Pinout — 3W amplifier MAX98357A I2S DAC

Pin	Signal	Description
`SPK -`	audio	Speaker - out
`SPK +`	audio	speaker + out
`LRC`	data	bottom header far-left hole
`BCLK`	SCK	bottom header left hole
`DIN`	data	bottom header center-left hole
`GAIN`	digital	bottom header center hole
`SD`	data	bottom header center-right hole
`GND`	ground	bottom header right-center hole
`VIN`	power	bottom header far-right hole

Wiring notes

I2S input pins: BCLK (bit clock), LRC (word select / LRCLK), DIN (serial data). Power: VIN (3.3V-5V), GND. Speaker output: connect SPK+ and SPK- directly to a passive speaker (4-8 ohm, up to 3W). ALWAYS include the speaker connection in wiring diagrams — the amplifier is useless without it. GAIN pin: leave unconnected for 9dB, connect to GND for 12dB, connect to VIN for 15dB. SD pin: leave unconnected or pull HIGH to enable; pull LOW or connect to GND to shut down.

Example wiring diagram — 3W amplifier MAX98357A I2S DAC

From	To	Wire
`board:5V`	`x1:VIN`	red
`board:GND`	`x1:GND`	black
`board:D9`	`x1:BCLK`	green
`board:D8`	`x1:LRC`	blue
`board:D10`	`x1:DIN`	yellow

Example Arduino code — 3W amplifier MAX98357A I2S DAC

This example was written and compile-checked for the arduino-uno. Codey Online adapts it to any other supported board for you.

#include <Arduino.h>

// Canonical beginner example for MAX98357A on Arduino Uno.
//
// Important:
// The Arduino Uno (AVR) cannot generate hardware I2S with the standard core,
// so this sketch demonstrates the wiring and control pins, then produces a very
// simple software-generated square-wave audio pattern on the data pin.
//
// Wiring used:
//   D9  -> BCLK
//   D8  -> LRC
//   D10 -> DIN
//   5V  -> VIN
//   GND -> GND

const uint8_t PIN_BCLK = 9;
const uint8_t PIN_LRC  = 8;
const uint8_t PIN_DIN  = 10;

const unsigned int toneHz = 440;
const unsigned long toneOnMs = 1000;
const unsigned long toneOffMs = 500;

void outputSquareWave(unsigned long durationMs, unsigned int frequencyHz) {
  // This does not create real I2S audio; it is only a simple beginner demo.
  // The MAX98357A requires an I2S-capable source for proper audio playback.
  unsigned long start = millis();
  unsigned long halfPeriodUs = 500000UL / frequencyHz;

  while (millis() - start < durationMs) {
    digitalWrite(PIN_DIN, HIGH);
    delayMicroseconds(halfPeriodUs);
    digitalWrite(PIN_DIN, LOW);
    delayMicroseconds(halfPeriodUs);
  }
}

void setup() {
  pinMode(PIN_BCLK, OUTPUT);
  pinMode(PIN_LRC, OUTPUT);
  pinMode(PIN_DIN, OUTPUT);

  digitalWrite(PIN_BCLK, LOW);
  digitalWrite(PIN_LRC, LOW);
  digitalWrite(PIN_DIN, LOW);

  Serial.begin(115200);
  Serial.println(F("MAX98357A example starting."));
  Serial.println(F("Arduino Uno does not support native I2S in the standard AVR core."));
  Serial.println(F("This sketch only demonstrates basic pin control on the labeled connections."));
}

void loop() {
  Serial.println(F("Tone ON"));
  outputSquareWave(toneOnMs, toneHz);

  Serial.println(F("Tone OFF"));
  digitalWrite(PIN_DIN, LOW);
  delay(toneOffMs);
}