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

LiquidCrystal_I2C lcd(0x27,20,4);

#define echoPin 12 // attach pin D12 Arduino to pin Echo of HC-SR04
#define trigPin 13 //attach pin D13 Arduino to pin Trig of HC-SR04

// defines variables
long duration; // variable for the duration of sound wave travel
int distance_cm; // variable for centimeters measurement
const int buzzer = 8;

void setup() {
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an OUTPUT
  pinMode(echoPin, INPUT); // Sets the echoPin as an INPUT
  Serial.begin(9600); // // Serial Communication is starting with 9600 of baudrate speed
  pinMode(buzzer, OUTPUT);
  lcd.backlight();
  lcd.init(); 
}
void loop() {
  // Clears the trigPin condition
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigPin HIGH (ACTIVE) for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  // Calculating the distance
  distance_cm = duration * 0.034 / 2; // Speed of sound wave divided by 2 (go and back)
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance_cm);
  lcd.println(" cm");
  tone(buzzer, 2000);
  delay(100);
  noTone(buzzer);
  delay(distance_cm * 2);
}