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ADAU1787 and PDM mic

Category: Hardware
Product Number: ADAU1787 Evaluation Board
Software Version: Version 4.7. Build 0, Rev 1831 4/5/2022


I am working on ADAU1787. I am trying to connect PDM mic with ADAU1787.i connected PDM mic as according to following connections. i am using pdm mic module by adafruit. I think it works with 1.8v.

3V3    --------    1.8v    // J7

GND  --------   GND    //J7

SEL   ---------   1.8v

CLK   ---------  CLK0         //J5 

DATA  -------- DATA 0/1    //J5


is there anything wrong. mic is not working with this configuration.

  • Harishsharma,

    I have attached an updated version of your project that I believe corrects a couple issues:

    1)  I notice the project did not have any DMIC_EN set.  The DMIC0 will need to be enabled in order to route it to the SigmaDSP.  Likewise, the DMIC_CLK0_ON also needs to be set.  The ADAU1787 will output the DMIC clock to the PDM microphone, and this bit will ensure the clock is sent.  

    2)  For the Pin control, the DMIC_CLK0 and DMIC0/1 pins were set for PDM output.  The ADAU1787 can also route PDM output for driving external amplifiers or other peripherals.  These PDM outputs are not related to the DMICs.  

    3)  Since the XTAL Mode is being used, but the serial port is receiving BCLK / LRCLK, I enabled the ASRCO so that the SDSP data sent out of the serial port is synchronous with the clocks.  

    DIGITAL MIC_Updated.dspproj

    Lastly, I want to confirm that a 3.3V supply is not being connected to a 1.8V node on J7?  

  • Hello galvinpjp,

    yes,3.3v is connected to 1.8v . according to datasheet of module voltage range is 1.8 - 3v but they have not tested it at 1.8v. but it is working at 1.8v.

    Thank you

  • Hello galvinpjp,

    can I connect two mic on same lines by selecting on SEL pin on module. I already did this on this I am facing issue. 

    Thank you

  • Harishsharma,

    I apologize for confusion, are you asking if you can route the data lines from 2xDMIC to the DMIC01 pin for example, and then set the SEL pin for the two DMICs such that one launches data on rising edge and one on falling edge?  

    If this is the setup, then that should be doable.  Each of the DMIC pins can accommodate a pair of DMICs in this fashion.