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

void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, OUTPUT);
  pinMode(ledMerah, OUTPUT);
  pinMode(ledKuning, OUTPUT);
  pinMode(ledHijau, OUTPUT);
}

 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("Measure distance:");
  Serial.println(readDistanceCM());

   if(distance <= 50){
   digitalWrite(ledMerah, HIGH);
   digitalWrite(ledKuning, LOW);
   digitalWrite(ledHijau, LOW);
  }
   else if(distance <= 100){
   digitalWrite(ledMerah, LOW);
   digitalWrite(ledKuning, HIGH);
   digitalWrite(ledHijau, LOW);
  }
   else{
   digitalWrite(ledMerah, LOW);
   digitalWrite(ledKuning, LOW);
   digitalWrite(ledHijau, HIGH);
  }
  delay(100);
}