#define echoPin 2
#define trigPin 3

int maximumRange = 400;  // Adjusted to the maximum reliable range of the sensor
int minimumRange = 2;    // A realistic minimum range to avoid zero or negative readings
long duration, distance;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
}

void loop() {
  // Trigger the ultrasonic burst
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the echo pulse
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance based on the duration
  distance = duration / 58.2;

  // Check if the distance is within the measurable range of the sensor
  if (distance > maximumRange || distance < minimumRange) {
    Serial.println("Di Luar jangkauan");
  } else {
    // Print the measured distance to the serial monitor
    Serial.print("Jarak: ");
    Serial.print(distance);
    Serial.println(" cm");

    // Control the LEDs based on the distance
    if (distance <= 100) {
      digitalWrite(11, HIGH);
      digitalWrite(10, LOW);
      digitalWrite(9, LOW);
    } else if (distance > 100 && distance < 200) {
      digitalWrite(11, LOW);
      digitalWrite(10, HIGH);
      digitalWrite(9, LOW);
    } else if (distance >= 200) {
      digitalWrite(11, LOW);
      digitalWrite(10, LOW);
      digitalWrite(9, HIGH);
    }

    delay(1000);
  }
}