#include <LiquidCrystal.h>

// Initialize the LCD with the interface pins
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

// Define pins for the Ultrasonic Sensor
const int trigPin = 9;
const int echoPin = 10;

void setup() {
  // Set up the LCD's number of columns and rows
  lcd.begin(16, 2);
  lcd.print("Distance:");

  // Set up the ultrasonic sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  // Clear the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigPin HIGH for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echoPin, returns the sound wave travel time in microseconds
  long duration = pulseIn(echoPin, HIGH);

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

  // Clear the previous distance from the LCD
  lcd.setCursor(0, 1);
  lcd.print("                ");
  
  // Set the cursor to the second row, first column
  lcd.setCursor(0, 1);
  // Print the distance on the LCD
  lcd.print(distance);
  lcd.print(" cm");

  // Wait before the next reading
  delay(500);
}