The cirrus logic audio card drive is standard in the linux 4.14.52 kernel supplied by Alpine Linux, and the driver loads when the firmware overlay is installed. After this, it is necessary to configure the card as desired using the amixer cset capability. The original versions have been updated for the current driver and can be found at http://www.horus.com/~hias/tmp/cirrus/cirrus-ng-scripts.tgz. They have been rewritten to use a common function definition script file and the new register names.
I use a Sony Stereo ceramic electret condenser mic ECM-CS3 which needs a 5v mic bias. The script Record_from_Linein_Micbias.sh sets the cirrus logic card up fine for this and recording works fine. Playback currently through a pair of earbuds for testing.
The idea is to put the RPi, a battery and the mic in a small satchel bag and put it on the floor in the middle of the acoustic jam sessions to record the tunes. I plan to setup an Open Sound Control interface on a tablet to adjust the mix, more on that to come.
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