8051 code of Low Cost path Lightening and Presence Detector

8051-P89V51RD2 */


#include <reg51.h>
#include <string.h>

sbit rs = P2^7;  // declare P2.7 as rs pin
sbit en = P2^5;  // declare p2.5 as enable pin
sbit rw = P2^6;  // declare p2.6 as read/write pin
sbit b = P0^7;   // busy flag
sbit port = P1^2;  // connected to IR sensor
void writecmd(unsigned char a); // function to send command to LCD
void writedat(unsigned char b);  // function to send data to LCD
void busy();   // function to check LCD is busy or not
void writestr(unsigned char *s); // function to write string on LCD

void writecmd(unsigned char a)
{
 busy();   // check for LCD is busy or not
 rs = 0;   // clear rs pin for command
 rw = 0;   // clear rw pin to write
 P0 = a;   // send command character
 en = 1;   // strob LCD
 en = 0;

}
void writedat(unsigned char b)
{
 busy();   // check for LCD is busy or not
 rs = 1;   // set rs pin for data
 rw = 0;   // clear rw pin to write
 P0 = b;   // send data character
 en = 1;   // strob LCD
 en = 0;
}
void busy()
{
 en = 0;   // disable display
 P0 = 0xFF;  // configur P0 as input
 rs = 0;   // clear rs pin for command
 rw = 1;   // set rw pin to read
 while(b==1)
 {
  en=0;   // strob LCD till P0.7 is 1
  en=1;
 }
 en=0;
}
void send(unsigned char d)
{
while(!TI);
TI=0;
SBUF=d;
}
void writestr(unsigned char *s)
{
 unsigned char l,i;
 l = strlen(s);               // get the length of string
 for(i=1;i<=l;i++)
 {
  writedat(*s);              // write every char one by one
  s++; 
 }
}
  
main()
{
    P0=0x00;                      // P0 and P0 as output ports
    P2=0x00;
port=0;
TMOD=0x20;            //Enable Timer 1
    TH1=0XFD;
    SCON=0x50;
    TR1=1;
TI=1;
        writecmd(0x3C);               // initialize LCD
        writecmd(0x0E);   
        writecmd(0x01);

     writecmd(0x01);
send('0');
writestr("Not Occupied");
while(port==0);
 
     writecmd(0x01);
send('1');
writestr("Occupied");
        while(port==1);                       // continuous loop

 }


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