#include <Wire.h>
#include<LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0X27,16,2); 
const int trigger = 9; 
const int echo = 7; 
const int buzzer = 11; 
const int led = 12; 
void setup() 
{
   pinMode(trigger, OUTPUT); 
   pinMode(echo, INPUT); 
   pinMode(buzzer, OUTPUT); 
   pinMode(led, OUTPUT); 
   Serial.begin(9600); 
   lcd.init(); 
   lcd.backlight();
}
void loop() 
{
  digitalWrite(trigger,LOW); 
  delayMicroseconds(5); 
  digitalWrite(trigger, HIGH); 
  delayMicroseconds(13); 
  digitalWrite(trigger, LOW); 
  long duration = pulseIn(echo,HIGH);
  long distance = (duration * 0.0343) /2;  
  Serial.print("Sensor distance :");  
  Serial.println(distance);  
  if (distance < 75)  
  tone(buzzer , 100);  
  else 
   noTone(buzzer);  
   if (distance > 75)  
   digitalWrite(led , LOW);  
   else  
   digitalWrite(led , HIGH); 
    lcd.setCursor(0,0);  
    lcd.print( "Distance ");  
    lcd.setCursor(0,1);  
    lcd.print(distance);
    delay(500);
}