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) 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.

Circuit

/*

  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

• /

1. include <18f4520.h>
2. fuses HS,NOLVP,NOWDT,NOPROTECT
3. use delay(clock=40000000) // 40 MHz crystal on PCB
4. 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