#include <Servo.h>

const int trigPin = 9;
const int echoPin = 10;
const int ledMerah = 12;
const int ledHijau = 11;
const int servoPin = 6;

Servo myServo;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledMerah, OUTPUT);
  pinMode(ledHijau, OUTPUT);
  
  myServo.attach(servoPin);
  myServo.write(0);  // Servo starts at the initial position (0 degrees)
  
  Serial.begin(9600);
}

void loop() {
  long duration, distance;
  
  // Send ultrasonic pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Read echo time
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate distance in cm
  distance = duration * 0.034 / 2;
  
  // Display distance on Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  // Control LED and servo based on distance
  if (distance > 0 && distance < 100) {  // Check for a valid reading (distance > 0)
    digitalWrite(ledMerah, HIGH);
    digitalWrite(ledHijau, LOW);
    myServo.write(0);  // Move servo to 0 degrees if distance is less than 100 cm
  } else {
    digitalWrite(ledMerah, LOW);
    digitalWrite(ledHijau, HIGH);
    myServo.write(90);  // Servo moves to 90 degrees if distance is greater than or equal to 100 cm
  }
  
  delay(500);  // Wait 500ms before re-measuring
}