#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define TRIG_PIN 3
#define ECHO_PIN 2
#define BUZZER_PIN 9

long duration;
int distance;

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  Serial.begin(9600);
  lcd.begin();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
}

void loop() {
  // Trigger ultrasonic sensor
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Read echo and calculate distance
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.0344 / 2;

  // Print to Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Display distance on LCD first row
  lcd.setCursor(0, 0);
  lcd.print("Distance:       "); // Clear old value
  lcd.setCursor(10, 0);
  lcd.print(distance);
  lcd.print("cm");

  // Check for object detection and update second row
  lcd.setCursor(0, 1);
  lcd.print("                "); // Clear second row
  lcd.setCursor(0, 1);
  if (distance < 10) {
    lcd.print("Object Detected!");
    tone(BUZZER_PIN, 1000);
  } else {
    lcd.print("No Object       ");
    noTone(BUZZER_PIN);
  }

  delay(500);
}