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Thread: Teensy 3.2 + prop shield = no sound

  1. #1
    Junior Member
    Join Date
    Jul 2019

    Teensy 3.2 + prop shield = no sound


    New to this stuff but I have a Teensy 3.2 & prop shield I'm trying to learn on. I've been going through the tutorials/tests found here:

    I'm stuck on the audio portion. I've tried following the steps and I've modified the code like this...

    "With Teensy 3.2, the Teensy Audio Library can be used to create sounds. Nearly all the audio library examples are designed for the Audio Shield. To adapt them for the Prop Shield, replace "i2s1" with "dac1" in the Design Tool, or AudioOutputI2S with AudioOutputAnalog in the Arduino code. Then delete the SGTL5000 object and any code which uses it."

    So I've tried applying this the the "Part_1_02_Hardware_Test" found in the Audio/tutorial examples. Now I don't have ALL the hardware shown in the YouTube video tutorial, I only have the Teensy/Prop Shield USB connected to my laptop and small 4ohm3W speaker attached to the speaker outputs on the shield.

    When I upload the code, there is a small POP and I can hear a very light hiss when I put the speaker up to my ear, but not the beeping found in the video.

    Am I missing something or could someone point me in the right direction?

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    First guess … There is an enable AMP Pinmode and digitalwrite required IIRC - did you add those as well?

  3. #3
    Senior Member+ manitou's Avatar
    Join Date
    Jan 2013
    you also need to connect T3.2 DAC pin to audioIn on the shield

    here is a sketch to play a sine wave through DAC to prop shield (you need to start up serial monitor for it to work)
    // prop shield need pin 5
    // start monitor to hear sound,  hit key to increase freq
    #include <Audio.h>
    #include <SerialFlash.h>
    // GUItool: begin automatically generated code
    AudioSynthWaveformSine   sine1;          //xy=180,469
    //AudioSynthWaveformSineHires   sine1;
    AudioOutputAnalog        dac1;           //xy=380,468
    AudioConnection          patchCord1(sine1, dac1);
    // GUItool: end automatically generated code
    int freq = 1100;
    void setup() {
      while (!Serial);
      Serial.println("Setting up");
      //dac1.analogReference(EXTERNAL);   // louder, default is 1.2v INTERNAL
      pinMode(5, OUTPUT);
      digitalWrite(5, 1);//Enable Amplifier
      Serial.println("Send Serial Char to increase freq");
    void loop()
      if (Serial.available()) {;
        freq += 100;

  4. #4
    Junior Member
    Join Date
    Jul 2019
    Thank you for the input. Manitou, the connections were my problem! I was going off the attached pic I found on the Propshield page of PJRC:Click image for larger version. 

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    I soldered heads/sockets to the 5 on the end that this pic shows as not being used. Again, I'm a NOOB. I've been able to run your code and a couple others I've tried before. They seem to be working now. Thank you all!

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