MAX98357A I2S audio amplifier with ESP32

Supply 3.3-5 V Bus GPIO

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
LRC	SPI chip select	D25	I2S word select (LRCLK), not SPI
BCLK	SPI clock	D26	I2S bit clock, not SPI
DIN	Input (the ESP32 drives it)	D27	I2S audio data from the ESP32
GAIN	Not wired to the ESP32	—	Leave unconnected for 9 dB
SD	Not wired to the ESP32	—	Shutdown / channel select. Leave unconnected
GND	Ground	GND
VIN	Power	3V3	2.5 to 5.5 V; 5 V gives more volume

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

void setup() { pinMode(27, OUTPUT); }  // DIN

void loop() {
  digitalWrite(27, HIGH);
  delay(500);
  digitalWrite(27, LOW);
  delay(500);
}

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.