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RPi Audio Codec

2017-10-12 15:30:26 supercollider

Here's how to set up the proto WM8731 based audio codec module from MikroElektronika and use it with SuperCollider on a Raspberry Pi 3.

Power off the RPi and connect the proto board to the RPi with jump wires like this...

Proto         Raspberry
-----         -----
SCK       ->  RPi 12
MISO      ->  RPi 38
MOSI      ->  RPi 40
ADCL+DACL ->  RPi 35  //both proto pins go to the same RPi pin
SDA       ->  RPi 3
SCL       ->  RPi 5
3.3V      ->  RPi 1
GND       ->  RPi 6

See this pinout diagram for help with the RPi GPIO numbering.

Power on the RPi and open a terminal and type...

sudo nano /boot/config.txt

Find and uncomment the first line and add the second...

#dtparam=audio=on
dtoverlay=audioinjector-wm8731-audio

Press ctrl+o to save and ctrl+x to exit.

sudo reboot

Again open a terminal and type...

alsamixer

First press F5 to show all controls, then...

  • enable item 'Mic' (space)
  • set item 'Mic Boost' to 100 (up arrow key)
  • enable item 'Playback Deemphasis' (m key)
  • disable item 'ADC High Pass Filter' (m key)
  • set item 'Input Mux' to Mic (arrow keys)
  • enable item 'Output Mixer HiFi' (m key)

alsamixer screenshot

Now you should be able to start jackd with for example...

jackd -P75 -dalsa -dhw:0 -r48000 -p256 -n2

and get decent in/out sound with only 5.3ms latency.

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