#define trigPin 9
#define echoPin 10

#define ledHijau 2
#define ledKuning 3
#define ledMerah 4
#define buzzerPin 5

long duration;
int distanceCm;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  pinMode(ledHijau, OUTPUT);
  pinMode(ledKuning, OUTPUT);
  pinMode(ledMerah, OUTPUT);
  pinMode(buzzerPin, OUTPUT);

  Serial.begin(9600);
}

void loop() {
  // mulai pengukuran
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distanceCm = duration * 0.034 / 2;

  Serial.print("Jarak: ");
  Serial.print(distanceCm);
  Serial.println(" cm");

  // status LED dan buzzer
  if (distanceCm > 100) {                // Aman
    digitalWrite(ledHijau, HIGH);
    digitalWrite(ledKuning, LOW);
    digitalWrite(ledMerah, LOW);
    digitalWrite(buzzerPin, LOW);
  } 
  else if (distanceCm > 30) {            // Waspada
    digitalWrite(ledHijau, LOW);
    digitalWrite(ledKuning, HIGH);
    digitalWrite(ledMerah, LOW);
    digitalWrite(buzzerPin, LOW);
  } 
  else {                                // Kritis
    digitalWrite(ledHijau, LOW);
    digitalWrite(ledKuning, LOW);
    digitalWrite(ledMerah, HIGH);
    digitalWrite(buzzerPin, HIGH);
  }

  delay(200);
}