#define TRIG_PIN 14 // ESP32 pin GIOP23 connected to Ultrasonic Sensor's TRIG pin
#define ECHO_PIN 27 // ESP32 pin GIOP22 connected to Ultrasonic Sensor's ECHO pin
#define LED 5

float duration_us, distance_cm;

void setup() {
  // begin serial port
  Serial.begin (115200);

  // configure the trigger pin to output mode
  pinMode(TRIG_PIN, OUTPUT);
  // configure the echo pin to input mode
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED, OUTPUT);
}

void loop() {
  // generate 10-microsecond pulse to TRIG pin
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // measure duration of pulse from ECHO pin
  duration_us = pulseIn(ECHO_PIN, HIGH);

  // calculate the distance
  distance_cm = 0.017 * duration_us;

  // print the value to Serial Monitor
  Serial.print("distance: ");
  Serial.print(distance_cm);
  Serial.println(" cm");

  if (distance_cm < 30)
    digitalWrite(LED, HIGH); //หลอดไฟติด
  else
    digitalWrite(LED, LOW); //หลอดไฟดับ

  delay(500);
}