USB Audio Class Example

nRF5 SDK v15.2.0
This information applies to the nRF52840 SoC only.

This example uses the USB audio class module . See the documentation of this module for links to relevant specification documents.

This example shows how to declare and register two audio class instances to the USB library:

  • Headphones audio class (2 channel, Fs=48Khz, 16bit PCM format)
  • Microphone audio class (2 channel, Fs=48Khz, 16bit PCM format)

Both classes will enumerate as separate devices. Input audio stream (headphones) is passed to the output audio stream (microphone).

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Input and output audio streams

Setup

You can find the source code and the project file of the example in the following folder: <InstallFolder>\examples\peripheral\usbd_audio

LED assignments:

  • LED 1 shows the USB bus state:
    • ON: State RESUME
    • OFF: State SUSPEND
  • LED 2 shows the USB device library status:
    • ON: USB library STARTED
    • OFF: USB library STOPPED
  • LED 3 shows that a USB audio stream frame has been received:
    • TOGGLE - New frame received
  • LED 4 shows that a USB audio stream frame has been transmitted:
    • TOGGLE - New frame transmitted

Testing

Test the USB Audio Class Example application by performing the following steps:

  1. Compile and program the application.
  2. Connect the development kit to the host computer.
  3. Choose "nRF52 USB Audio Demo" headphones as a default audio output device.
  4. Choose "nRF52 USB Audio Demo" microphone as a default audio input device.
  5. Start audio streaming, for example by playing an audio file on your PC.
  6. Start audio recording.
  7. Verify the recorded audio stream.