#define TRIG_PIN 9

#define ECHO_PIN 10

#define LED_PIN 6

void setup() {

  Serial.begin(9600);

  pinMode(TRIG_PIN, OUTPUT);

  pinMode(ECHO_PIN, INPUT);

  pinMode(LED_PIN, OUTPUT);

}

void loop() {

  long duration, distance;

  // 초음파 센서로 거리 측정

  digitalWrite(TRIG_PIN, LOW);

  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);

  delayMicroseconds(10);

  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH);

  distance = (duration / 2) * 0.0343;

  Serial.print("Distance: ");

  Serial.print(distance);

  Serial.println(" cm");

  // 거리에 따라 LED 제어

  if (distance < 30) {

    digitalWrite(LED_PIN, HIGH); // 거리가 10cm 미만이면 LED 켜기

  } else {

    digitalWrite(LED_PIN, LOW); // 거리가 10cm 이상이면 LED 끄기

  }

  delay(200);

}