Simple 440Hz tone generator works perfectly with the PT8211 Audio board and Teensy 3.2 developed using the PJRC Audio Design Tool, Arduino IDE 1.8.1 and Teensy Loader 1.41 under Windows 10.

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

// GUItool: begin automatically generated code
AudioSynthWaveformSine sine1; //xy=329,317
AudioOutputPT8211 out1; //xy=523,317
AudioConnection patchCord1(sine1, 0, out1, 0);
AudioConnection patchCord2(sine1, 0, out1, 1);
// GUItool: end automatically generated code

void setup() {
AudioMemory(20);
sine1.amplitude(0.40);
sine1.frequency(440);
}

void loop() {
}


As a control, a similar simple program for the SGTL5000 audio board and Teensy 3.2 also works perfectly with the same Arduino IDE 1.8.1 and Teensy Loader 1.41.

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

// GUItool: begin automatically generated code
AudioSynthWaveformSine sine1; //xy=329,317
AudioOutputI2S out1; //xy=523,317
AudioConnection patchCord1(sine1, 0, out1, 0);
AudioConnection patchCord2(sine1, 0, out1, 1);
AudioControlSGTL5000 sgtl5000_1; //xy=418,391
// GUItool: end automatically generated code

void setup() {
AudioMemory(20);
sgtl5000_1.enable();
sgtl5000_1.volume(0.25);
sine1.amplitude(0.40);
sine1.frequency(440);
}

void loop() {
}


I then installed the latest Arduino IDE 1.8.9 and Teensy Loader 1.46 on a new PC and recompiled both programs. The SGTL5000 board and program works fine, producing the 440Hz tone. However, the PT8211 board and program produces no sound. All you hear is "air". Recompiling back on the 1.8.1/1.41 environment and the PT8211 works fine again.

Is anyone aware of any changes or bugs specific to the PT8211 in the latest tools releases? Thanks for any insight.