Adafruit PCM5122 I2S DAC

Easy and powerful I2S DAC

by Liz Clark

published September 26, 2025, last edited September 26, 2025

posted in Adafruit Products Raspberry Pi Arduino Compatibles CircuitPython Breakout Boards/ Amplifiers/Sound

Beginner

Product guide

Arduino - Hardware Mode

Using the PCM5122 breakout in hardware mode with Arduino involves wiring up the breakout to your Arduino-compatible microcontroller and running the provided example code.

If you want to use this DAC with its I2C driver, you can reference the Arduino - I2C Mode page.

Wiring

You can power the I2S DAC with 3.3 to 5VDC, however, the data lines are 3.3V logic only. You'll want to use a 3.3V logic level board.

Here is an Adafruit Metro RP2040 wired up to the DAC for hardware control mode:

Board 3.3V to DAC VIN (red wire)
Board GND to DAC GND (black wire)
Board D9 to DAC BCK (green wire)
Board D10 to DAC WSEL (white wire)
Board D11 to DAC DIN (orange wire)

No additional libraries are needed for this example.

Example Code

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// SPDX-FileCopyrightText: 2025 Ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT

#include <I2S.h>
#include <math.h>

#define pBCLK D9   // BITCLOCK - I2S clock
#define pWS   D10  // LRCLOCK - Word select
#define pDOUT D11  // DATA - I2S data

// Create I2S port
I2S i2s(OUTPUT);

const int frequency = 440; // frequency of square wave in Hz
const int amplitude = 500; // amplitude of square wave
const int sampleRate = 16000; // 16 KHz is a good quality

const int halfWavelength = (sampleRate / frequency); // half wavelength of square wave

int16_t sample = amplitude; // current sample value
int count = 0;

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println(F("Adafruit PCM51xx Hardware Mode Test"));

  // Initialize I2S peripheral
  Serial.println("Initializing I2S...");
  i2s.setBCLK(pBCLK);
  i2s.setDATA(pDOUT);
  i2s.setBitsPerSample(16);
  
  // Start I2S at the sample rate
  if (!i2s.begin(sampleRate)) {
    Serial.println("Failed to initialize I2S!");
  }
  
}

void loop() {
  if (count % halfWavelength == 0) {
    // invert the sample every half wavelength count multiple to generate square wave
    sample = -1 * sample;
  }

  // write the same sample twice, once for left and once for the right channel
  i2s.write(sample);
  i2s.write(sample);

  // increment the counter for the next sample
  count++;
}

// SPDX-FileCopyrightText: 2025 Ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT

#include <I2S.h>
#include <math.h>

#define pBCLK D9   // BITCLOCK - I2S clock
#define pWS   D10  // LRCLOCK - Word select
#define pDOUT D11  // DATA - I2S data

// Create I2S port
I2S i2s(OUTPUT);

const int frequency = 440; // frequency of square wave in Hz
const int amplitude = 500; // amplitude of square wave
const int sampleRate = 16000; // 16 KHz is a good quality

const int halfWavelength = (sampleRate / frequency); // half wavelength of square wave

int16_t sample = amplitude; // current sample value
int count = 0;

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println(F("Adafruit PCM51xx Hardware Mode Test"));

  // Initialize I2S peripheral
  Serial.println("Initializing I2S...");
  i2s.setBCLK(pBCLK);
  i2s.setDATA(pDOUT);
  i2s.setBitsPerSample(16);
  
  // Start I2S at the sample rate
  if (!i2s.begin(sampleRate)) {
    Serial.println("Failed to initialize I2S!");
  }
  
}

void loop() {
  if (count % halfWavelength == 0) {
    // invert the sample every half wavelength count multiple to generate square wave
    sample = -1 * sample;
  }

  // write the same sample twice, once for left and once for the right channel
  i2s.write(sample);
  i2s.write(sample);

  // increment the counter for the next sample
  count++;
}

View on GitHub

Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You'll see the I2S peripheral initialized. In the loop, a sine tone will play through the 3.5 mm jack output.