Code for Edge Impluse Training

/*
 * ================================================================
 * VAANI NODE — XIAO ESP32S3 Sense
 * EDGE IMPULSE DATASET COLLECTOR
 * ================================================================
 */

#include <Arduino.h>
#include <driver/i2s.h>
#include "FS.h"
#include "SD.h"
#include "SPI.h"

// ─── PIN DEFINITIONS ────────────────────────────────────────────
#define MIC_DATA_PIN    41  
#define MIC_CLK_PIN     42  

#define SD_MOSI         9
#define SD_MISO         8
#define SD_SCK          7
#define SD_CS           21  

#define LED_PIN         3   

// ─── AUDIO CONFIG ───────────────────────────────────────────────
#define SAMPLE_RATE       16000
#define RECORD_SECONDS    1      // FIXED: Exactly 1 second for Edge Impulse
#define I2S_PORT          I2S_NUM_0
#define DMA_BUF_COUNT     8
#define DMA_BUF_LEN       512
#define CHUNK_SAMPLES     1024 

// ─── WAV HEADER WRITER ──────────────────────────────────────────
struct wav_header_t {
  char     riff_tag[4];
  uint32_t riff_length;
  char     wave_tag[4];
  char     fmt_tag[4];
  uint32_t fmt_length;
  uint16_t audio_format;
  uint16_t num_channels;
  uint32_t sample_rate;
  uint32_t byte_rate;
  uint16_t block_align;
  uint16_t bits_per_sample;
  char     data_tag[4];
  uint32_t data_length;
};

void buildWavHeader(wav_header_t* h, uint32_t dataBytes) {
  memcpy(h->riff_tag, "RIFF", 4);
  h->riff_length    = dataBytes + sizeof(wav_header_t) - 8;
  memcpy(h->wave_tag, "WAVE", 4);
  memcpy(h->fmt_tag,  "fmt ", 4);
  h->fmt_length     = 16;
  h->audio_format   = 1;
  h->num_channels   = 1;
  h->sample_rate    = SAMPLE_RATE;
  h->byte_rate      = SAMPLE_RATE * 2;
  h->block_align    = 2;
  h->bits_per_sample = 16;
  memcpy(h->data_tag, "data", 4);
  h->data_length    = dataBytes;
}

// ─── I2S (PDM MIC) SETUP ────────────────────────────────────────
void i2s_install() {
  const i2s_config_t cfg = {
    .mode             = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM),
    .sample_rate      = SAMPLE_RATE,
    .bits_per_sample  = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format   = I2S_CHANNEL_FMT_ONLY_LEFT,
    .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_I2S),
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count    = DMA_BUF_COUNT,
    .dma_buf_len      = DMA_BUF_LEN,
    .use_apll         = false,
    .tx_desc_auto_clear = false,
    .fixed_mclk       = 0
  };
  i2s_driver_install(I2S_PORT, &cfg, 0, NULL);
}

void i2s_setpin() {
  const i2s_pin_config_t pins = {
    .bck_io_num    = -1,          
    .ws_io_num     = MIC_CLK_PIN, 
    .data_out_num  = -1,
    .data_in_num   = MIC_DATA_PIN
  };
  i2s_set_pin(I2S_PORT, &pins);
}

// ─── LED HELPERS ────────────────────────────────────────────────
void ledOn()  { digitalWrite(LED_PIN, HIGH); }
void ledOff() { digitalWrite(LED_PIN, LOW);  }

void blinkConfirm(int times = 2, int ms = 100) {
  for (int i = 0; i < times; i++) {
    ledOn();  delay(ms);
    ledOff(); delay(ms);
  }
}

// ─── CORE RECORDING FUNCTION ────────────────────────────────────
void recordToSD() {
  ledOn(); 

  String fileName = "/v_" + String(millis()) + ".wav"; 

  File file = SD.open(fileName, FILE_WRITE);
  if (!file) {
    Serial.println("[SD] ERROR: Cannot open file!");
    ledOff();
    return;
  }

  wav_header_t header;
  file.write((uint8_t*)&header, sizeof(wav_header_t));

  int16_t  wav_buf[CHUNK_SAMPLES];   
  size_t   bytesIn    = 0;
  uint32_t totalBytes = 0;
  uint32_t endTime    = millis() + (RECORD_SECONDS * 1000);

  // Clear stale DMA buffers before recording
  i2s_read(I2S_PORT, wav_buf, sizeof(wav_buf), &bytesIn, 0); 
  delay(50); 
  
  Serial.println("[REC] *** RECORDING NOW ***");

  while (millis() < endTime) {
    esp_err_t res = i2s_read(I2S_PORT, wav_buf, sizeof(wav_buf), &bytesIn, portMAX_DELAY);
    if (res == ESP_OK && bytesIn > 0) {
      file.write((uint8_t*)wav_buf, bytesIn);
      totalBytes += bytesIn;
    }
  }

  buildWavHeader(&header, totalBytes);
  file.seek(0);
  file.write((uint8_t*)&header, sizeof(wav_header_t));
  file.close();

  Serial.printf("[SD] Saved: %s (%u bytes)\n", fileName.c_str(), totalBytes);

  ledOff();
  blinkConfirm(2); 
}

// ─── SETUP ──────────────────────────────────────────────────────
void setup() {
  Serial.begin(115200);
  delay(500);
  Serial.println("\n=== DATASET COLLECTOR STARTING ===");

  pinMode(LED_PIN, OUTPUT);
  ledOff();

  SPI.begin(SD_SCK, SD_MISO, SD_MOSI, SD_CS);
  if (!SD.begin(SD_CS)) {
    Serial.println("[SD] FAILED! Check wiring and ensure card is FAT32 formatted.");
    while (true) { ledOn(); delay(100); ledOff(); delay(100); }
  }
  Serial.printf("[SD] OK. Free: %llu MB\n", SD.totalBytes() / (1024 * 1024));

  i2s_install();
  i2s_setpin();
  i2s_start(I2S_PORT);
  Serial.println("[MIC] PDM microphone ready.");
}

// ─── MAIN LOOP ──────────────────────────────────────────────────
void loop() {
  Serial.println("\n--------------------------------");
  Serial.println("Get ready... Say your word in:");
  Serial.println("2...");
  delay(1000);
  Serial.println("1...");
  delay(1000);
  
  recordToSD();
  
  Serial.println("Good. Pausing for 2 seconds before next rep.");
  delay(2000);
}