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

LiquidCrystal_I2C lcd(0x27, 16, 2); // Initialize the LCD with I2C address 0x27 and 16x2 display
int trigPin = 2;                    // Pin for the trigger of the ultrasonic sensor
int echoPin = 3;                    // Pin for the echo of the ultrasonic sensor
long duration;                      // Variable to store the duration of pulse
int distance;                       // Variable to store the calculated distance
unsigned long currentTime, previousTime; // Time tracking variables

void setup() {
  lcd.init();           // Initialize the LCD
  lcd.backlight();      // Turn on the LCD backlight
  pinMode(trigPin, OUTPUT);  // Set trigger pin as output
  pinMode(echoPin, INPUT);   // Set echo pin as input
  previousTime = millis();   // Initialize previousTime with the current time

  lcd.setCursor(0, 0);       // Set cursor to the first row, first column
  lcd.print("Welcome to Dist calc"); // Display welcome message
  delay(2000);               // Wait for 2 seconds
  lcd.clear();               // Clear the display
}

void loop() {
  digitalWrite(trigPin, LOW);  // Set trigger pin low for 2 microseconds
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH); // Send a 10-microsecond pulse to the trigger pin
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);  // Set trigger pin low again

  // Read the echo pin and calculate the duration
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance in centimeters
  distance = duration * 0.0343 / 2;

  // Get the current time in seconds
  currentTime = millis() / 1000;

  // Display the distance on the LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance);
  lcd.print(" cm");

  // Display the elapsed time on the LCD
  lcd.setCursor(0, 1);
  lcd.print("Time: ");
  lcd.print(currentTime);
  lcd.print(" sec");

  delay(500); // Wait for 500 milliseconds before repeating the loop
}