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Thread: Teensy 3.6 and MEMS mic ICS-43432

  1. #1
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    Teensy 3.6 and MEMS mic ICS-43432

    Hello everyone,

    I am a novice about microcontrollers and the Teensy world.
    I am currently working on a Teensy 3.6 and I am trying to record data from an i2s microphone ICS-43432.

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    I connect my mic directly to Teensy board.

    Unfortunatelly, it seems doesn't work properly!
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    Using a B&K calibrator, I get a strange waveform, the negative part seems "corrupted".
    I do not understand why...

    Can you help me?

    Another question, can I use "Audio System Design Tool" directly with my mic without audio shield?

    Where I can find some example for my "audio recorder"?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
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    Quote Originally Posted by earmello View Post
    Using a B&K calibrator, I get a strange waveform, the negative part seems "corrupted".
    I do not understand why...

    Can you help me?

    Another question, can I use "Audio System Design Tool" directly with my mic without audio shield?

    Where I can find some example for my "audio recorder"?
    I understand that the ICS-43432 is an I2S, that is digital microphone. And distortion is then inside the microphone.
    How did you connect it to teensy?
    Also the ICS43432 is 24 bit and as such not compatible with standard audio-design tool. It would need some mods in the I2S module, in particular limiting the data to 16 bit.
    If you search the forum for 'onehorse mems' you will find some discussion on that mic especially https://forum.pjrc.com/threads/40858...l=1#post128167

  3. #3
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    Uhhh hey wait a second here. The signal source is connected HOW? Has the output from the B&K calibrator been verified to be clean? If it's not clean then how can you honestly state the response is bad. Is the response the result of a bad transducer, speaker or amplifier or both connected to the calibrator. I recommend trying a different type of mic and perhaps scoping the wave shape at the input to the sound transducer before calling the digital mic bad.

  4. #4
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    Quote Originally Posted by grease_lighting View Post
    Uhhh hey wait a second here.
    who you are refering to?
    me or the OP?

  5. #5
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    @WMXZ I'm refering to the op. Thought it would be clear by asking how the signal source was connected to the mic. After all he is the one with the B&K source. Just thinking about garbage in garbage out. If the source is bad then maybe the mic is really doing its job.

  6. #6
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    I am so sorry but MEMS is a digital microphone and it has not distortion!
    B&K calibrator is perfect and it has just been calibrated by a certified laboratory.
    I tested them connecting MEMS to a "miniDSP USB Streamer", and as you can see in the follow pics (waveform, specrtogram and spectrum), the chain works properly. Just a little distortion on 2nd and 3rd armonics.
    Normally I use USB Stremer to connect my 8 mics array to PC and they work very well.

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    Now the problem is understand why I get a so large amount of distortion when I use Teensy board.

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    I connected mic in the following way: Pin11 -> CLK, Pin12 -> WS, Pin13 -> SD.

    and I used this code:

    Es_B_I2S_rev05.ino

  7. #7
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    Hello Earmello,

    Did you resolve your problem?
    Can you share your results?
    Thanks.

    Tim

  8. #8
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    Hi Timoteo,
    I'm working on my Teensy right now, it seems that with the new "Teensyduino ver 1.38" problems are solved.

    This is the proof that problem was software and not in my hardware.

    Anyway, the dynamic is compressed, but the output is "clean".

    In the attached pics you can see the comparison between signal acquired by MiniDSP board (green line) and by Teensy 3.6 (red line).

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