Possible bug in evkmimxrt1060/usb_examples/usb_device_composite_hid_audio_unified SDK example

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Possible bug in evkmimxrt1060/usb_examples/usb_device_composite_hid_audio_unified SDK example

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EdSutter
Senior Contributor II

Hi,

I'm working with a modified version of the evkmimxrt1060/usb_examples/usb_device_composite_hid_audio_unified project and I believe there's a bug (or at least an improvement that can be made) in bm/audio_unified.c...

The application is pre-configured to run at 48kHz; but I had need to test something at 16kHz; hence, I stumbled on an issue on the USB side of things.  There are two definitions in usb_device_descriptor.h:

#define AUDIO_IN_SAMPLING_RATE_KHZ (48) and #define AUDIO_OUT_SAMPLING_RATE_KHZ (48).

I changed these (plus a few other hardware specific clock adjustments) to 16 and found that the host still thought the USB device was using a 48kHz sample rate.  I then discovered these lines in audio_unified.c:

...

g_deviceComposite->audioUnified.curSampleFrequency = 48000U;

...
g_deviceComposite->audioUnified.freqControlRange.wMIN = 48000U;
g_deviceComposite->audioUnified.freqControlRange.wMAX = 48000U;

...

 

When I changed 48000U to (AUDIO_IN_SAMPLING_RATE_KHZ *1000) my host then saw the device as a 16kHz samplerate.  

NXP Team: please let me know if you agree with this change.  I don't know the USB stack that well, so this is based on empirical observation only.

By the way, the same issue exists for bm and lite/bm.

Thanks,

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Alexis_A
NXP TechSupport
NXP TechSupport

Hello @EdSutter,

I agree with you, you also need to modify this so the host can identify the device sample frequency. I will forward your comments to the applications team.

Best Regards,

Alexis Andalon

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Alexis_A
NXP TechSupport
NXP TechSupport

Hello @EdSutter,

I agree with you, you also need to modify this so the host can identify the device sample frequency. I will forward your comments to the applications team.

Best Regards,

Alexis Andalon

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EdSutter
Senior Contributor II

Great, thanks!

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