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/*
ESP32 I2S Microphone Sample
esp32-i2s-mic-sample.ino
Sample sound from I2S microphone, display on Serial Plotter
Requires INMP441 I2S microphone

DroneBot Workshop 2022
  https://dronebotworkshop.com
*/

// Include I2S driver
#include <driver/i2s.h>

// Connections to INMP441 I2S microphone
#define I2S_WS 26
#define I2S_SD 33
#define I2S_SCK 32

// Use I2S Processor 0
#define I2S_PORT I2S_NUM_0

// Define input buffer length
#define bufferLen 64
int16_t sBuffer[bufferLen];

void i2s_install() {
// Set up I2S Processor configuration
const i2s_config_t i2s_config = {
.mode = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX),
.sample_rate = 44100,
.bits_per_sample = i2s_bits_per_sample_t(16),
.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
.communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_STAND_I2S),
.intr_alloc_flags = 0,
.dma_buf_count = 8,
.dma_buf_len = bufferLen,
.use_apll = false
};

i2s_driver_install(I2S_PORT, &i2s_config, 0, NULL);
}

void i2s_setpin() {
// Set I2S pin configuration
const i2s_pin_config_t pin_config = {
.bck_io_num = I2S_SCK,
.ws_io_num = I2S_WS,
.data_out_num = -1,
.data_in_num = I2S_SD
};

i2s_set_pin(I2S_PORT, &pin_config);
}

void setup() {

// Set up Serial Monitor
  Serial.begin(115200);
  Serial.println(" ");

delay(1000);

// Set up I2S
  i2s_install();
  i2s_setpin();
  i2s_start(I2S_PORT);

delay(500);
}

void loop() {

// False print statements to "lock range" on serial plotter display
  // Change rangelimit value to adjust "sensitivity" 
  int rangelimit = 3000;
  Serial.print(rangelimit * -1);
  Serial.print(" ");
  Serial.print(rangelimit);
  Serial.print(" ");

// Get I2S data and place in data buffer
  size_t bytesIn = 0;
  esp_err_t result = i2s_read(I2S_PORT, &sBuffer, bufferLen, &bytesIn, portMAX_DELAY);

if (result == ESP_OK)
{
    // Read I2S data buffer
    int16_t samples_read = bytesIn / 8;
    if (samples_read > 0) {
      float mean = 0;
      for (int16_t i = 0; i < samples_read; ++i) {
        mean += (sBuffer[i]);
      }

// Average the data reading
      mean /= samples_read;

// Print to serial plotter
      Serial.println(mean);
    }
  }