AudioConnection patchCord with delay breaks program

[M620sound]

AudioConnection with delay breaks program

Hello,

I developed a program on a Teensy 3.2 and am now trying to get it going on a Teensy 3.6. It's a simple delay line (actually two delay lines in series for a longer total delay). However, it doesn't work on the Teensy 3.6.

The program seems to break (no audio output) as soon as I introduce any AudioConnection involving a delay. If I comment those AudioConnection lines out, the program works.

I've checked these parts individually and they seem fine:
- Mic throughput to the speaker works, which suggests that all my hardware and connections are in good shape.
- Delays work in the Examples > Audio > Effects > Delay demo program for Teensy 3.6, but it uses a synth instead of AudioInputI2S.
- AudioConnection messages work fine as long as a delay isn't involved.

The code is below with annotations. Is this a problem of portability to Teensy 3.6? Is there a different way to achieve this (mic into a delay line)?

Thanks!

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioInputI2S            i2s1;           //xy=60,25
AudioEffectDelay         delay1;         //xy=238,284
AudioMixer4              mixer1;         //xy=248,38
AudioEffectDelay         delay2;         //xy=382,282
AudioOutputI2S           i2s2;           //xy=531,242
//AudioConnection          patchCord1(i2s1, 0, i2s2, 0);   // mic throughput just for testing
AudioConnection          patchCord1(i2s1, 0, mixer1, 0);   // use this instead of throughput when delays are fixed
AudioConnection          patchCord2(delay1, 0, delay2, 0); // any of these will break it
AudioConnection          patchCord3(mixer1, delay1);       // any of these will break it
AudioConnection          patchCord4(delay2, 0, mixer1, 1); // any of these will break it
AudioConnection          patchCord5(delay2, 0, i2s2, 0);   // any of these will break it
AudioControlSGTL5000     sgtl5000_1;     //xy=114,152
// GUItool: end automatically generated code

void setup() {
  Serial.begin(9600);
  pinMode(0, INPUT_PULLUP);
  AudioMemory(120); // Was 160 in the working version on Teensy 3.2
  sgtl5000_1.enable();
  sgtl5000_1.volume(1.);
  sgtl5000_1.inputSelect(AUDIO_INPUT_MIC);
  sgtl5000_1.micGain(63);
  mixer1.gain(0, 1.);
  mixer1.gain(1, 1.);
  delay1.delay(0, 110); // Was 425 in the working version on Teensy 3.2
  delay2.delay(0, 110); // Was 425 in the working version on Teensy 3.2
  delay(1000);
  sgtl5000_1.audioPreProcessorEnable();
}

void loop() {
}

 

[M620sound]

Well, I seem to have my code working now on Teensy 3.6. It appears that using the serial port:

Serial.begin(9600);

in conjunction with connecting a delay, e.g.:

AudioConnection patchCord5(delay2, 0, i2s2, 0);

caused audio to break. Serial port may have been working; I wasn't monitoring that. I still don't see why these two are incompatible, but I don't need the serial port for this project.