Tut 14 : RFID

RFID (Radio-Frequency IDentification) is a small electronic devices that consist of a small chip and an antenna. The chip typically is capable of carrying 2K/4K/8K bytes of data or less. The RFID device serves the same purpose as a bar code or a magnetic strip on the back of a credit card or ATM card since it provides a unique identifier for that object. 

The RFID device must be scanned to retrieve the identifying information from the cards or tags. A significant advantage of RFID devices over the others mentioned above is that the RFID device does not need to be positioned precisely relative to the scanner. 

In contrast, RFID devices will work within a few feet (up to 20 feet for high-frequency devices) of the scanner. Some short distance RFID works below than 10 cm. Some common problems with RFID are reader collision and tag collision. Reader collision occurs when the signals from two or more readers overlap. The tag is unable to respond to simultaneous queries.Systems must be carefully set up to avoid this problem. Tag collision occurs when many tags are present in a small area. But since the read time is very fast, it is easier for vendors to develop systems that ensure that tags respond one at a time.

 

RFID tags may be used as:

• Animal tracking tags, inserted beneath the skin.
• Tags can be screw-shaped to identify items, trees or wooden items.
• Credit-card shaped for use in access applications.
• Smart attendance and parking system.

 

 RFID reader and tag(transponder)

 

System block diagram

Application of RFID in parking system

 

PBP Program

'program to use RFID reader and tag 

 

DEFINE OSC 20

   @ device hs_osc                         

INCLUDE "modedefs.bas"          ' Include serial modes

DEFINE HSER_RCSTA 90h           ' Definition serial modes utk Hserin

DEFINE HSER_TXSTA 24h

DEFINE HSER_BAUD 57600             ' 57600 Bauds rate

DEFINE HSER_SPBRG 21

DEFINE HSER_CLROERR 1

 

buf VAR BYTE(7) 

' -----[ EEPROM Data ]-----------------------------------------------------

Tag1 Data "AES8915"         ' ID 1

Tag2 Data "PGL9796"          ' ID 2

Tag3 Data "PJT4769"           ' ID 3

Tag4 Data "NAV8915"          ' ID 4

Tag5 Data "BFE6529"          ' ID 5

Tag6 Data "FE6529 "            ' ID 6

Tag7 Data "*BFE652"          ' ID 7

 

loop:

HSerin [WAIT("*"),STR buf\7]    

Check_List:

'checking commands  

Goto loop