PDM2PCM processing steps

[frnt]

Hello,

I have used the PDM2PCM library successfully on stm32f4. However, on stm32wl that library is not available and cannot be imported because of the missing FPU.

Can someone help me understanding the processing steps performed by the library? Because I would like to make a custom implementation of the PDM2PCM conversion.

Just after the DMA, where all the uint16 are collected and not yet decimated, what are the steps? Are the pdm firstly decimated by the Decimation factor and then goes to LPF? Or the library do something different?

thanks in advance

[Andrew Neil]

https://community.st.com/s/question/0D53W00000nYKygSAG/pdm2pcm-example-code

UM2372 mentioned there contains flowcharts and algorithm description...

[frnt]

Dear @Andrew Neil​ ,

thanks for your reply! I have found some useful information. However, I cannot find the information about the filters used (kind), number of taps….

I don’t think there is only the low pass FIR with decimation, plus the high pass filter. I suppose there is some additional processing…