I2S PDM tx mode is not working on ESP32 (works on at least ESp32S3 instead)

[paolo960]

Problem Description

For ESP32 regular, PDM tx mode is not included in /src/AudioToolsConfig.h. Only PDMrx is supported.
Solved adding on row 282

FROM

// ----- Regular ESP32 -----
#if defined(ESP32) && !defined(ESP32X) && !defined(CONFIG_IDF_TARGET_ESP32H2)

if ESP_IDF_VERSION > ESP_IDF_VERSION_VAL(5, 0 , 0)

define USE_INT24_FROM_INT

#endif

TO

// ----- Regular ESP32 -----
#if defined(ESP32) && !defined(ESP32X) && !defined(CONFIG_IDF_TARGET_ESP32H2)

define USE_PDM // added on 5/6/2025

if ESP_IDF_VERSION > ESP_IDF_VERSION_VAL(5, 0 , 0)

define USE_INT24_FROM_INT

#endif

ArduinoMonitorReport.pdf

Device Description

Tested on ESP32devBoard

Sketch

/**
 * @file streams-generator-i2s.ino
 * @author Phil Schatzmann
 * @brief see https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-stream/streams-generator-i2s/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);
  delay(5000);
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Error);

  // start I2S
  Serial.println("starting I2S...");
  auto config = out.defaultConfig(TX_MODE);
  config.copyFrom(info); 
  config.pin_ws  = -1;   
  config.pin_bck = 7;                                       
  config.pin_data= 8;                                    
  config.signal_type=PDM;
  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)

Arduino 1.8.19, ESP32 package 3.2.0, audio-tools release v1.1.0 stable

I have checked existing issues, discussions and online documentation

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

[pschatzmann]

Can you submit a PR ?

[paolo960]

ok i will try next days