#include <Servo.h>

// Pin definitions
const int trigPin = 5;
const int echoPin = 4;
const int buzzerPin = 12;
const int servoPin = 6;

// Ultrasonic variables
long duration;
int distance;

// Servo variables
Servo myservo;
int pos = 0;        // Current servo position
int direction = 1;  // 1 for increasing, -1 for decreasing

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  myservo.attach(servoPin);
  myservo.write(pos);  // Initialize servo position
}

void loop() {
  // Move servo
  pos += direction;
  myservo.write(pos);
  
  // Change direction when reaching limits
  if (pos >= 180 || pos <= 0) {
    direction *= -1;
  }

  // Measure distance
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

  // Control buzzer based on distance
  if (distance < 25 && distance > 0) {
    digitalWrite(buzzerPin, HIGH);
  } else {
    digitalWrite(buzzerPin, LOW);
  }

  // Delay for smooth servo movement and sensor stability
  delay(15);
}