Hi, now it seems I can successfully sample audio data, below is the spectrum of 10KHz tone signal.
However, in an acoustically quiet room, the mic can still sample high freq noise, which confused me.
Now there are 2 things also confuse me:
- It seems the PDM sampling rate changes according to I2S audio freq(audio sampling rate), and PDM sampling rate/PCM sampling rate ratio seems to be a constant value, which is 32. i.e. user can not independently change PDM sampling rate and the decimation factor is fixed which is 32? So the decimation factor 64 in the sample project I don't know...
- In the example the output data format is uint16, however it seems int16 data type is more suitable?
I found that decimation factor should equals to # of PDM bits/# of PCM samples, is that correct?
thx
