#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
int trig=12;
int echo=11;
int buzzer=9;
int led=4;
int time;
int distance;
void setup() {
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
 
 
 
  // put your setup code here, to run once:

}

void loop() {
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
  time=pulseIn(echo,HIGH);
  Serial.print("travelling time of the wave;");
  Serial.println(time);
  distance=time/2*0.034;
  Serial.print("Distance of the object;");
  Serial.println(distance);
  delay(1000);
  if(distance<300)
  {
    tone(buzzer,1000);
    digitalWrite(led, HIGH);
   lcd.setCursor(2,0);
    lcd.print("**Alert!**");
    lcd.setCursor(0,1);
    lcd.print("Someone is there");
  }
  else{
    noTone(buzzer);
    digitalWrite(led, LOW);
    lcd.clear();
    
  }
  // put your main code here, to run repeatedly:

}