Audio Amplifier (MAX98357A)

/*
 * ESP32-S3 MP3 Loop Player
 * 
 * USAGE:
 * 1. Place a file named "0001.mp3" in the root of your SD card
 * 2. Connect SD card module
 *    - CS   -> GPIO 15
 *    - MOSI -> GPIO 11
 *    - MISO -> GPIO 12
 *    - SCK  -> GPIO 13
 * 3. Connect MAX98357A I2S amplifier:
 *    - BCLK -> GPIO 14
 *    - LRC  -> GPIO 41
 *    - DIN  -> GPIO 1
 * 4. Upload code and the file will play on loop
 * 5. Adjust volume by changing the number in audio.setVolume(16)
 *    (Range: 0-21, where 21 is loudest)
 */

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

// SD Card pins
#define SD_CS 15
#define SD_MOSI 11
#define SD_MISO 12
#define SD_SCK 13

// I2S pins for MAX98357A
#define I2S_DOUT 1
#define I2S_BCLK 14
#define I2S_LRC 41

Audio audio;

void audio_eof_mp3(const char* info) {
  Serial.println("Track finished - restarting");
  audio.connecttoFS(SD, "/0001.mp3");
}

void setup() {
  Serial.begin(115200);
  delay(1000);

  // Initialize SD card
  pinMode(SD_CS, OUTPUT);
  digitalWrite(SD_CS, HIGH);
  SPI.begin(SD_SCK, SD_MISO, SD_MOSI, SD_CS);

  if (!SD.begin(SD_CS)) {
    Serial.println("SD card failed!");
    while (1) delay(1000);
  }
  Serial.println("SD card OK");

  // Initialize audio
  audio.setPinout(I2S_BCLK, I2S_LRC, I2S_DOUT);
  audio.setVolume(16);

  // Play file
  if (audio.connecttoFS(SD, "/0001.mp3")) {
    Serial.println("Playing 0001.mp3");
  } else {
    Serial.println("File not found!");
  }
}

void loop() {
  audio.loop();
  delay(5);
}