const int triggerPin = 2;
const int echoPin = 3;
const int LED1 = 4;
const int LED2 = 5;
const int LED3 = 6;

long durasi;
int jarak;

void setup() {
pinMode(triggerPin, OUTPUT); 
pinMode(LED1, OUTPUT); 
pinMode(LED2, OUTPUT); 
pinMode(LED3, OUTPUT); 
pinMode(echoPin, INPUT);
  
Serial.begin(9600); 
}

void loop() {
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  durasi = pulseIn(echoPin, HIGH);
  jarak = durasi*0.034/2;
  
  if(jarak > 50){
    Serial.println("Jarak lebih dari 50cm");
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
  }else if(jarak <= 50 && jarak >= 20){
    Serial.println("Jarak berada diantara 20cm hingga 50cm");
    digitalWrite(LED2, HIGH);
    digitalWrite(LED1, LOW);
    digitalWrite(LED3, LOW);
  }else if(jarak < 20){
    Serial.println("Jarak kurang dari 20cm");
    digitalWrite(LED3, HIGH);
    digitalWrite(LED2, LOW);
    digitalWrite(LED1, LOW);
  }
}