RFID ACCESS CONTROL. SRðAN LALE FACULTY OF ELECTRICAL ENGINEERING EASTERN SARAJEVO

Transcription

1 RFID ACCESS CONTROL SRðAN LALE FACULTY OF ELECTRICAL ENGINEERING EASTERN SARAJEVO 1

2 INTRODUCTION RFID (RADIO - FREQUENCY IDENTIFICATION) systems use RF signals for identification of people, animals and objects. There are two kinds of RFID systems: - active - passive. Passive RFID system consists of three main parts: - reader - transponder - PC or microcontroller. 2

3 RFID SYSTEM STRUCTURE 3

4 RFID READER RFID reader is used for energizing or activation of passive RFID transponder or tag. It consists of control unit and antenna circuit. The antenna circuit produces the carrier RF signal and emits it in the form of electromagnetic waves. The carrier frequency is fixed and determined with antenna resonant circuit parameters. RFID reader is also used for demodulating and decoding of incoming transponder's data. It has possibility of serial RS232 communication with external devices (PC, microcontroller, etc.). 4

5 TRANSPONDER (RFID TAG) Transponder consists of RFID chip and antenna resonant circuit. RFID chip contains an ID information. Antenna receives the electromagnetic waves from reader and transmits them back in modulated form (backscattering proccess). The resonant frequency of the antenna must be the same as carrier frequency of the reader. Transponder performs modulation using stored ID binary data. It is supplied by incoming electromagnetic waves, using standard voltage rectifier. 5

6 OPERATING PRINCIPLES 6

7 EXAMPLES OF RFID SYSTEM IMPLEMENTATION There are many applications with RFID systems: - animal management - marking and recognizing industrial products - book identification in libraries - access control - etc. 7

8 PRACTICAL REALIZATION OF PROJECT Project was realized in the Embedded Systems Laboratory, ETF. The realized RFID access control application consists of following parts: - RFID reader board (mikroelektronika) - printed electronic board with microcontroller PIC 18F4550. RFID cards (mikroelektronika) are used for identification. The application performs control of entry in the office 8

9 PRACTICAL REALIZATION OF PROJECT 9

10 RFID READER BOARD This board is made by mikroelektronika company. 10

11 RFID READER BOARD The main part of the board is EM4095 integrated circuit. The board contains antenna which is suitable for 125kHz frequency. Also, the board has 10-pin connector for easy connection with external devices. In this project, 10-pin connector was connected to microcontroller unit. 11

12 RFID CARDS The used cards are made by mikroelektronika company. 12

13 RFID CARDS RFID card consists of EM4100 chip and antenna. The operating frequency is 125kHz. EM4100 futures 64-bit data memory which is ideal for storing ID information. Every card has unique code which can be identified by RFID reader. There are several options of data rate and coding. The chip has very small size convenient for implantation. Power consumption is very low. 13

14 PRINTED ELECTRONIC BOARD The board contains following components: - +5V power suply - microcontroller PIC 18F4550, with basic connection elements - bipolar transistor for relay activation - 10-pin connector for RFID reader board The board is connected to RFID reader board from one side, and electric lock with relay from other side. 14

15 THE LOOK OF REALIZED RFID SYSTEM 15

16 HOW THIS SYSTEM WORKS? This RFID system was built in near the office door. Person who carries the RFID card puts it above RFID reader board. The reader recognizes the card's unique ID number. Microcontroller PIC 18F4550 sets it's output pin which drives transistor connected to relay. The door with electric lock opens. This is a very simple application, allowing selective entry in the office. The brain of whole system is implemented microcontroller. The programing code of PIC 18F4550 is very simple and it is realized in mikroc program language. 16

17 PROGRAMING CODE OF MICROCONTROLLER PIC 18F4550 The algorithm is quite simple and consists of several steps: 1. The ID numbers (64-bit data) of all tested RFID cards are stored in the microcontroller's memory, in the form of matrix [number of cards][64]. 2. The RFID reader reads the ID number of each card and passes it to MCU. Each ID data is stored in declared series. 3. The read ID number is compared (bit by bit) with stored known ID numbers (from matrix). 4. If every data bit from read card matches with corresponding bit from known card, program sets appropriate output pin, the lock relay activates and person may enter into the office. me RFID reader board should be connected to PORTB. 17

18 DECLARATION OF MATRIX [number of cards][64] char users_number = 2; const char users[2][64]={ {1,1,1,1,1,1,0,1,1,0,0,1,1,0,0,1,0,0,1,0,1,0,0,0,0,0,0,0,0,1,0,0,1,0,0,1, 1,0,1,0,1,1,0,0,0,0,0,0,0,0,1,0,0,1,1,0,1,0,0,1,0,0,0}, {1,1,1,1,1,1,1,1,0,0,0,1,1,0,0,1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,1,1, 1,0,1,0,1,1,0,0,0,0,0,0,0,0,1,0,0,1,1,0,1,0,0,1,0,0,0} 18

19 INTERRUPTS The code uses interrupts to read data sent by EM4095 chip. Clock is read using interrupt on pin RB1. Data is read using interrupt on pin RB0. 19

20 FUNCTION void main() In void main(), after reading ID number and storing it in series data_valid [64], program calls routine int check(). This routine has purpose of checking if read ID number is valid. 20

21 ROUTINE int check() int check() { int exist; for(j=0; j<users_number; j++) { exist=1; for(i=0; i<64; i++) { } if(data_valid[i]!= users[j][i]) { exist=0; } break; 21

22 ROUTINE int check() - continued } } if(exist) { return 1; } return exist; 22

23 RELAY ACTIVATION Instruction if ( check() ) expects the result (variable exist) from check() routine. If the result (exist) is 1, the relay should be activated (the door opens). Otherwise, nothing happens. if(check()) { portd.f2=1; Delay_ms(3000); portd.f2=0; } Delay_ms(3000); 23

24 MCU - RELAY 24

25 CONCLUSION RFID access control has a wide usage. This simple application can be integrated into more complicated systems for identification and surveilance, but the idea of this project was simply to show the basic principles of RFID embedded system used in access control. 25

26 THANKS FOR YOUR ATTENTION! 26