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Thread: Teensy 3.6 + SPW2430

  1. #1
    Junior Member
    Join Date
    May 2017
    Posts
    1

    Teensy 3.6 + SPW2430

    Hi all,

    I have successfully used the audio shield to get audio from 2 SPW2430 (https://www.adafruit.com/product/2716) MEMS microphones to play through the headphone output. Thank you to Chip Audette's Teensy hearing aid project for that!

    I want to connect 2 additional SPW2430s using the ADC on the Teensy. I have the DC output of the SPW2430 connected directly to the Teensy ADC pin, as is suggested on the adafruit page. However, I am just getting full scale white noise out of the headphones. Here's the code:

    Code:
    #include <Audio.h>
    #include <Wire.h>
    #include <SPI.h>
    #include <SD.h>
    #include <SerialFlash.h>
    
    AudioControlSGTL5000     sgtl5000_1;    //controller for the Teensy Audio Board
    AudioInputI2S            i2s1;          //Stereo.  Digital audio from the Teensy Audio Board ADC
    AudioInputAnalogStereo   adc12(A14, A15);
    AudioOutputI2S           i2s2;          //Stereo.  Digital audio to the Teensy Audio Board DAC
    AudioMixer4              mixer;
    AudioConnection          patchCord1(i2s1, 0, mixer, 0);  //connect the Left input to the Left gain processor
    AudioConnection          patchCord2(i2s1, 1, mixer, 1);  //connect the Right input to the Left gain processor
    AudioConnection          patchCord3(adc12, 0, mixer, 2);  //connect the Right input to the Left gain processor
    AudioConnection          patchCord4(adc12, 1, mixer, 3);  //connect the Right input to the Left gain processor
    AudioConnection          patchCord10(mixer, 0, i2s2, 0); //connect the Left gain processor to the Left output
    AudioConnection          patchCord11(mixer, 0, i2s2, 1); //connect the Right gain processor to the Right output
    
    const int myInput = AUDIO_INPUT_LINEIN;
    
    void setup()
    {
        Serial.begin(115200);
        delay(500);
    
        AudioMemory(70);
    
        sgtl5000_1.enable();
        sgtl5000_1.inputSelect(myInput);
        sgtl5000_1.volume(0.8);
        sgtl5000_1.lineInLevel(10, 10);
        sgtl5000_1.adcHighPassFilterDisable();  //reduce noise.  https://forum.pjrc.com/threads/27215-24-bit-audio-boards?p=78831&viewfull=1#post78831
    
        //setup gains
        mixer.gain(0, 0.0f);
        mixer.gain(1, 0.0f);
        mixer.gain(2, 1.0f);
        mixer.gain(3, 1.0f);
    }
    
    
    void loop()
    {
    }
    Am I doing something stupid here? Thank you for any suggestions.

  2. #2
    Junior Member
    Join Date
    Apr 2018
    Posts
    11
    Hi,
    Did you use any pre amplification stage when you connected SPW2430 to line in pins?

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