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ChRegBrg
Visitor II
September 27, 2023
Question

DFSDM Filter for DC-Bias of MEMS-MIC

  • September 27, 2023
  • 1 reply
  • 1057 views

Hello st-community,

I am currently working with MEMS microphones (more precisely: MP34DT05TR-A). For reading in the data I use the DFSDM, which also works as far as possible, because I noticed when evaluating the data using an FFT that there is a very high peak (see picture) at 0Hz. Presumably this is the DC component of the microphone or? Now I would like to remove this by filtering. Is this possible by a clever configuration of the DFSDM module inCubeMX or do I need another library? Or do I have to do this via hardware? Unfortunately I could find nothing about if the filtering is possible via DFSDM-Configuration or a specific software library.

I hope you can help me.

Greetings,

ChRegBrg

spectrum.PNG

 

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    1 reply

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    ChRegBrgAuthor
    Visitor II
    September 27, 2023

    Hello,

    I am glad that after a short time I can answer my own question (partially). Yes, the DC bias can be filtered with a high-pass filter. If someone is also facing this problem, I recommend the video from Phil's Lab which helped me a lot (Video: The Simplest Digital Filter (STM32 Implementation) - Phil's Lab #92).

    I would still be interested if such a filtering is also possible directly with the DFSDM module. Here only FastSinc and Sinc1-3 filters can be selected.I have not found other possibilities/information.

    Greetings,

    ChRegBrg

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