Issue recording audio longer than 3 seconds with Audio Adapter board

N

nachoman

Member
Hi, I have just got a Teensy 4.0 using the Teensy Audio Adapter board (https://www.pjrc.com/store/teensy3_audio.html). So I have put together some code, which allows me to record audio directly from a microphone, connected to the Audio Adapter board. Which works! However, it only seems to record 3 seconds before just stopping. There is no interrupt to the stop recording pin and that seems to be handled fine when I send a low signal to the pin. I have attached the source code and the output from the serial monitor for the SD write speed and interrupt serial notification. Interesting to see that the SD write speed becomes extermely fast, presumably around the time the audio stops recording. Any advice on how to increase the duration of the audio recording please? Thanks in advance.
Code: 
#include <Bounce.h>
#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioPlaySdWav           playSdWav1;
AudioInputI2S            i2s2;           //xy=105,63
AudioAnalyzePeak         peak1;          //xy=278,108
AudioRecordQueue         queue1;         //xy=281,63
AudioPlaySdRaw           playRaw1;       //xy=302,157
AudioOutputI2S           i2s1;           //xy=470,120
AudioConnection          patchCord1(i2s2, 0, queue1, 0);
AudioConnection          patchCord2(i2s2, 0, peak1, 0);
AudioConnection          patchCord3(playRaw1, 0, i2s1, 0);
AudioConnection          patchCord4(playRaw1, 0, i2s1, 1);
AudioControlSGTL5000     sgtl5000_1;     //xy=265,212
// GUItool: end automatically generated code

Bounce buttonRecord = Bounce(0, 8);
Bounce buttonStop =   Bounce(1, 8);  // 8 = 8 ms debounce time
Bounce buttonPlay =   Bounce(2, 8);

const int myInput = AUDIO_INPUT_MIC;

#define SDCARD_CS_PIN    10
#define SDCARD_MOSI_PIN  7
#define SDCARD_SCK_PIN   14

int mode = 0;  // 0=stopped, 1=recording, 2=playing

char filename[15];
File frec;

void setup() {
  pinMode(0, INPUT_PULLUP);
  pinMode(1, INPUT_PULLUP);
  pinMode(2, INPUT_PULLUP);

  // uses this memory to buffer incoming audio.
  AudioMemory(60);

  sgtl5000_1.enable();
  sgtl5000_1.inputSelect(myInput);
  sgtl5000_1.volume(0.5);
  sgtl5000_1.micGain(60);

  SPI.setMOSI(SDCARD_MOSI_PIN);
  SPI.setSCK(SDCARD_SCK_PIN);
  if (!(SD.begin(SDCARD_CS_PIN))) {
    // stop here if no SD card, but print a message
    while (1) {
      Serial.println("Unable to access the SD card");
      delay(500);
    }
  }
}

void loop() {
  // First, read the buttons
  buttonRecord.update();
  buttonStop.update();
  buttonPlay.update();

  // Respond to button presses
  if (buttonRecord.fallingEdge()) {
    Serial.println("Record Button Press");
    if (mode == 2) stopPlaying();
    if (mode == 0) startRecording();
  }
  if (buttonStop.fallingEdge()) {
    Serial.println("Stop Button Press");
    if (mode == 1) stopRecording();
    if (mode == 2) stopPlaying();
  }
  if (buttonPlay.fallingEdge()) {
    Serial.println("Play Button Press");
    if (mode == 1) stopRecording();
    if (mode == 0) startPlaying();
  }

  // If we're playing or recording, carry on...
  if (mode == 1) {
    continueRecording();
  }
  if (mode == 2) {
    continuePlaying();
  }

  // when using a microphone, continuously adjust gain
  if (myInput == AUDIO_INPUT_MIC) adjustMicLevel();
}


void startRecording() {
  Serial.println("startRecording");
  for (uint8_t i=0; i<9999; i++) {
    // Format the counter as a five-digit number with leading zeroes, followed by file extension
    snprintf(filename, 11, " %05d.RAW", i);
    // Create if does not exist, do not open existing, write, sync after write
    if (!SD.exists(filename)) {
      break;
    }
  }
  frec = SD.open(filename, FILE_WRITE);
  if (frec) {
    queue1.begin();
    mode = 1;
  }
}

void continueRecording() {
  if (queue1.available() >= 2) {
    byte buffer[512];
    memcpy(buffer, queue1.readBuffer(), 256);
    queue1.freeBuffer();
    memcpy(buffer+256, queue1.readBuffer(), 256);
    queue1.freeBuffer();
    elapsedMicros usec = 0;
    frec.write(buffer, 512);
    Serial.print("SD write, us=");
    Serial.println(usec);
  }
}

void stopRecording() {
  Serial.println("stopRecording");
  queue1.end();
  if (mode == 1) {
    while (queue1.available() > 0) {
      frec.write((byte*)queue1.readBuffer(), 256);
      queue1.freeBuffer();
    }
    frec.close();
  }
  mode = 0;
}


void startPlaying() {
  Serial.println("startPlaying");
  playRaw1.play("RECORD.RAW");
  mode = 2;
}

void continuePlaying() {
  if (!playRaw1.isPlaying()) {
    playRaw1.stop();
    mode = 0;
  }
}

void stopPlaying() {
  Serial.println("stopPlaying");
  if (mode == 2) playRaw1.stop();
  mode = 0;
}

void adjustMicLevel() {
  // TODO: read the peak1 object and adjust sgtl5000_1.micGain()
  // if anyone gets this working, please submit a github pull request :-)
}

Output:
Record Button Press
startRecording
SD write, us=196
SD write, us=195
SD write, us=195
SD write, us=195
SD write, us=195

Continues writing "SD write, us=195" for a while.... Then presents:
SD write, us=0
SD write, us=1
SD write, us=0
SD write, us=0
SD write, us=1
SD write, us=0
SD write, us=0
SD write, us=1
SD write, us=0
SD write, us=0
SD write, us=1
SD write, us=0
Stop Button Press
stopRecording
 
I don't think this is an audio issue. It seems like the SD card is failing rather than writing extremely fast. You would need to check the error logging from the SD library to see why. It might be because you need to flush() the file, or perhaps periodically save and reclose it?
 
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