RFID Tag Reader SystemKatonio Butler and Akua Nti6.111: Introductory Digital Systems LaboratoryDecember 14, 2005AbstractRadio Frequency Identification (RFID) technology holds much promise as applied to areassuch as remote sensing and access control. The RFID reader system constructed in this projectwas des igned to demonstrate access control through the use of low-frequency ID cards. Thesecards contained identification data that is read by the reader, sent to a database where it iscompared to stored values, and implemented depending upon the level of access associated withit. If the c ard’s identification data is in the system, a stored image as well as the name of theuser associated with the ID card is displayed. If the data is not in the system, it notifies theuser with the me ss age “ACCESS DENIED!” on a display screen. The reader was successfullyconstructed using Ve rilog hardware description language in an FPGA.1Contents1 Introduction 42 RFID Tag Reader System Overview 43 Tag Reader System Module Descriptions 53.1 RFID Reader Chip (Akua) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2 Asynchronous Receiver (Akua) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.3 Database (Akua) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.4 Display (Katonio) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.4.1 VGA ROM Display (Katonio) . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.4.2 VGA Synchronizer (Katonio) . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.4.3 Character Display (Katonio) . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Design and Testing 94.1 Design Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.2 Testing and Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Conclusions 11A Verilog Code 12A.1 Top-Level RFID Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13A.2 Asynchronous Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21A.3 Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26A.4 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B Miscellaneous 37B.1 PGM-to-COE Conversion Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37B.2 Card Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391List of Figures1 RFID Tag Reader System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . 62List of Tables1 Card ID Number Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Card ID Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3931 IntroductionRadio Frequency Identification (RFID) is a remote sensing and contol technology that can be usedto identify and track people or objects. Applications of the technology include logistics, inventorymanagement access control.An RFID system typically consists of a tag, or transponder, and a reader. The RFID tagcontains a digital memory chip with a unique ID, and an antenna to send data to and receive datafrom a reader. The RFID tag reader consists of a transceiver and decoder. The reader transmits acontinuous interrogation signal which is rece ived by a tag when it is within range. Upon receivingand decoding this signal, the tag sends the reader its identification data, which is typically a streamof bits.When the reader receives proper identification data from the card, it can then send commandsignals to the tag. Res ponding to comm ands from the reader, the tag sends out encoded data. Thisdata, which is sent out on an amplitude-modulated frequency, is received and decoded by thereader. The reader then sends it to a host computer to be processed.Our RFID tag reader system combines a tag reader module with a VGA display to demon-strate the use of RFID for access control. It displays messages and images that depend on the IDnumber of the card and the level of access associated with that number.2 RFID Tag Reader System OverviewA principal application of the RFID tag reader system is access control. Only people with cardswhose ID numbers are in the database can unlock a door or have some other ac ce ss to a facility.Additionally, if the system is used at a place where a human is checking identification, the guardcan make sure the person holding the card is the person associated with the card by viewing thepicture.Typical use of the tag reader system is as follows: A user holds up a card in front of thereceiver, parallel to the antenna. The value on the card is compared to values in a database,and a picture is displayed based on the card’s level of access. If the ID is in the database, thecorresponding picture and name is displayed on …
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