rockpi4-mikroe-506

ASoC driver and device tree overlay for the Mikroe-506 (WM8731 board) on RockPi4. It has been confirmed to work on the 4.4.154-90 kernel.

Notes

If you try and build these drivers against the kernel tree shipped by Radxa, you will get "Exec format" errors. This is caused by the erroneous cross-compilation of the kernel tree on the x86 architecture. The issue is described here, and a workaround is suggested.

Another thing to look out for: the default device tree compiler (dtc) shipped from Radxa is too old to support overlays. We have confirmed that version 1.6.0 works; the latest version is available here.

Build/Install Drivers and Overlay:

make
sudo make install

Usage

Connect the Mikroe-506 to the RockPi 4 like this:

Mikroe-506        RockPi4
----------        -------
SCK         <-->  Pin 12
MISO        <-->  Pin 38
MOSI        <-->  Pin 40
ADCL        <-->  Pin 36
DACL        <-->  Pin 35
SDA         <-->  Pin 3
SCL         <-->  Pin 5
3.3V        <-->  Pin 1
GND         <-->  Pin 6

Then, to enable the overlay, add the following lines to /boot/hw_intf.conf:

intfc:i2c7=on
intfc:dtoverlay=rockpi-mikroe-506

Reboot, and check that the new sndmikroe506 device appears in the list of sound cards:

aplay -l

If that looks good, then configure the sound card parameters for input and output:

alsamixer

Press F6, select sndmikroe506, then press F5 for all controls, and:

• 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)

Escape to exit, now test output:

aplay -D hw:2,0 mySong.wav

and mic input:

arecord -D hw:1,0 -r 48000 -f S16_LE -d 5 -c 2 myRecoring.wav