#define Echo 2
#define Trig 15
#define LED_1 21
#define LED_2 19
#define LED_3 18
#define LED_4 5

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(LED_1, OUTPUT);
  pinMode(LED_2, OUTPUT);
  pinMode(LED_3, OUTPUT);
  pinMode(LED_4, OUTPUT);
  pinMode(Trig, OUTPUT);
  pinMode(Echo, INPUT);
}

float readdistanceCM() {
  // Clears the trigPin condition
  digitalWrite(Trig, LOW);
  delayMicroseconds(2);
  // Sets the trigPin HIGH (ACTIVE) for 10 microseconds
  digitalWrite(Trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(Trig, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  long duration = pulseIn(Echo, HIGH);
  // Calculating the distance
  int distance = duration * 0.034 / 2; // Speed of sound wave divided by 2 (go and back)
  // Displays the distance on the Serial Monitor
  return distance;
}

void loop() {
  // put your main code here, to run repeatedly:

  Serial.print("Jarak: ");
  Serial.print(readdistanceCM());
  Serial.println(" cm");
  
  if (readdistanceCM() > 50){
  digitalWrite(LED_1, HIGH);
  digitalWrite(LED_2, LOW);
  digitalWrite(LED_3, LOW);
  digitalWrite(LED_4, LOW);
  }
  if (readdistanceCM() > 100){
  digitalWrite(LED_1, HIGH);
  digitalWrite(LED_2, HIGH);
  digitalWrite(LED_3, LOW);
  digitalWrite(LED_4, LOW);
  }
  if (readdistanceCM() > 200){
  digitalWrite(LED_1, HIGH);
  digitalWrite(LED_2, HIGH);
  digitalWrite(LED_3, HIGH);
  digitalWrite(LED_4, LOW);
  }
  if (readdistanceCM() > 300){
  digitalWrite(LED_1, HIGH);
  digitalWrite(LED_2, HIGH);
  digitalWrite(LED_3, HIGH);
  digitalWrite(LED_4, HIGH);
  }
  else
  {
    digitalWrite(LED_1, LOW);
    digitalWrite(LED_2, LOW);
    digitalWrite(LED_3, LOW);
    digitalWrite(LED_4, LOW);
  }
}