Example audio line


This wiki page demonstrates how to verify that the audio out and audio in lines are working.


  • Add a jumper to J16 to choose between audio in/out and bluetooth audio. See closeup of J16 for position of jumper for audio.
  • Audio speaker or stereo headphones with a 3.5mm plug in order to listen to the audio
  • Audio microphone with 3.5mm plug
  • Locate the audio sockets on the dev-kit.

The pictures below show the full dev-kit board and a close-up of the portion with the audio plugs and the J16 jumper.

dev kit - rev 2

Audio close-up


Audio Out

  • Enter the following commands to adjust the output volume
    amixer set PCM 85%
  • Plug the speaker or headphones into the Stereo Out socket.
  • Enter the following command to play a 440 Hz tone which alternates 5 times between the left and right channels
    speaker-test -c2 -f440 -t sine -l 5
  • You should hear a tone which alternates between the left and right speakers or the left and right sides of the headphones. If you only have a mono speaker, then you will just hear a steady tone.

Audio In

  • Enter the following command to adjust the input volume
    Note: Depending on the kernel one of these commands will work and the other error
    amixer set "PCM Capture Mute" unmute
    amixer cset name="PCM Capture Switch" on
  • Set capture volume to something reasonable
    amixer cset name='PCM Capture Volume' 40
  • When using a microphone.
    • Start recording using this command
      arecord -f dat --vumeter=mono test_mic.wav
    • Say something deep and profound
    • The vumeter option will show if audio is detected. Adjust capture volume if audio is too low or too high.
    • Hit ctrl-C to stop the record.
    • Connect the speaker to the Stereo Out socket.
    • Use the following command to play the recording
      aplay test_mic.wav
    • You should hear your recorded message

Note: As of 2023/09, TI has a bug in the kernel which only allows opening the recording device once. A reboot is required to reset and record again.

2b00000.mcasp: Receive buffer overflow


This wiki page has demonstrated how to verify that the Stereo Out is working and then how to make a recording from the Line In and play it back.

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