Reading RFID tags

Original Assignment

Interface your PIC with an RFID reader (see here) and demonstrate recognition of various RFID tags.

Overview

Radio Frequency Identification (RFID)is a generic term used to describe technology that uses radio waves identify objects. The Parallax RFID Card Reader, Serial (#28140) reads passive RFID transponder tags up to 4 inches away from the reader. The RFID communicates using rs232 and transmits a 12-byte ASCII string. The first byte (start byte) is always $0A and the last byte (stop byte) is always $0D. The 10 middle digits are the 10 unique id digits that are unique to every RFID transponder.

Code

/*
   RFID_Input.c J.Cooper and C.Ryan 2009-2-04
   Read in from RFID Card on pin RC7
   Write out RFID unique number on pin RC6
*/
#include <18f4520.h>
#fuses HS,NOLVP,NOWDT,NOPROTECT        
#use delay(clock=40000000)         // 40 MHz crystal on PCB
#use rs232(baud=2400, UART1)      // hardware UART; uses  RC6/TX and RC7/RX

int16 i;
char value[12];//12 values of tag ID

output_low(PIN_D7); //Set enable to low

void main() {
     for (i=0; i<12; i++) { //read in the 12 values
           value[i]=getc();
     }
     printf("rfid# %c %c %c %c %c %c %c %c %c %c \r\n", value[1] value[2] value[3] value[4] value[5] value[6] value[7] value[8] value[9] value[10]); //display 10 unique id digits
}

Further Reading

Product Website

Data Sheet