audio

16、音频功放播放示例 示例功能： 示例中使用预生成的1kHz正弦波数据，实际使用时可以替换为WAV文件转换的PCM数据，生成音频。正确配置I2S后，通过i2s_write函数将音频数据发送到I2S接口。驱动MAX98357对音频进行播放。以下示例中采用音频功放播放一段旋律。 配置I2S需注意： a.使用主模式发送（I2S_MODE_MASTER | I2S_MODE_TX） b.16位采样位数，44100Hz采样率 c.单声道左声道输出

硬件连接（默认已连接详细参考表格：引脚占用表） ●BCLK → ESP32的GPIO39 ●LRC → ESP32的GPIO40 ●DIN → ESP32的GPIO38 ●GND → ESP32的GND ●V → ESP32的3.3V ●Mode → 悬空 ●GAIN → 悬空（默认使用3dB增益）

#include <Arduino.h>
#include <driver/i2s.h>

// 引脚定义
#define I2S_BCLK  39
#define I2S_LRC   40
#define I2S_DOUT  38

// I2S配置
#define SAMPLE_RATE     44100
#define SAMPLE_BITS     16
#define AMPLITUDE       0.3

// 音符频率定义 (Hz)
#define NOTE_C4  261.63
#define NOTE_D4  293.66
#define NOTE_E4  329.63
#define NOTE_F4  349.23
#define NOTE_G4  392.00
#define NOTE_A4  440.00
#define NOTE_B4  493.88

// 节拍时长定义 (ms)
#define Q 250  // 四分音符
#define H 500  // 二分音符

// 小星星前奏音符序列
struct Note {
  float freq;
  uint32_t duration;
};

Note melody[] = {
  {NOTE_C4, Q}, {NOTE_C4, Q}, {NOTE_G4, Q}, {NOTE_G4, Q},
  {NOTE_A4, Q}, {NOTE_A4, Q}, {NOTE_G4, H},
  {NOTE_F4, Q}, {NOTE_F4, Q}, {NOTE_E4, Q}, {NOTE_E4, Q},
  {NOTE_D4, Q}, {NOTE_D4, Q}, {NOTE_C4, H}
};

const int notesCount = sizeof(melody) / sizeof(melody[0]);
int currentNote = 0;
uint32_t noteStartTime = 0;

// I2S初始化
void setup() {
  Serial.begin(115200);
  
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX),
    .sample_rate = SAMPLE_RATE,
    .bits_per_sample = (i2s_bits_per_sample_t)SAMPLE_BITS,
    .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
    .communication_format = I2S_COMM_FORMAT_STAND_I2S,
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = 8,
    .dma_buf_len = 512,
    .use_apll = false
  };

  i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_BCLK,
    .ws_io_num = I2S_LRC,
    .data_out_num = I2S_DOUT,
    .data_in_num = I2S_PIN_NO_CHANGE
  };

  i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
  i2s_set_pin(I2S_NUM_0, &pin_config);
}

// 动态生成正弦波
void generate_sine(int16_t* buffer, size_t samples, float freq) {
  static float phase = 0.0;
  float phaseIncrement = 2 * PI * freq / SAMPLE_RATE;
  
  for (int i = 0; i < samples; i++) {
    buffer[i] = AMPLITUDE * 32767.0 * sin(phase);
    phase += phaseIncrement;
    if (phase >= 2 * PI) phase -= 2 * PI;
  }
}

void loop() {
  const size_t bufferSize = 256;
  int16_t audioBuffer[bufferSize];
  size_t bytesWritten;

  // 当前音符播放时间检查
  if (millis() - noteStartTime >= melody[currentNote].duration) {
    currentNote = (currentNote + 1) % notesCount;  // 循环播放
    noteStartTime = millis();
  }

  // 生成当前音符的音频
  generate_sine(audioBuffer, bufferSize, melody[currentNote].freq);

  // 发送到I2S
  i2s_write(I2S_NUM_0, 
           audioBuffer, 
           bufferSize * sizeof(int16_t),
           &bytesWritten, 
           portMAX_DELAY);
}