this article covers rfid interfacing with at89c51 working at 12Mhz frequency.an rfid module is used for communication, is consisted of a reader and transponder . a transponder or tag communicate with reader through radio waves by receiving and transmitting signal. each tag has unique serial number which is identified by reader.
CODE
code for setting baud rate #9600bps
receive 12 digit number in a variable name 'store' and display the entire string on lcd simultaneously. the last user id(unique number) remains on lcd until the new tag has been introduced
complete code
#include<reg51.h>
#define lcdport P2
sbit rs=P3^1;
sbit rw=P3^2;
sbit en=P3^3;
void receive();
char store[15];
void uart_int()
{
SCON=0x50;
TMOD=0x20;
TH1=-3;
TR1=1;
}
void delay(unsigned int x)
{
unsigned int y;
for(y=0;y<x;y++);
}
void lcdcmd(char A)
{
rw=0;
rs=0;
lcdport=A;
en=1;
delay(500);
en=0;
}
void lcdint()
{
lcdcmd(0x38);
delay(500);
lcdcmd(0x01);
delay(500);
lcdcmd(0x0c);
delay(500);
lcdcmd(0x80);
delay(500);
lcdcmd(0x0e);
delay(500);
}
void lcddata(char a)
{
rs=1;
rw=0;
lcdport=a;
en=1;
delay(500);
en=0;
}
void lcdstring(char *p)
{
while(*p!='\0')
{
lcddata(*p);
delay(2000);
p++;
}
}
void main()
{
uart_int();
lcdint();
while(1)
{
lcdcmd(0x80);
lcdstring("user id:");
delay(200);
lcdcmd(0xc0);
receive();
lcdstring(store);
}
}
void receive()
{
int k;
for(k=0;k<12;k++)
{
while(RI==0);
store[k]=SBUF;
RI=0;
}
}
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