Please add PDM example - proposal here

[Tuet]

Problem Description

Hi, very nice library, but I took me ages to get PDM on ESP32-S3 to output something usable. Culprit was that .pin_bck MUST be set, otherwise no audio. I got it working now, please add the following example that is derived from examples/examples-stream/streams-generator-i2s/streams-generator-i2s.ino

/streams-generator-i2s-pdm.ino

Device Description

Use a ESP32-S3, select any Pin for PDM where your Amp/Speaker is connected. You MUST choose another pin for clock output even if you not use it - otherwise NO audio output.

Sketch

/**
 * @file streams-generator-i2s-pdm.ino
 * @author Phil Schatzmann
 * @brief see https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-stream/streams-generator-i2s-pdm/README.md 
 * @copyright GPLv3
 */
 
#include "AudioTools.h"

AudioInfo info(44100, 2, 16);
SineWaveGenerator<int16_t> sineWave(32000);                // subclass of SoundGenerator with max amplitude of 32000
GeneratedSoundStream<int16_t> sound(sineWave);             // Stream generated from sine wave
I2SStream out; 
StreamCopy copier(out, sound);                             // copies sound into i2s

// Arduino Setup
void setup(void) {  
  // Open Serial 
  Serial.begin(115200);
  while(!Serial);
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);

  // start I2S
  Serial.println("starting I2S...");
  auto config = out.defaultConfig(TX_MODE);

    // special PDM config starts here...
    config.signal_type = PDM; // Use PDM
    config.pin_data = 6; // Pin on that audio comes out (but Left+Right is merged together!)
    config.pin_bck = 17; // Pin where clock comes out (you MUST select a pin even if nothing is connected to it, otherwise no audio output even from .pin_data!)
    // ...end of PDM config. Rest is standard config.
  
  config.copyFrom(info); 
  out.begin(config);

  // Setup sine wave
  sineWave.begin(info, N_B4);
  Serial.println("started...");
}

// Arduino loop - copy sound to out 
void loop() {
  copier.copy();
}

Other Steps to Reproduce

No response

What is your development environment (incl. core version info)

No response

I have checked existing issues, discussions and online documentation

• I confirm I have checked existing issues, discussions and online documentation

[pschatzmann]

Please submit a pull request