#include <LiquidCrystal.h>

// Define pins for the ultrasonic sensor
#define TRIG_PIN 12
#define ECHO_PIN 14

// Define pins for the LCD
#define RS 4
#define EN 5
#define D4 18
#define D5 19
#define D6 20
#define D7 21

// Define pin for the buzzer
#define BUZZER_PIN 13

LiquidCrystal lcd(RS, EN, D4, D5, D6, D7);

void setup() {
  // Initialize the LCD
  lcd.begin(16, 2);
  
  // Initialize the ultrasonic sensor pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  
  // Initialize the buzzer pin
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);
  
  
  lcd.print("Distance: ");
}

void loop() {
  // Send a 10us pulse to trigger the ultrasonic sensor
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  // Measure the duration of the echo pulse
  long duration = pulseIn(ECHO_PIN, HIGH);
  
  // Calculate the distance in cm
  float distance = duration * 0.034 / 2;
  
  // Print the distance on the LCD
  lcd.setCursor(0, 1);
  lcd.print("            "); // Clear previous distance
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm");
  
  if (distance <12) {
    tone(BUZZER_PIN, 100);
  } else{
    noTone(BUZZER_PIN);
  }
  
  delay(500); // Wait before taking another reading
}