RE: nRF52: Analog Audio > SAADC > PDM Module > PCM Mono Audio?

Anders Strand — Tue, 27 Oct 2015 09:05:10 GMT

Hey.

I doubt that moving saadc samples into the PDM->PCM converter of the PDM module can be done. The PCM conversion happens directly from the input pins. See the nRF52 OPS chapter 41.

The type of microphone you are planning to use will most likely also cause you some issues. By personal experience, i know that they usually have very narrow dynamic range. This means that they can tell between "no sound", and "high sound", but cannot pick up everything in between. Some microphone modules come with adjustable gain, this helps somewhat.

So in conclusion, i would advice you to buy a microphone with PDM output. We also have a i2s module on our nRF52. There exists microphones with this interface as well.

-Anders