#define ECHO_PIN 5
#define TRIG_PIN 3
#define Merah 8
#define Kuning 7
#define Hijau 6

float X=400/397.63;
float jarak=0;

void baca_jarak()
{
  //Generate ultrasonic signal
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  //Read ultrasonic signal
  int durasi = pulseIn(ECHO_PIN, HIGH);
  jarak = durasi * 0.034 * X / 2;
}

void setup() {
  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(Merah, OUTPUT);
  pinMode(Kuning, OUTPUT);
  pinMode(Hijau, OUTPUT);
}

void loop() {
  baca_jarak();

  Serial.print("Jarak: ");
  Serial.print(jarak);
  Serial.println(" CM");
  digitalWrite(Merah, LOW);
  digitalWrite(Kuning, LOW);
  digitalWrite(Hijau, LOW);
  if(jarak < 50)
  {
    Serial.println("Merah");
    digitalWrite(Merah, HIGH);
  }
  else if(jarak < 100)
  {
    Serial.println("Kuning");
    digitalWrite(Kuning, HIGH);
  }
  else
  {
    Serial.println("Hijau");
    digitalWrite(Hijau, HIGH);
  }
  delay(500);
}