#include <Servo.h>
#include <EEPROM.h>

// Define pins for ultrasonic sensor
const int trigPin = 10;
const int echoPin = 11;

// Define pin for servo
const int servoPin = 9;

// Define variables for distance measurement
long duration;
int distance;

// Create a servo object
Servo myServo;

// Address in EEPROM to store the threshold distance
int thresholdAddress = 0;

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Define the pin modes
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(servoPin, OUTPUT);

  // Attach the servo to the corresponding pin
  myServo.attach(servoPin);

  // Read threshold distance from EEPROM
  int storedThreshold = EEPROM.read(thresholdAddress);
  if (storedThreshold >= 0 && storedThreshold <= 255) {
    Serial.print("Threshold read from EEPROM: ");
    Serial.println(storedThreshold);
  } else {
    Serial.println("Invalid threshold value in EEPROM. Using default value.");
    storedThreshold = 50; // Default threshold value
  }
}

void loop() {
  // Generate a pulse to trigger the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the pulse from the ultrasonic sensor
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters
  distance = duration * 0.034 / 2;

  // Print the distance to the serial monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Check if an object is detected within 50 centimeters
  if (distance < 50) {
    // Rotate the servo to 90 degrees
    myServo.write(180);
    Serial.println("OPEN");

    // Wait for 5 seconds
    delay(5000);

    // Measure the distance again
    duration = pulseIn(echoPin, HIGH);
    distance = duration * 0.034 / 2;

    // Check if the object is still there
    if (distance < 50) {
      // Keep the servo at 180 degrees
      myServo.write(180);
      Serial.println("OPEN");
    } else {
      // Return the servo to the initial position
      myServo.write(0);
      Serial.println("CLOSED");
    }
  } else {
    // Return the servo to the initial position
    myServo.write(0);
    Serial.println("CLOSED");
  }

  // Check if data is available in the serial buffer
  while (Serial.available() > 0) {
    // Read the entered character
    char input = Serial.read();
    // Check if the Enter key is pressed
    if (input == '\n' || input == 's') {
      Serial.println("Serial monitor stopped.");
      return; // Exit the loop and stop further readings
    }
  }

  // Wait for some time before measuring the distance again
  delay(500);
}