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Thread: Using an I2S microphone with Audio library and no audio shield... Wiring help

  1. #1
    Senior Member Davidelvig's Avatar
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    Using an I2S microphone with Audio library and no audio shield... Wiring help

    I'm Using Teensy 3.1, and soon 3.2.
    I've done well with an analog mic and the audio library's adc input... Using the wiring shown in the GUI configuration tool. Very cool.
    Now I have an i2s mic from Tindie/Pesky.
    I'm trying to discover the pin connections
    The tool at http://www.pjrc.com/teensy/gui/?info=AudioInputI2S only shows I2S input using the audio shield.
    Can anyone point me to a wiring diagram to connect an I2S mic (slave I assume) to the teensy, allowing use of Audio library's I2S input?

    Thanks

  2. #2
    Senior Member onehorse's Avatar
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    The Tindie page has instructions on how to hook up the I2S mic to the Teensy and get serial data out. IIRC, pin 12 is WS, pin 11 is BCLK, pin 13 is SDOut, and 3V3 and GND of course. Left/Right for stereo to any GPIO. There are other choices on the Teensy for BCLK, SDOut and WS, but these work easily. The I2S mics output serial data in 24-bits embedded in a 32-bit word. The Audio library is currently only for 16-bit audio data. You cannot use it as far as I know for the output from an I2S microphone. But you can capture the I2S serial data and play it back on Audacity or elsewhere. There are instructions for how to do this on the Tindie site as well.

    Check out this thread for a nice application of these microphones.
    Last edited by onehorse; 10-24-2015 at 07:31 AM.

  3. #3
    Senior Member Davidelvig's Avatar
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    I'm a bit confused...
    My use is:
    - audio capture
    - pitch determination with fft1024 plus some math
    - play out with MIDI
    Can I use the 24-bit mic for that audio capture, and have Teensy use the most significant 16 bits?

    For my use above, would you just steer me to stay with an analog mic, and use ADC?

  4. #4
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    Any luck with this Davidelvig? I have one of the Pesky digital microphones as well and would love to use it with the Audio Library if possible. I don't have any need for 24 bits.

  5. #5
    Senior Member Davidelvig's Avatar
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    I've set it aside for now, using a larger electret. It suits my prototyping for now, but I'd love to take advantage of the MEMS small form factor. So, no news for me regarding the Pesky mic

  6. #6
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    Check out my fork of the audio library:https://github.com/whollender/Audio

    I added a couple objects to work with a 24 bit codec. The code assumes that the teensy is the I2S slave, but it should be a good starting point for you.

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