int led4 = 21;
int led3 = 19;
int led2 = 18;
int led1 = 5;

#define trig_pin 15
#define echo_pin 2

#define buzz 4

void setup() {
  Serial.begin(115200);
  Serial.println("Memulai rangkaian projects ..");
  delay(1000);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(trig_pin, OUTPUT);
  pinMode(buzz, OUTPUT);
  pinMode(echo_pin, INPUT);
}

float readDistance() {
  digitalWrite(trig_pin, LOW);
  delayMicroseconds(5);
  digitalWrite(trig_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_pin, LOW);
  int duration = pulseIn(echo_pin, HIGH);
  return duration * 0.034 / 2;
}

void loop() {
  int distance = readDistance();
  if (distance > 300) {
    digitalWrite(led1, HIGH);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, HIGH);
    digitalWrite(led4, HIGH);
    tone(4, 262, 250);
  } else if (distance > 200) {
    digitalWrite(led1, HIGH);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, HIGH);
    digitalWrite(led4, LOW);
  } else if (distance > 100) {
    digitalWrite(led1, HIGH);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, LOW);
    digitalWrite(led4, LOW);
  } else if (distance > 50) {
    digitalWrite(led1, HIGH);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    digitalWrite(led4, LOW);
  } else {
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    digitalWrite(led4, LOW);
  }

  Serial.print("Jarak: ");
  Serial.print(distance);
  Serial.println(" cm");
  delay(1000);
}