【Arduino 动手做】使用 ESP32 采样音频的最佳方法 简单

#define NumberofSamples 8

#define audio_in_Pin 32
int Samplefrequency=44100;
int sampling_period  = round(1000000*(1.0/Samplefrequency));
int ADCValue[8];

void setup(){
Serial.begin(115200);
}

void loop(){
    for (int i=0 ; i < NumberofSamples; i++) {
      unsigned long newTime= micros();  
      ADCValue[i]=analogRead(audio_in_Pin);
       while( micros() <   newTime+ sampling_period ){ // do nothing}
     }
 // now the buffer ADCValue is filled with 8 samples of ADC 
 // data that was  sampled at 10 Khz

 // now you can process your audio samples
 for(int i=0;i<NumberofSamples;i++){
  Serial.printf("%7d ",ADCValue[i]);
 }
 Serial.printf("\n");
 // FFT processing
 // Displaying of data 
 // etc.

 }

}

#include <arduinoFFT.h>
#include <driver/i2s.h>
#define ADC_INPUT ADC1_CHANNEL_0 //pin 32
#define ARRAYSIZE(a)    (sizeof(a)/sizeof(a[0]))
const int numBands =8;

const double samplingFrequency = 10000;
const int SAMPLEBLOCK = 8;
const i2s_port_t I2S_PORT = I2S_NUM_0;
uint16_t offset = (int)ADC_INPUT * 0x1000 + 0xFFF;
uint16_t samples[SAMPLEBLOCK];

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Setting up Audio Input I2S");
  setupI2S();
  Serial.println("Audio input setup completed");
  delay(1000);
}

void loop() {
  size_t bytesRead = 0;
                              i2s_read(I2S_PORT, 
                                      (void*)samples, 
                                      sizeof(samples),
                                      &bytesRead,
                                      portMAX_DELAY); // no timeout
   if (bytesRead != sizeof(samples))
        {
            Serial.printf("Could only read %u bytes of %u in FillBufferI2S()\n", bytesRead, sizeof(samples));
           // return;
        }
                                      
  for (uint16_t i = 0; i < ARRAYSIZE(samples); i++) {
       // samples[i] &FFF
        Serial.printf("%7d,",offset-samples[i]); 
        
  }
    Serial.printf("\n"); 
}  
 
void setupI2S() {
  Serial.println("Configuring I2S...");
  esp_err_t err;
  // The I2S config as per the example
  const i2s_config_t i2s_config = { 
      .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN),
      .sample_rate = samplingFrequency,                        
      .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, // could only get it to work with 32bits
      .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT, // although the SEL config should be left, it seems to transmit on right
      .communication_format = I2S_COMM_FORMAT_I2S_MSB,
      .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,     // Interrupt level 1
      .dma_buf_count = 4,                           // number of buffers
      .dma_buf_len = SAMPLEBLOCK,                     // samples per buffer
      .use_apll = false//,
     // .tx_desc_auto_clear = false,
     // .fixed_mclk = 1
  };

 err = adc_gpio_init(ADC_UNIT_1, ADC_CHANNEL_0); //step 1
  if (err != ESP_OK) {
    Serial.printf("Failed setting up adc channel: %d\n", err);
    while (true);
  }
 
  err = i2s_driver_install(I2S_NUM_0, &i2s_config,  0, NULL);  //step 2
  if (err != ESP_OK) {
    Serial.printf("Failed installing driver: %d\n", err);
    while (true);
  }

  err = i2s_set_adc_mode(ADC_UNIT_1, ADC_INPUT);
    if (err != ESP_OK) {
    Serial.printf("Failed setting up adc mode: %d\n", err);
    while (true);
  }
  

  
  Serial.println("I2S driver installed.");
}