#define lampu1 21
#define lampu2 19
#define lampu3 18
#define lampu4 5
#define echo_pin 2
#define trig_pin 15
#define distance_threshold 50

void setup() {
  Serial.begin(115200);
  pinMode(trig_pin, OUTPUT);
  pinMode(echo_pin, INPUT);
  pinMode(lampu1, OUTPUT);
  pinMode(lampu2, OUTPUT);
  pinMode(lampu3, OUTPUT);
  pinMode(lampu4, OUTPUT);
}

void loop() {
  digitalWrite(trig_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_pin, LOW);

  int duration = pulseIn(echo_pin, HIGH);

  float distance = 0.017 * duration;

  if(distance<100){
    digitalWrite(lampu1, HIGH);
    digitalWrite(lampu2, LOW);
    digitalWrite(lampu3, LOW);
    digitalWrite(lampu4, LOW);
  }
  else if(distance>=100, distance<200){
    digitalWrite(lampu1, LOW);
    digitalWrite(lampu2, HIGH);
    digitalWrite(lampu3, LOW);
    digitalWrite(lampu4, LOW);
  }
  else if(distance>=200, distance <300){
    digitalWrite(lampu1, LOW);
    digitalWrite(lampu2, LOW);
    digitalWrite(lampu4, LOW);
    digitalWrite(lampu3, HIGH);
  }
  else if(distance>=300){
    digitalWrite(lampu1, LOW);
    digitalWrite(lampu2, LOW);
    digitalWrite(lampu3, LOW);
    digitalWrite(lampu4, HIGH);
  }
  else{
    digitalWrite(lampu1, LOW);
    digitalWrite(lampu2, LOW);
    digitalWrite(lampu3, LOW);
    digitalWrite(lampu4, LOW);
  }
}