I've implemented a PDM microphone driver using the nrfx_pdm.c module directly, NOT the zephyr dmic module. We are in the early stages of development, so we are still supporting the nrf7002-dk development kit in addition to the first custom prototype. The PDM pins on the dev kit are different from the prototype, and I'd like to be able to use the device tree for the PDM configuration of pins to have a different build for each of the boards. We have the build already setup, so it's a matter of properly setting up and using the overlay contents to configure and initialize PDM.
nrfx_pdm_config_t has a way to specify clk_pin and din_pin. If I hard code those to the values and set skip_gpio_cfg and skip_psel_cfg to false I have PDM working and can get audio data. But I need that to be different pins for the different boards. So my questions are:
1) What should I change in the overlay configuration below? and
2) How do I initialize the module in code, or alternatively, access the pin numbers to be able to pass to nrfx_pdm_config_t and do the initialization there?
Based on examples, my overlay is shown below, and I can get a pointer to the device using DEVICE_DT_GET(DT_NODELABEL(mic_dev));
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&pinctrl {
pdm0_default_alt: pdm0_default_alt {
group1 {
psels = <NRF_PSEL(PDM_CLK, 0, 25)>,
<NRF_PSEL(PDM_DIN, 0, 26)>;
};
};
};
// Additional settings for the PDM device
mic_dev: &pdm0 {
status = "okay";
pinctrl-0 = <&pdm0_default_alt>;
pinctrl-names = "default";
clock-source = "ACLK";
};
Thanks,
KE
