To read multi-channel PDM signal

[Mao Zeng]

Posted on December 04, 2017 at 04:21

Hi, I am working on a project that needs to read audio signal from 4 PDM microphones. I checked that STM32F405 chipset has

2 muxed full-duplex I2S. Is that mean I can read 4 channel audio data with this mcu? Is there any documentation or tutorial? Thank you very much! 

https://community.st.com/tags♯/?tags=i2s

‌ 

https://community.st.com/tags♯/?tags=audio

‌#audio #i2s

[kraiskil]

Posted on December 04, 2017 at 15:04

If I understood AN 3998 correctly, the when using SPI/I2S for PDM input it works for one channel only because of how the clocking is generated - using SPI/I2S to read PCM is a hack anyways. So no, 4 PDM channels would not be possible with 2 inputs.

I recommend saving yourself a lot of trouble, if possible, by using I2S mics or a PDM to PCM converter chip. Reading 4 PCM channels is no problem.

[waclawek.jan]

Posted on December 04, 2017 at 15:15

Or, better, use STM32 with DFSDM, such as the higher-end 'L4, 'F7, or the newer 'F412/413/423.

JW

[Mao Zeng]

Posted on December 05, 2017 at 01:55

Hi Kalle, thanks. I found some PDM2PCM chip and would like to try out ADAU7002 and TLV320ADC3101.