const int LED_PIN = 12;
const int BUZZER_PIN = 13;
const int TRIG_PIN = 16;
const int ECHO_PIN = 17;

float DURATION, DISTANCE;

void setup() {
  Serial.begin(115200);

  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

void loop() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  DURATION = pulseIn(ECHO_PIN, HIGH);
  DISTANCE = (DURATION * 0.0343) / 2;

  Serial.println(DISTANCE);

  if (DISTANCE > 0 && DISTANCE <= 200) { 
    digitalWrite(LED_PIN, HIGH);
    tone(BUZZER_PIN, 1000); 
    delay(1000); 
  } else {
    digitalWrite(LED_PIN, LOW);
    noTone(BUZZER_PIN);
  }

  delay(100);
}