#include<reg51.h>
#define lcd P1
sbit rs=P3^6;
sbit e=P3^7;
sbit led=P0^0;
sbit s1=P2^0;
sbit s2=P2^1;
void delay (int);
void cmd (char);
void display (char);
void init (void);
void string (char *);
void view (int);
int count=0;
int no[10]={48,49,50,51,52,53,54,55,56,57};
void delay (int d)
{
unsigned char i=0;
for(;d>0;d--)
{
for(i=250;i>0;i--);
for(i=248;i>0;i--);
}
}
void cmd (char c) //Writing Commands on LCD
{
lcd=c;
rs=0; //Selects command register
e=1; //Enable information on LCD datalines
delay(5);
e=0;
}
void display (char c)
{
lcd=c;
rs=1; //Selects data register
e=1; //Enable information on LCD datalines
delay(5);
e=0;
}
void string (char *p) //Function to display a string
{
while(*p)
{
display(*p++);
}
}
void view (int n)
{
cmd(0xc0); // Force cursor to beginning of second line
//Separates 2-digit number and displays display(no[(n/10)%10]);
display(no[n%10]);
}
void init (void)
{
cmd(0x38); //2 lines and 5x7 Matrix
cmd(0x0c); //Display On, Cursor Off
cmd(0x01); //Clear display screen
cmd(0x80); //Force cursor to beginning of first line
}
void Ext_int_Init()
{
EA = 1;// Enable global interrupt
EX0 = 1; // Enable Ext. interrupt0
IT0 = 1; // Select Ext. interrupt0 on falling edge
}
void External0_ISR() interrupt 0
{
count=0;
string("light off");
led=1;
delay(100);
view(count);
} void main()
{
led=0; //Declaring output pin
init(); //Initializing LCD
Ext_int_Init(); //Initializing Interrupts
string("People in room");
cmd(0xc0); //Forcing cursor to beginning of second line view(count);
while(1)
{
if(s1==1) //IR sensor 1 detects person entering
{
while(s2==0); //Waiting for IR sensor 2 to detect person
count=count+1; //Incrementing counter
while(s2==1); //Waiting for person to fully enter room
view(count); //Displaying updated count
}
else if(s2==1) //IR sensor 2 detects person leaving room
{
while(s1==0); //Waiting for IR sensor 1 to detect person
if(count!=0)
count=count-1; //Decrementing counter
while(s1==1); //Waiting for person to fully leave room
view(count); //Displaying updated count
}
else if(count>=1) //Light turned on if people in room
led=0;
else if(count==0) //Light turned off if no one in room
led=1;
}
}