USB Device with Headphone/Microphone and CDC-ACM not working

[eng]

I merged the code from the SDK examples "usbd_audio" and "usbd_cdc_acm" and have ensured that each has their own INTERFACE and ENDPOINTS.
I am able to download to the development kit and the following will work or not work:

1) OKAY: Headphones + Microphone
2) OKAY: CDC ACM
3) FAIL: Headphones + Microphone + CDC ACM

Development Environment: Windows 10, nRF52840 DK, Segger Embedded Studio v4.52, nRF5 Software Development Kit v16.0.0
My code is attached. You can copy it to a subfolder (eg "C:\nRF5_SDK\projects\test.2") within the SDK root folder to build.

Just comment/uncomment the following lines (line 31 to 33) in main.c to try out.
Line31: #define HAS_HP
Line32: #define HAS_MIC
Line33: //#define HAS_CDC

Any help is greatly appreciated.
Thanks

test.2.rar

[Sigurd]

Hi,

I see the same issue as you describe here. When CDC ACM is added, USB audio does not work. Interface/EP numbers seems fine, so a USB sniffer trace is likely needed to debug this further.

If you have a USB sniffer, please upload the sniffer traces here. If not, I will try to get hold of a USB Sniffer, and capture some traces.

[eng]

Sigurd,

Sorry, I do not have a USB Sniffer on my end.

Could you kindly capture on your side?

Thanks a lot!

Eng

[engleok]

Hi,

I just found the solution.

We need to include an "INTERFACE_ASSOCIATION DESCRIPTOR" (IAD) just before the "INTERFACE DESCRIPTOR" for the AudioClass Control Interface.

On Windows, it works WITHOUT the IAD when there are NO CDC-ACM descriptors. However, once CDC-ACM descriptors are added, the AudioClass descriptors will NOT be parsed correctly during USB device enumeration. Adding the IAD solves this problem.

I read on the link below that someone did not have the issues on Mac but then had it on Windows. So perhaps it is a Windows problem. https://devzone.nordicsemi.com/f/nordic-q-a/54905/usb-cdc-acm-with-audio-class-on-windows

thanks

Eng