Using the PCM5122 breakout in I2C Mode with Arduino involves wiring up the breakout to your Arduino-compatible microcontroller, installing the Adafruit_PCM51xx library, and running the provided example code.
If you want to get up and running quickly without I2C, you can use this DAC in hardware mode as shown on the Arduino - Hardware 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 I2C control mode:
- Board 3.3V to DAC VIN (red wire)
- Board GND to DAC GND (black wire)
- Board SCL to DAC SCL (yellow wire)
- Board SDA to DAC SDA (blue wire)
- Board D9 to DAC BCK (green wire)
- Board D10 to DAC WSEL (white wire)
- Board D11 to DAC DIN (orange wire)
- Board 3.3V to DAC MOD2 (pink wire)
Library Installation
You can install the Adafruit_PCM51xx library for Arduino using the Library Manager in the Arduino IDE.
Click the Manage Libraries ... menu item, search for Adafruit_PCM51xx, and select the Adafruit PCM51xx library:
If asked about dependencies, click "Install all".
If the "Dependencies" window does not come up, then you already have the dependencies installed.
If the dependencies are already installed, you must make sure you update them through the Arduino Library Manager before loading the example!
// SPDX-FileCopyrightText: 2025 Ladyada for Adafruit Industries
//
// SPDX-License-Identifier: MIT
/*!
*
* Basic test example for the Adafruit PCM5122
*
* Written by Limor 'ladyada' Fried with assistance from Claude Code
* for Adafruit Industries.
*
* MIT license, all text here must be included in any redistribution.
*/
#include <Adafruit_PCM51xx.h>
#include <I2S.h>
#include <math.h>
Adafruit_PCM51xx pcm;
#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 Test"));
// I2C mode (default)
if (!pcm.begin()) {
Serial.println(F("Could not find PCM51xx, check wiring!"));
while (1) delay(10);
}
// Hardware SPI mode (uncomment to use)
// if (!pcm.begin(10, &SPI)) { // CS pin 10
// Serial.println(F("Could not find PCM51xx over SPI, check wiring!"));
// while (1) delay(10);
// }
// Software SPI mode (uncomment to use)
// if (!pcm.begin(10, 11, 12, 13)) { // CS, MOSI, MISO, SCLK
// Serial.println(F("Could not find PCM51xx over software SPI, check wiring!"));
// while (1) delay(10);
// }
Serial.println(F("PCM51xx initialized successfully!"));
// Set I2S format to I2S
Serial.println(F("Setting I2S format"));
pcm.setI2SFormat(PCM51XX_I2S_FORMAT_I2S);
// Read and display current format
pcm51xx_i2s_format_t format = pcm.getI2SFormat();
Serial.print(F("Current I2S format: "));
switch (format) {
case PCM51XX_I2S_FORMAT_I2S:
Serial.println(F("I2S"));
break;
case PCM51XX_I2S_FORMAT_TDM:
Serial.println(F("TDM/DSP"));
break;
case PCM51XX_I2S_FORMAT_RTJ:
Serial.println(F("Right Justified"));
break;
case PCM51XX_I2S_FORMAT_LTJ:
Serial.println(F("Left Justified"));
break;
default:
Serial.println(F("Unknown"));
break;
}
// Set I2S word length to 32-bit
Serial.println(F("Setting I2S word length"));
pcm.setI2SSize(PCM51XX_I2S_SIZE_16BIT);
// Read and display current word length
pcm51xx_i2s_size_t size = pcm.getI2SSize();
Serial.print(F("Current I2S word length: "));
switch (size) {
case PCM51XX_I2S_SIZE_16BIT:
Serial.println(F("16 bits"));
break;
case PCM51XX_I2S_SIZE_20BIT:
Serial.println(F("20 bits"));
break;
case PCM51XX_I2S_SIZE_24BIT:
Serial.println(F("24 bits"));
break;
case PCM51XX_I2S_SIZE_32BIT:
Serial.println(F("32 bits"));
break;
default:
Serial.println(F("Unknown"));
break;
}
// Set error detection bits
if (!pcm.ignoreFSDetect(true) || !pcm.ignoreBCKDetect(true) || !pcm.ignoreSCKDetect(true) ||
!pcm.ignoreClockHalt(true) || !pcm.ignoreClockMissing(true) || !pcm.disableClockAutoset(false) ||
!pcm.ignorePLLUnlock(true)) {
Serial.println(F("Error detection failed to configure"));
}
// Enable PLL
Serial.println(F("Enabling PLL"));
pcm.enablePLL(true);
// Check PLL status
bool pllEnabled = pcm.isPLLEnabled();
Serial.print(F("PLL enabled: "));
Serial.println(pllEnabled ? F("Yes") : F("No"));
// Set PLL reference to BCK
Serial.println(F("Setting PLL reference"));
pcm.setPLLReference(PCM51XX_PLL_REF_BCK);
// Read and display current PLL reference
pcm51xx_pll_ref_t pllRef = pcm.getPLLReference();
Serial.print(F("Current PLL reference: "));
switch (pllRef) {
case PCM51XX_PLL_REF_SCK:
Serial.println(F("SCK"));
break;
case PCM51XX_PLL_REF_BCK:
Serial.println(F("BCK"));
break;
case PCM51XX_PLL_REF_GPIO:
Serial.println(F("GPIO"));
break;
default:
Serial.println(F("Unknown"));
break;
}
// Set DAC clock source to PLL
Serial.println(F("Setting DAC source"));
pcm.setDACSource(PCM51XX_DAC_CLK_PLL);
// Read and display current DAC source
pcm51xx_dac_clk_src_t dacSource = pcm.getDACSource();
Serial.print(F("Current DAC source: "));
switch (dacSource) {
case PCM51XX_DAC_CLK_MASTER:
Serial.println(F("Master clock (auto-select)"));
break;
case PCM51XX_DAC_CLK_PLL:
Serial.println(F("PLL clock"));
break;
case PCM51XX_DAC_CLK_SCK:
Serial.println(F("SCK clock"));
break;
case PCM51XX_DAC_CLK_BCK:
Serial.println(F("BCK clock"));
break;
default:
Serial.println(F("Unknown"));
break;
}
// Test auto mute (default turn off)
Serial.println(F("Setting auto mute"));
pcm.setAutoMute(false);
// Read and display current auto mute status
bool autoMuteEnabled = pcm.getAutoMute();
Serial.print(F("Auto mute: "));
Serial.println(autoMuteEnabled ? F("Enabled") : F("Disabled"));
// Test mute (default do not mute)
Serial.println(F("Setting mute"));
pcm.mute(false);
// Read and display current mute status
bool muteEnabled = pcm.isMuted();
Serial.print(F("Mute: "));
Serial.println(muteEnabled ? F("Enabled") : F("Disabled"));
// Check DSP boot status and power state
Serial.print(F("DSP boot done: "));
Serial.println(pcm.getDSPBootDone() ? F("Yes") : F("No"));
pcm51xx_power_state_t powerState = pcm.getPowerState();
Serial.print(F("Power state: "));
switch (powerState) {
case PCM51XX_POWER_POWERDOWN:
Serial.println(F("Powerdown"));
break;
case PCM51XX_POWER_WAIT_CP_VALID:
Serial.println(F("Wait for CP voltage valid"));
break;
case PCM51XX_POWER_CALIBRATION_1:
case PCM51XX_POWER_CALIBRATION_2:
Serial.println(F("Calibration"));
break;
case PCM51XX_POWER_VOLUME_RAMP_UP:
Serial.println(F("Volume ramp up"));
break;
case PCM51XX_POWER_RUN_PLAYING:
Serial.println(F("Run (Playing)"));
break;
case PCM51XX_POWER_LINE_SHORT:
Serial.println(F("Line output short / Low impedance"));
break;
case PCM51XX_POWER_VOLUME_RAMP_DOWN:
Serial.println(F("Volume ramp down"));
break;
case PCM51XX_POWER_STANDBY:
Serial.println(F("Standby"));
break;
default:
Serial.println(F("Unknown"));
break;
}
// Check PLL lock status
bool pllLocked = pcm.isPLLLocked();
Serial.print(F("PLL locked: "));
Serial.println(pllLocked ? F("Yes") : F("No"));
// Set volume to -6dB on both channels
Serial.println(F("Setting volume"));
pcm.setVolumeDB(-6.0, -6.0);
// Read and display current volume
float leftVol, rightVol;
pcm.getVolumeDB(&leftVol, &rightVol);
Serial.print(F("Current volume - Left: "));
Serial.print(leftVol, 1);
Serial.print(F("dB, Right: "));
Serial.print(rightVol, 1);
Serial.println(F("dB"));
// 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++;
}
Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You'll see the PCM5122 recognized over I2C. Then, you'll see the setup parameters print out to the Serial Monitor. In the loop, a sine tone will play through the 3.5 mm jack output.
Page last edited September 26, 2025
Text editor powered by tinymce.
