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

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);  
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  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() {
  // put your main code here, to run repeatedly:
  float distance = readDistanceCM();

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

  delay(100);
  if(distance <= 50){
    digitalWrite(ledMerah, HIGH);
    digitalWrite(ledKuning, LOW);
    digitalWrite(ledHijau, LOW);
    delay(500); 
  }
  else if(distance > 50 && distance <= 100 ){
    digitalWrite(ledKuning, HIGH);
    digitalWrite(ledMerah, LOW);
    digitalWrite(ledHijau, LOW);
    delay(500); 
  } else {
    digitalWrite(ledHijau, HIGH);
    digitalWrite(ledKuning, LOW);
    digitalWrite(ledMerah, LOW);
    delay(500);
  }                  

}