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Thread: Playing audio and reading/writing file from SD at same time, possible?

  1. #1
    Junior Member
    Join Date
    Nov 2015

    Playing audio and reading/writing file from SD at same time, possible?

    Hi all

    I'm working on a project that requires the use of logging and reading of data while playing sounds at same time (from the same SD card). I've been for the last 5 days trying to achieve this witout any luck and as soon as I'm reading or writing the SD card, the playing soundg (wav) turns into noise and sometimes justs hangs.
    I don't know if this issue has been posted already but I could not find any similar issue in the forum.

    Maybe it's just not supose to work at all and I'mt trying to do something stupid.

    What I've seen working is reading from a 2nd SD card (audio board and builtin sd) wich is my future aproach if I can not get this working. But would be nice to try and have it working from the same SD card.

    My setup is a Teensy 3.5 with the built in SD card. I have an wav file that plays perfectly when not using the SD card and also I can successfully log/read data from the SD card when not playing sounds. The sd card is a Sandisk ultra of 32G.
    I've looked also into using SdFat library witout any luck. Does anyone knows if this could be done using audio library and sd library?

    I'm attachig the example code I'm using for testing.

    any help or direction woild be very much apreciated, thanks alot!

      SD card read/write
     This example shows how to read and write data to and from an SD card file  
     The circuit:
     * SD card attached to SPI bus as follows:
     ** MOSI - pin 11, pin 7 on Teensy with audio board
     ** MISO - pin 12
     ** CLK - pin 13, pin 14 on Teensy with audio board
     ** CS - pin 4, pin 10 on Teensy with audio board
     created   Nov 2010
     by David A. Mellis
     modified 9 Apr 2012
     by Tom Igoe
     This example code is in the public domain.
    #include <Audio.h>
    #include <Wire.h>
    #include <SPI.h>
    #include <SD.h>
    // #include <SerialFlash.h>
    // GUItool: begin automatically generated code
    AudioPlaySdWav           playSdWav4;     //xy=531,567
    AudioPlaySdWav           playSdWav1;     //xy=534,277
    AudioPlaySdWav           playSdWav2;     //xy=534,372
    AudioPlaySdWav           playSdWav3;     //xy=534,473
    AudioAmplifier           AMP_L1;         //xy=703,257
    AudioAmplifier           AMP_L2;         //xy=703,350
    AudioAmplifier           AMP_L3;         //xy=703,449
    AudioAmplifier           AMP_L4;         //xy=703,545
    AudioAmplifier           AMP_R1;         //xy=705,297
    AudioAmplifier           AMP_R2;         //xy=705,390
    AudioAmplifier           AMP_R3;         //xy=705,489
    AudioAmplifier           AMP_R4;         //xy=705,585
    AudioMixer4              mixer2;         //xy=914,460
    AudioMixer4              mixer1;         //xy=917,378
    AudioMixer4              mixerL;         //xy=1083,585
    AudioMixer4              mixerR;         //xy=1083,654
    AudioAmplifier           amp1;           //xy=1249,585
    AudioAmplifier           amp2;           //xy=1251,655
    AudioOutputAnalogStereo  dacs1;          //xy=1402,623
    AudioConnection          patchCord1(playSdWav4, 0, AMP_L4, 0);
    AudioConnection          patchCord2(playSdWav4, 1, AMP_R4, 0);
    AudioConnection          patchCord3(playSdWav1, 0, AMP_L1, 0);
    AudioConnection          patchCord4(playSdWav1, 1, AMP_R1, 0);
    AudioConnection          patchCord5(playSdWav2, 0, AMP_L2, 0);
    AudioConnection          patchCord6(playSdWav2, 1, AMP_R2, 0);
    AudioConnection          patchCord7(playSdWav3, 0, AMP_L3, 0);
    AudioConnection          patchCord8(playSdWav3, 1, AMP_R3, 0);
    AudioConnection          patchCord9(AMP_L1, 0, mixer1, 0);
    AudioConnection          patchCord10(AMP_L2, 0, mixer1, 1);
    AudioConnection          patchCord11(AMP_L3, 0, mixer1, 2);
    AudioConnection          patchCord12(AMP_L4, 0, mixer1, 3);
    AudioConnection          patchCord13(AMP_R1, 0, mixer2, 0);
    AudioConnection          patchCord14(AMP_R2, 0, mixer2, 1);
    AudioConnection          patchCord15(AMP_R3, 0, mixer2, 2);
    AudioConnection          patchCord16(AMP_R4, 0, mixer2, 3);
    AudioConnection          patchCord17(mixer2, 0, mixerR, 0);
    AudioConnection          patchCord18(mixer1, 0, mixerL, 0);
    AudioConnection          patchCord19(mixerL, amp1);
    AudioConnection          patchCord20(mixerR, amp2);
    AudioConnection          patchCord21(amp1, 0, dacs1, 0);
    AudioConnection          patchCord22(amp2, 0, dacs1, 1);
    // GUItool: end automatically generated code
    const int chipSelect = BUILTIN_SDCARD;
    // const int chipSelect = 10;  
    // SD card
    File datafile;    // for storing into a file
    void setup()
     // Open serial communications and wait for port to open:
       while (!Serial) {
        ; // wait for serial port to connect.
      Serial.print("Initializing SD card...");
      if (!SD.begin(chipSelect)) {
        Serial.println("initialization failed!");
      Serial.println("initialization done.");
      Serial.println(F("\n..................................\n# Setting up: Audio"));
      AudioMemory(40);                   //Definimos la memoria de trabajo para las conexiones de audio
      // regulate volume of the mix
        amp1.gain (0.7);
        amp2.gain (0.7);
        // Regulate players volume
        AMP_L1.gain (1.0);
        AMP_R1.gain (1.0);
        AMP_L2.gain (0.8);
        AMP_R2.gain (0.8);
        AMP_L3.gain (0.8);
        AMP_R3.gain (0.8);
        AMP_L4.gain (0.8);
        AMP_R4.gain (0.8);
    void playFile() {
      Serial.print ("Max blocks used till now: ");
      Serial.println (AudioMemoryUsageMax());
      unsigned long WAVduration = 0;"soback.wav");
      while (WAVduration == 0) {
        WAVduration = playSdWav1.lengthMillis();
      Serial.print ("Audio duration: ");
      Serial.println (WAVduration);
    void loop()
      dumpFile ("stream2.kll");
      delay (1500);
      Serial.print ("FreeRam: ");
      Serial.println (FreeRam());
    void dumpFile (char *_fileName) {
      // open the file. note that only one file can be open at a time,
      // so you have to close this one before opening another.
      datafile =;
      Serial.print(F("Dumping File "));
      if (datafile) {
        while (datafile.available()) {
          char a =;
        Serial.println (F("####### END DATA."));
    uint32_t FreeRam(){ // for Teensy 3.0
        uint32_t stackTop;
        uint32_t heapTop;
        // current position of the stack.
        stackTop = (uint32_t) &stackTop;
        // current position of heap.
        void* hTop = malloc(1);
        heapTop = (uint32_t) hTop;
        // The difference is the free, available ram.
        return stackTop - heapTop;

  2. #2
    Senior Member
    Join Date
    Apr 2014
    Try this:*
    (Can record to wav, despite of the name, and can play +record)

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