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An RFID Attendance System
Transcript of An RFID Attendance System
Uniquely identifies items
Item orientation to reader not important A general system Hardware Layer IT Layer Tags (transponder)
Antenna Middleware eg. microcontroller
Enterprise application Passive System N. Karmakar, Handbook of Smart Antennas for RFID Systems. Hoboken, New Jersey: John Wiley & Sons, 2010 The reader broadcasts a signal through the antenna creating an EM field called the interrogation zone (IZ).
If a tag is placed within this zone it will reply by sending back its ID. Middleware collects the data from the reader
Enterprise application process the data Passive Tags No onboard power
Recieves energy from the readers EMF
Disposable http://www.libramation.com/ Low Frequency RFID Typically operate at 125 - 134 kHz
Amplitude Shift Keying modulation Antennas are optimised for different frequencies A typical 125 kHz reader has a minimum of 100 turns and a short read range < 14cm Low frequency RFID systems generally operate in unlicesned frequency spectrum http://www.delitosinformaticos.com/ Design & Implementation Hardware RFID Tag 125 kHz RF range
EM4001 ISO based RFID IC
Detection range approximately 7cm
Amplitude Shift Keying modulation
Manchester encoding 64-bit data stream (Header, ID, Data and Parity bits)
4 Billion unique ID's ID-20 RFID Reader 5V
EM 4001 compatible
64-bit manchester encoding
Serial out Microcontroller ATmega328 C Language & C++ Low Cost Multi Platform 14 Digital I/O (6 PWM) pins
6 Analog Input pins
32KB Flash Memory
16 MHz Clock Speed
I2C/TWI Communication Software Reading a Tag Each character is read byte by byte into an array The RFID DB Used to match ID's to names formatted [ID Number],[firstname lastname]
[ID Number],[firstname lastname] Issues SRAM 2KB Reading and writing to SD Card + + + Questions? System Diagram Menu Interface Mark A Roll
Manage Admin Users Select A Class CLASES.TXT Configuration file Class Type Lecture
Exam Date Selection 7 Character class code eg. ECTE458 ID checked agains the database If a mach is found, the students name is displayed on the LCD screen and the name recorded in the roll Only 1 tag can be scanned at once + Reduce the serial buffer to 16 Bytes Roll Stored in directory structure eg. /ECTE458/TUTORIAL/01_11_11.TXT FAT file system limitation Example Use of Data LCD Screen will turn off if no tag is present after 15s Requires an "Admin" card to exit the roll Conclusion Fully functional low cost RFID Attendance System + + Successful Completion