#define ECHO_PIN 5
#define TRIG_PIN 4
#define ledMerah 8
#define ledKuning 7
#define ledHijau 6

void setup() {
  Serial.begin(115200);
  pinMode(ledMerah, OUTPUT);
  pinMode(ledKuning, OUTPUT);
  pinMode(ledHijau, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}
float readDistanceCM(){
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034/2;
  }

void loop() {
  float distance = readDistanceCM();

  Serial.print("Measured Distance : ");
  Serial.println(readDistanceCM());

  digitalWrite(ledMerah, LOW);
  digitalWrite(ledKuning, LOW);
  digitalWrite(ledHijau, LOW);

  if(distance < 50){
    Serial.println("Merah (Bahaya)");
    digitalWrite(ledMerah, HIGH);
  }
  else if(distance > 100){
    Serial.println("Kuning (Waspada)");
    digitalWrite(ledKuning, HIGH);
  }
  else{
    Serial.println("Hijau (Aman)");
    digitalWrite(ledHijau, HIGH);
  }

}