> ## Documentation Index
> Fetch the complete documentation index at: https://learn.pcbcupid.com/llms.txt
> Use this file to discover all available pages before exploring further.

> Interface the NAU8325 digital input Class-D audio amplifier and codec module with a Glyph ESP32 board over I²S to generate sine waves and stream SD card audio.

# Audio Codec

export const ShopHeader = ({title, url}) => <div style={{
  display: 'flex',
  justifyContent: 'flex-end',
  alignItems: 'center',
  width: '100%',
  marginBottom: '1rem',
  gap: '20px'
}}>
    <a href={url} target="_blank" rel="noopener noreferrer" style={{
  display: 'inline-flex',
  alignItems: 'center',
  backgroundColor: '#00b894',
  color: '#fff',
  padding: '8px 18px',
  borderRadius: '8px',
  textDecoration: 'none',
  fontSize: '0.95rem',
  fontWeight: 600,
  whiteSpace: 'nowrap',
  flexShrink: 0
}}>
      Shop now
    </a>
  </div>;

export const ImgGallery = ({images, modelUrl}) => {
  var [active, setActive] = useState(0);
  var [show3D, setShow3D] = useState(false);
  useEffect(function () {
    if (show3D || images.length <= 1) return;
    var t = setTimeout(function () {
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    }, 3500);
    return function () {
      clearTimeout(t);
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  var img = images[active];
  return <div style={{
    position: 'relative',
    background: 'linear-gradient(to bottom, #fff 0%, #fff 80%, #f8f8f8 100%)',
    borderRadius: '32px',
    border: '1px solid rgba(0,0,0,0.08)',
    overflow: 'hidden',
    marginTop: '0.75rem',
    marginBottom: '1.5rem'
  }}>
      <div style={{
    position: 'relative',
    height: '450px',
    display: 'flex',
    alignItems: 'center',
    justifyContent: 'center',
    background: '#fff',
    padding: '1rem'
  }}>
        {show3D && modelUrl ? <div ref={function (el) {
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    el._mv = true;
    function addMv() {
      var mv = document.createElement('model-viewer');
      mv.setAttribute('src', modelUrl);
      mv.setAttribute('camera-controls', '');
      mv.setAttribute('auto-rotate', '');
      mv.style.width = "100%";
      mv.style.height = "100%";
      mv.style.backgroundColor = "#f8f8f8";
      el.innerHTML = "";
      el.appendChild(mv);
    }
    if (window.customElements && window.customElements.get('model-viewer')) {
      addMv();
    } else {
      var s = document.createElement('script');
      s.src = "https://ajax.googleapis.com/ajax/libs/model-viewer/4.2.0/model-viewer.min.js";
      s.type = "module";
      s.onload = addMv;
      document.head.appendChild(s);
    }
  }} style={{
    width: "100%",
    height: "100%"
  }} /> : <img src={img && img.url} alt={img && img.label} loading="lazy" style={{
    maxWidth: '100%',
    maxHeight: '100%',
    objectFit: 'contain',
    borderRadius: '8px'
  }} />}
      </div>
      <div style={{
    display: 'flex',
    justifyContent: 'center',
    gap: '12px',
    padding: '1rem',
    background: '#eee',
    borderTop: '1px solid rgba(0,0,0,0.08)'
  }}>
        {images.map(function (img, idx) {
    return <button key={img.id || idx} onClick={function () {
      setActive(idx);
      setShow3D(false);
    }} style={{
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      borderRadius: '12px',
      border: !show3D && idx === active ? '1px solid #00b894' : '1px solid rgba(0,184,148,0.4)',
      background: !show3D && idx === active ? '#00b894' : '#fff',
      color: !show3D && idx === active ? '#fff' : '#000',
      cursor: 'pointer',
      fontSize: '0.75rem',
      fontWeight: 700,
      textTransform: 'uppercase',
      fontFamily: 'inherit'
    }}>
              {img.label}
            </button>;
  })}
        {modelUrl ? <button onClick={function () {
    setShow3D(true);
  }} style={{
    padding: '0.6rem 1.5rem',
    borderRadius: '12px',
    border: show3D ? '1px solid #00b894' : '1px solid rgba(0,184,148,0.4)',
    background: show3D ? '#00b894' : '#fff',
    color: show3D ? '#fff' : '#000',
    cursor: 'pointer',
    fontSize: '0.75rem',
    fontWeight: 700,
    textTransform: 'uppercase',
    fontFamily: 'inherit'
  }}>
            3D VIEW
          </button> : null}
      </div>
    </div>;
};

<ShopHeader title="Audio Codec & Amplifier" url="https://shop.pcbcupid.com/product/gm004/" />

<ImgGallery
  modelUrl="https://raw.githubusercontent.com/pcbcupid/pcbcupid-hardware-libraries/dev-anurag/GLB/gmod_nau8325.glb"
  images={[
{ url: 'https://files.pcbcupid.com/Documentation/Boards/g-mod/nau8325/Nau83235_illustration.avif', label: 'ILLUSTRATION VIEW', id: 'illustration' },
{ url: 'https://files.pcbcupid.com/Documentation/Boards/g-mod/nau8325/Nau83235-boardview.avif', label: 'BOARD VIEW', id: 'board' },
]}
/>

The **NAU8325** is a highly efficient digital input Class-D audio amplifier designed by Nuvoton Technology Corporation. It is well-suited for compact and battery-powered devices, including portable speakers, IoT devices, tablets, and smart audio systems. It features integrated digital-to-analog conversion, eliminating the need for an external DAC and reducing system complexity.

## How it Works

The NAU8325 receives digital audio via the **I²S (Inter-IC Sound)** protocol, which transfers pulse-code modulated (PCM) data between the MCU and the amplifier.

**I²S Signals:**

* **BCLK (Bit Clock):** Synchronizes each individual bit of audio data.
* **LRCK / WS (Word Select):** Indicates whether the data is for the left or right channel.
* **SD (Serial Data):** The real-time, synchronized audio stream.
* **MCLK (Master Clock):** Optional high-frequency clock for advanced timing (not always required).

## Recommended Audio Format

To ensure compatibility with the NAU8325 and ESP32 hardware, use the following audio settings:

| Feature         | Recommended Setting  |
| :-------------- | :------------------- |
| **Format**      | WAV or MP3           |
| **Sample Rate** | 44,100 Hz (Standard) |
| **Bit Depth**   | 16-bit               |
| **Channels**    | Stereo or Mono       |

<Tip>
  Tools like [Audacity](https://www.audacityteam.org/) can be used to convert audio files to these formats before playback.
</Tip>

## Key Features & Applications

### Key Features

* **Efficiency**: High-efficiency Class-D output with digital volume control.
* **Simplicity**: Direct I²S input, reducing PCB space and system cost.
* **Streaming**: Supports real-time streaming, sine wave generation, and SD card playback.
* **Versatility**: Ideal for IoT audio, portable speakers, and digital amplifiers.

### Applications

* IoT audio notification and voice prompts
* Portable Bluetooth / Wi-Fi smart speakers
* Embedded audio playback and music players
* Educational kits and sound synthesizers

***

## Example 1: Sine Wave Generation

### Pin Configuration

| Pin (NAU8325) | Glyph Board | Description            |
| :------------ | :---------- | :--------------------- |
| **WS**        | GPIO 8      | I2S Word Select (LRCK) |
| **BCK**       | GPIO 18     | I2S Bit Clock          |
| **DATA**      | GPIO 7      | I2S Serial Data        |
| **MCK**       | GPIO 19     | I2S Master Clock       |
| **SCL**       | GPIO 4      | I2C Clock              |
| **SDA**       | GPIO 5      | I2C Data               |

### Step 1: Hardware Required

1. GLYPH Board
2. NAU8325 Module
3. Speaker

### Step 2: Circuit Diagram

![nau8325\_circuit\_diagram](https://files.pcbcupid.com/Documentation/Boards/g-mod/nau8325/nau%20circuit%20daigram/pcbcupid_nau.jpg)

### Step 3: Code Setup

1. **Open Arduino IDE.**
2. **Install the required libraries:**
   * Install **[AudioTools](https://github.com/pschatzmann/arduino-audio-tools)**
   * Install **[PCBCUPID\_NAU8325](https://github.com/pcbcupid/PCBCUPID-NAU8325)**
3. **Copy and paste the following code into the Arduino IDE:**

```cpp theme={null}
/**
 * @file streams-generator-i2s.ino
 * @author Phil Schatzmann
 * @modified by Karthik E
 * @brief see https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-stream/streams-generator-i2s/README.md 
 * @copyright GPLv3
 */
 
#include <Wire.h>
#include "AudioTools.h"
#include "PCBCUPID_NAU8325.h" // install https://github.com/pcbcupid/PCBCUPID-NAU8325.git

AudioInfo info(44100, 2, 16);
SineWaveGenerator<int16_t> sineWave(32000); // subclass of SoundGenerator with max amplitude of 32000
GeneratedSoundStream<int16_t> sound(sineWave); // Stream generated from sine wave
I2SStream i2s;
StreamCopy copier(i2s, sound); // copies sound into i2s

// Use our NAU8325 codec configuration
TwoWire I2Cbus(0);
PCBCUPID_NAU8325 nau8325(I2Cbus);

void setup(void) {  
  // Open Serial 
  Serial.begin(115200);
  while(!Serial);
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);

  // Initialize I2C for NAU8325
  Serial.println("Checking I2C...");
  I2Cbus.begin(4, 5);

  delay(10);

  // Initialize NAU8325 codec
  if (!nau8325.begin()) {
    Serial.println("NAU8325 init failed");
    while (1);
  }
  nau8325.setVolume(0xFF, 0xFF); // Set max volume
  Serial.println("NAU8325 detected and configured!");

  // Start I2S
  Serial.println("starting I2S...");
  auto config = i2s.defaultConfig(TX_MODE);
  config.pin_ws = 8;
  config.pin_bck = 18;
  config.pin_data = 7;
  config.pin_mck = 19;
  config.is_master = true;
  config.use_apll = false;
  config.i2s_format = I2S_STD_FORMAT;
  config.copyFrom(info); 
  i2s.begin(config);

  // Setup sine wave
  sineWave.begin(info, N_B4);
  Serial.println("started...");
}

// Arduino loop - copy sound to out 
void loop() {
  copier.copy();
}
```

### Step 4: Upload the Code

1. **Connect the Board**
   * Connect your GLYPH board to your computer.

2. **Select the Board and Port**
   Do the following settings in your Arduino IDE:
   * `Tools > Board > esp32 > Pcbcupid GLYPH`
   * `Tools > Port` and select the port connected to your GLYPH.
   * `Tools > USB CDC on Boot >` ***Enabled***

<Warning>
  If `USB CDC on Boot` is not enabled, you won't see any serial output in the Serial Monitor.
</Warning>

3. **Upload the Code**
   * Click the upload button (➡️ icon) or use the shortcut `Ctrl + U` in Arduino IDE to upload the code to the board.

### Step 5: Observe the Output

* You should hear a continuous sine wave tone from the speaker connected to the NAU8325 module.

***

## Example 2: SD Card Audio Playback

### Pin Configuration

| Peripheral    | Signal | ESP32 GPIO Pin | Description      |
| :------------ | :----- | :------------- | :--------------- |
| **SD Card**   | SCK    | GPIO 21        | SPI Clock        |
|               | MISO   | GPIO 23        | SPI MISO         |
|               | MOSI   | GPIO 22        | SPI MOSI         |
|               | CS     | GPIO 19        | SPI Chip Select  |
| **NAU8325**   | SDA    | GPIO 4         | I2C Data         |
|               | SCL    | GPIO 5         | I2C Clock        |
| **I2S Audio** | BCK    | GPIO 6         | I2S Bit Clock    |
|               | WS     | GPIO 8         | I2S Word Select  |
|               | DATA   | GPIO 7         | I2S Serial Data  |
|               | MCLK   | GPIO 20        | I2S Master Clock |

### Step 1: Hardware Required

1. GLYPH Board
2. NAU8325 Module
3. Speaker
4. SD Card Module

### Step 2: Circuit Diagram

![nau8325\_with\_sdcard](https://files.pcbcupid.com/Documentation/Boards/g-mod/nau8325/nau%20circuit%20daigram/nau%20with%20sdcard/pcbcupid_nau8325_with_sdcard.jpg)

### Step 3: Code Setup

1. **Open Arduino IDE.**
2. **Install the required libraries:**
   * Install **[AudioTools](https://github.com/pschatzmann/arduino-audio-tools)**
   * Install **[PCBCUPID\_NAU8325](https://github.com/pcbcupid/PCBCUPID-NAU8325)**
3. **Copy and paste the following code into the Arduino IDE:**

```cpp theme={null}
#include <SPI.h>
#include <SD.h>
#include <Wire.h>
#include "AudioTools.h"
#include "AudioTools/AudioCodecs/CodecMP3Helix.h"
#include "PCBCUPID_NAU8325.h" // install https://github.com/pcbcupid/PCBCUPID-NAU8325.git

/* === Pin configuration === */

// SD Card configuration
#define MY_SCK 11
#define MY_MISO 3
#define MY_MOSI 2
#define MY_CS 1

// I2S (NAU8325) configuration
#define I2S_WS 24
#define I2S_BCK 25
#define I2S_DATA 23
#define I2S_MCLK 22

// === Audio settings ===
const uint32_t sample_rate = 44100; // sample_rate can be changed as per the song frequency (e.g. 48000, 32000, 16000, 8000, 96000, 12000, 64000)
const uint16_t ratio = 256;         // ratio supported by NAU8325 (e.g. 256, 400, 500)
const uint8_t bits = 16;            // bit depth (e.g. 16, 24, 32)

// === Objects ===
TwoWire I2Cbus(0);
PCBCUPID_NAU8325 nau8325(I2Cbus); 

// Audio Stream Configuration 
I2SStream i2s;
MP3DecoderHelix decoder;
EncodedAudioStream encodedStream(&i2s, &decoder);
StreamCopy copier;
File audioFile;

void setup() {
  Serial.begin(115200);
  delay(10);
  Serial.println("=== NAU8325 SD EXAMPLE ===");

  I2Cbus.begin(4, 5);

  if (!nau8325.begin()) {
    Serial.println("NAU8325 init failed");
    while (1)
      ;
  }

  nau8325.setVolume(0xFF, 0xFF); // Setting NAU8325 at maximum volume
  Serial.println("NAU8325 Turned ON");

  // SD card initialization
  SPI.begin(MY_SCK, MY_MISO, MY_MOSI, MY_CS);
  if (!SD.begin(MY_CS)) {
    Serial.println("SD card init failed");
    while (1)
      ;
  }

  audioFile = SD.open("/Dwapara.mp3"); // Enter the MP3 song name from your SD card followed by "/" e.g.: "/music.mp3"
  if (!audioFile || audioFile.isDirectory()) {
    Serial.println("MP3 file not found");
    while (1)
      ;
  }

  // I2S Config
  auto config = i2s.defaultConfig(TX_MODE);
  config.sample_rate = sample_rate;
  config.bits_per_sample = bits;
  config.channels = 2;
  config.pin_bck = I2S_BCK;
  config.pin_ws = I2S_WS;
  config.pin_data = I2S_DATA;
  config.pin_mck = I2S_MCLK;
  config.i2s_format = I2S_STD_FORMAT;
  config.use_apll = false;

  i2s.begin(config);
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);
  decoder.begin();
  copier.begin(encodedStream, audioFile);

  Serial.println("Playback started!");
}

void loop() {
  if (!copier.copy()) {
    // Sending empty values to auto turn off NAU8325
    Serial.println("Playback done. Sending silence...");
    int16_t zero = 0;
    for (int i = 0; i < 2048 * 2; i++) {
      i2s.write((uint8_t *)&zero, sizeof(zero));
    }
    while (1)
      ;
  }
}

// ========== SD Card File Listing ==========
void listDir(fs::FS &fs, const char *dirname, uint8_t levels) {
  Serial.printf("Listing directory: %s\n", dirname);
  File root = fs.open(dirname);
  if (!root || !root.isDirectory()) {
    Serial.println("Failed to open directory");
    return;
  }

  File file = root.openNextFile();
  while (file) {
    if (file.isDirectory()) {
      Serial.print("  DIR : ");
      Serial.println(file.name());
      if (levels) listDir(fs, file.path(), levels - 1);
    } else {
      Serial.print("  FILE: ");
      Serial.print(file.name());
      Serial.print("  SIZE: ");
      Serial.println(file.size());
    }
    file = root.openNextFile();
  }
}
```

### Step 4: Upload the Code

1. **Prepare SD Card**
   * Format the microSD card (FAT32 recommended).
   * Save your MP3 file as `/Dwapara.mp3` on the SD card root directory.
   * Insert the SD card into the SD card module.

2. **Connect the Board**
   * Connect your GLYPH board to your computer.

3. **Select the Board and Port**
   Do the following settings in your Arduino IDE:
   * `Tools > Board > esp32 > Pcbcupid GLYPH`
   * `Tools > Port` and select the port connected to your GLYPH.
   * `Tools > USB CDC on Boot >` ***Enabled***

<Warning>
  If `USB CDC on Boot` is not enabled, you won't see any serial output in the Serial Monitor.
</Warning>

4. **Upload the Code**
   * Click the upload button (➡️ icon) or use the shortcut `Ctrl + U` in Arduino IDE to upload the code to the board.

### Step 5: Observe the Output

* Open the Serial Monitor at **115200 baud**.
* The MP3 file stored on the SD card will play through the speaker connected to the NAU8325 module.