. I have enabled only the microphone device in my code, I am not enabling the headphone device. My dts also has only the microphone. The dts is as follows:
&usbd {
mic_0 {
label = "MICROPHONE";
compatible = "usb-audio-mic";
feature-mute;
channel-l;
channel-r;
};
};

So on the host side, for output I only see one option: the standard system speaker. Whereas for input I see two options: standard mic input and zephyr mic, from which I select the zephyr mic to send audio from the nrf to the host.

[ovrebekk]

Hi

Did this problem occur once you changed from sending a sine wave to sending I2S data?

Have you done some debugging on the nRF side to verify that the I2S data looks OK when you get it from the I2S driver?

Best regards
Torbjørn

[Jeffrey Haynes]

Are you able to post your code?  This seems like a reasonable approach but so far I haven't been able to get it to work without errors.

[upasna maurya]

Hi RashmiV

Actually I want to work on the  samples/subsys/usb/audio/headphones_microphone project. and need a help from you that which hardware you used for the usb microphone and usb headphone to interface with the nrf5340 dev kit? 

[ovrebekk]

Hi

It's more than 3 years since Rashmi posted in this ticket. If you are having issues I would recommend opening a new ticket, and include a summary of what you have tried and the issues you are facing, and we can have a look at it. 

Best regards
Torbjørn