Wio terminal I2s mic

I did some testing with the wio terminal’s internal microphone and got very noisy results. So I’d
like to try using an external mic for getting audio data.
I have so an Adafruit SPH0645LM4H i2s breakout board (also have their PDM board if anybody has an idea how to use it with the wio terminal…)
But have some trouble getting it to work.

  1. The I2S example (input serial plotter) in the Arduino IDE seems to be broken.
    I get a bunch of errors, starting with:
    error: ‘GCLK_GENCTRL_SRC_DFLL48M_Val’ was not declared in this scope
    int src = GCLK_GENCTRL_SRC_DFLL48M_Val;

  2. Tried using example code from GitHub - Seeed-Studio/Seeed_Arduino_Audio
    But got only zeros.

The pins I used for the mic are:
3.3V -1
ground - 39
bclk -12
dout - 39
lrcl - 35

I’d be grateful for any help with this or any other suggestion for getting good audio using the WIO terminal.