const int LED_1 = 21;
const int LED_2 = 19;
const int LED_3 = 18;
const int LED_4 = 5;
const int buzz = 5;
const int TRIG = 2;
const int ECHO = 15;



float JARAK;

void Baca_Ultrasonic()
{
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  int duration = pulseIn(ECHO, HIGH);
  JARAK = duration * 0.034/2;
}


void setup() 
{
  pinMode(LED_1, OUTPUT);
  pinMode(LED_2, OUTPUT);
  pinMode(LED_3, OUTPUT);
  pinMode(LED_4, OUTPUT);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);

  digitalWrite(LED_1, LOW);
  digitalWrite(LED_2, LOW);
  digitalWrite(LED_3, LOW);
  digitalWrite(LED_4, LOW);
}

void loop() 
{
  Baca_Ultrasonic();
  if(JARAK >= 50 && JARAK <= 100 ) {
    digitalWrite(LED_1, HIGH); 
    digitalWrite(LED_2, LOW);
    digitalWrite(LED_3, LOW);
    digitalWrite(LED_4, LOW);
  }
  else if( JARAK >= 100 && JARAK <= 200 ) {
    digitalWrite(LED_1, HIGH);
    digitalWrite(LED_2, HIGH);
    digitalWrite(LED_3, LOW);
    digitalWrite(LED_4, LOW);
  }
  else if( JARAK >= 200 && JARAK <= 300 ) {
    digitalWrite(LED_1, HIGH); 
    digitalWrite(LED_2, HIGH);
    digitalWrite(LED_3, HIGH);
    digitalWrite(LED_4, LOW);
  }
  else if( JARAK >= 300 && JARAK <= 400 ) {
    digitalWrite(LED_1, HIGH);
    digitalWrite(LED_2, HIGH);
    digitalWrite(LED_3, HIGH);
    digitalWrite(LED_4, HIGH);
    tone(5,3000,200);
    delay(100);
  }
  else
  {
    digitalWrite(LED_1, LOW); 
    digitalWrite(LED_2, LOW);
    digitalWrite(LED_3, LOW);
    digitalWrite(LED_4, LOW); 
  }
}