Test other digital PDM microphones with the AudioHub Nano evaluation board in stereo mode

[HenningGeb22]

Hi,

I would like to test microphones from another manufacturer with the AudioHub Nano, e.g. TDK InvenSense EV_ICS-41350-FX (https://www.digikey.de/en/products/detail/tdk-invensense/EV-ICS-41350-FX/6140309).

I managed to test one mic at a time and get a good quality with it, but don't get a stereo signal in a two-mic configuration to work, just noise in both channels. The TDK InvenSense uses a SELECT pin to be connected to GND for the left channel, and to be connected to VDD for the right channel. If I use the SELECT pin like that or just don't use it, the outcome is the same.

I noticed that the Infineon mics don't use the SELECT pin, is that correct? Any ideas how to connect the new mics to the hub?

[George_T · Accepted solution]

Hi @HenningGeb22,

The microphones from Infineon have PDM left/right select pins as seen in the IM69D130 datasheet.

As seen in the application circuit in the datasheet the microphone select pins are connected to VDD or to ground to select either as left or right channels.

In the figure LR is the Left/Right select pin. In the AudioHub Nano board, select (LR) pin of left microphone is connected to VDD and that of right microphone is connected to Ground. So please connect the microphones accordingly.

Please let me know if this solves the problem.

Best regards,

George