RAK11720 PDM Microphone Pins

[kasuneranda98 (Kasun Eranda)]

Hi!

I’m trying to interface a PDM microphone similar to ST’s MP34DT05-A with a RAK11720. However, I cannot seem to find a pin mapping that mentions which pinas are connected to PDM Data and PDM Clock pins of the Apollo3 MCU (or if they are used by something else). Appreciate if someone could point me in the right direction.

Thanks in advance!
-Kasun

[beegee (Bernd Giesecke)]

Welcome to the forum @kasuneranda98

From the pin out of the Apollo3 there seems to be multiple pins used for PDMC and PDMD:

(1) GP11 and GP12, connected the SX1262 LoRa transceiver ==> not available

(2) GP12 (PDMC), connected to ADC9 pin

(3) GP14 and GP15, connected to SX1262 LoRa transceiver ==> not available

(4) GP 22 (PDMC), not exposed on stamp module ==> not available

(5) GP 29 (PDMD), not exposed on stamp module ==> not available

(6) GP36 and GP27, connected to GPIO36 and GPIO37

(7) GP45 and GP46, but GP46 is not exposed on stamp module ==> not available

I guess (6) is the only option.

If you are using RUI3, there is no support for PDM as far as I know.

[kasuneranda98 (Kasun Eranda)]

Thank you @beegee for the fast response!

(6) is the way to go it seems. Luckily those pins are not attached to anything specific in my application.

The microphone is a new feature, guess I’ll have to resort to Ambiq’s SDK for this one until RUI3 implements supports PDM mics.