#include <LiquidCrystal.h>                             //Using the Arduino as the controller device, the library Allows communication with liquid crystal displays (LCDs).
 LiquidCrystal lcd(13,12,A2,A3,A4,A5);                  // initialize the library by associating any needed LCD interface pin with arduino uno 
 
#define e_s1 3                                          //ultasonic echo pin is connected to pin 2 of Arduino 
#define t_s1 4                                          //ultasonic trigger pin is connected to pin 2 of Arduino 

#define e_s2 10                                         //ultasonic echo pin is connected to pin 2 of Arduino 
#define t_s2 9                                          //ultasonic echo pin is connected to pin 2 of Arduino 

int relay = 12;                                         // relay pin is connected to pin 12 of arduino

long dis_a=0,dis_b=0;                                   //integer dis is created for store the value from ultrasonic sensor
int flag1=0, flag2=0;                                   //integer flag is created to give the value from ultrasonic sensor
int person = 0; 

//function to read untrasonic values 

void ultra_read(int pin_t,int pin_e,long &ultra_time){ 
long time;
pinMode(pin_t,OUTPUT);
pinMode(pin_e,INPUT);
digitalWrite(pin_t,LOW);
delayMicroseconds(2);
digitalWrite(pin_t,HIGH);
delayMicroseconds(10);
time=pulseIn (pin_e,HIGH);
ultra_time =  time / 29 / 2; 
}


void setup(){
  
  Serial.begin(9600);                                     // initialize serial communication at 9600 bits per second:

  pinMode(relay, OUTPUT);                                 // select relay pin as a output pin
  pinMode(13, OUTPUT);                                    // select ultrasonic pin as a output pin
  pinMode(2, OUTPUT);                                     // select ultrasonic pin as a output pin
  pinMode(5, OUTPUT);                                     // select ultrasonic pin as a output pin
  pinMode(8, OUTPUT);                                     // select ultrasonic pin as a output pin
  pinMode(11, OUTPUT);                                    // select ultrasonic pin as a output pin

  lcd.begin(16, 2);
  lcd.setCursor(0,0);
  lcd.print("     Welcome    ");
  Serial.print("hello");
  delay(1000);                                             // Waiting for a while
  lcd.clear(); 
}

void loop(){ 
  digitalWrite(13,HIGH);
  digitalWrite(5,HIGH);
  digitalWrite(2,LOW);
  digitalWrite(8,HIGH);
  digitalWrite(11,LOW);
//*
ultra_read(t_s1,e_s1,dis_a);delay(30);                       //reading the value of 1st-ultrasonic sensor
ultra_read(t_s2,e_s2,dis_b);delay(30);                       //reading the value of 1st-ultrasonic sensor
//*

  Serial.print("da:");
  Serial.println(dis_a);
  Serial.print("db:");
  Serial.println(dis_b);   

if(dis_a<90 && flag1==0){                                      //giving the codition to ultasonic sensor  
  flag1=1;                                                     // intializing flag1 value as 1 
if(flag2==0){                                                  //Applying the condition     
  person = person+1;                                           // adding the number of persons entered in a room 
   }
}

if(dis_b<90 && flag2==0){                                      //giving the codition to ultasonic sensor   
  flag2=1;                                                     // intializing flag2 value as 1
if(flag1==0){                                                  //Applying the condition
  person = person-1;                                           // detecting the number of persons left the room  
  }
}

if(dis_a>90 && dis_b>90 && flag1==1 && flag2==1){              //comparing 1st ultrasonic with 2nd ultrasonic sensor 
  flag1=0, flag2=0;
  delay(1000); 
}


//displaying the values on LCD 
 
  lcd.setCursor(0, 0);                                        
  lcd.print("Have Person: ");
  lcd.print(person);
  lcd.print("  ");
  lcd.setCursor(0,1); 
  lcd.print("Light is ");
  lcd.clear();
   if( person>0 ){
    digitalWrite(relay,LOW); 
    lcd.print("On ");
 }
else{                                                                
  digitalWrite(relay,HIGH );                                      //turn off the relay 
  lcd.print("Off");}
}