#define ECHO_PIN 15
#define TRIG_PIN 2
#define led1 21
#define led2 19
#define led3 18
#define led4 5
#define buzzer 12

void setup() {
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034 / 2;
}

void loop() {
  float distance = readDistanceCM();  
  Serial.print("Jarak: ");
  Serial.println(distance);

  if(distance > 50){
    digitalWrite(led1, HIGH);
  }else{
    digitalWrite(led1, LOW);  
  }
  if(distance > 100){
    digitalWrite(led2, HIGH);
  }else{
    digitalWrite(led2, LOW);
  }
  if(distance > 200){
    digitalWrite(led3, HIGH);
  }
  else{
    digitalWrite(led3, LOW);
  }
  if(distance > 300){
    digitalWrite(led4, HIGH);
    tone(buzzer, 500);
  }
  else{
    digitalWrite(led4, LOW);
    tone(buzzer, LOW);
  }

  delay(100);
}