ESP32 Sound-Triggered Relay Demo

// ESP32 sound-triggered relay demo - not speech recognition
#include <driver/i2s.h>

const i2s_port_t I2S_PORT = I2S_NUM_0;
const int RELAY_PIN = 26;  // active LOW relay module input
const int LED_PIN = 25;
const int CLAP_THRESHOLD = 50000; // tune from Serial Monitor peak values
bool relayState = false;

void i2sInit() {
  i2s_config_t cfg = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
    .sample_rate = 16000,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
    .communication_format = I2S_COMM_FORMAT_STAND_I2S,
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = 4,
    .dma_buf_len = 256,
    .use_apll = false
  };
  i2s_pin_config_t pins = {
    .bck_io_num = 14,
    .ws_io_num = 15,
    .data_out_num = I2S_PIN_NO_CHANGE,
    .data_in_num = 32
  };
  i2s_driver_install(I2S_PORT, &cfg, 0, NULL);
  i2s_set_pin(I2S_PORT, &pins);
}

int32_t peak(int32_t *buf, size_t n) {
  int32_t mx = 0;
  for (size_t i = 0; i < n; i++) {
    int32_t v = abs(buf[i] >> 8);
    if (v > mx) mx = v;
  }
  return mx;
}

void setup() {
  Serial.begin(115200);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, HIGH); // active LOW relay off
  digitalWrite(LED_PIN, LOW);
  i2sInit();
  Serial.println("Sound-triggered relay demo ready. Use a low-voltage demo load.");
}

void loop() {
  int32_t samples[256];
  size_t bytesRead = 0;
  i2s_read(I2S_PORT, samples, sizeof(samples), &bytesRead, portMAX_DELAY);
  int32_t p = peak(samples, bytesRead / sizeof(int32_t));
  Serial.printf("Peak: %d\n", p);
  if (p > CLAP_THRESHOLD) {
    relayState = !relayState;
    digitalWrite(RELAY_PIN, relayState ? LOW : HIGH);
    digitalWrite(LED_PIN, relayState ? HIGH : LOW);
    Serial.printf("Relay: %s\n", relayState ? "ON" : "OFF");
    delay(500);
  }
}