Outputs and switching

DFPlayer Mini with ESP32

A DFPlayer Mini does the whole audio job by itself. It reads MP3 files from a microSD card and drives a small speaker, while your ESP32 only sends short serial commands. That suits a display board well, since no heavy decoding competes with the screen. It needs one UART and takes about 3 W into 4 Ω at 5 V, which is why power is the first thing to get right.

Do not run it from the same weak 5 V rail as a display. Loud sounds cause voltage drops, and those can reset the board. A separate supply helps, as does a 100 to 470 µF capacitor at the module. Put a 1 kΩ resistor between the ESP32 TX pin and the module's RX. Sources differ on why, but most recommend it. Connect the speaker between SPK1 and SPK2, not to ground.

Most 'module not found' reports come from the card or wiring. Use FAT32 or FAT16, because exFAT does not work, and insert the card before power-up. The file order is a trap: the player can sort by the order files were copied onto the card, so 0003.mp3 copied first plays as track one. Copy them one at a time in order. The player has no file system view from your code, so keep a list of tracks in the sketch. Sources disagree on how folders work, so start with a few files in the root. Many boards lack a free UART, so check before you buy. The example builds the 10-byte command itself, sets volume and plays track 1.

HardwareSerial player(1);
const int RX_PIN = 16, TX_PIN = 17;

void command(uint8_t cmd, uint16_t arg) {
  uint8_t f[10] = {0x7E, 0xFF, 0x06, cmd, 0x00,
                   (uint8_t)(arg >> 8), (uint8_t)arg, 0, 0, 0xEF};
  uint16_t sum = 0;
  for (int i = 1; i < 7; i++) sum += f[i];
  sum = -sum;                         // checksum
  f[7] = sum >> 8;
  f[8] = sum;
  player.write(f, 10);
}

void setup() {
  player.begin(9600, SERIAL_8N1, RX_PIN, TX_PIN);
  delay(2000);                        // card is read at start-up
  command(0x06, 15);                  // volume 0 to 30
  delay(100);
  command(0x03, 1);                   // play track 1
}

void loop() {}

Use this information at your own risk. It is for general guidance only: the example code compiles, but it has not been tested on every part, and modules differ between sellers. Check the manufacturer's data before you build. Product names belong to their owners, and LCD Ultra Pro is not affiliated with them. See our Terms.