The Access Control System Based On RFID And CAN Bus

As a precautionary measure of protecting internal security of buildings and preventing illegal invasion, accesscontrol security systems have attracted more and more attention in modern life. With the continuous development ofrelated technologies, the access control system, which was small-scale, mechanized and contactless in the early days,has gradually developed into the intelligentized, information-based and integrated control system. The coretechnologies which can reflect the identification of modern intelligent access control systems mainly refer to theautomatic identification technology and network communication technology. Without any human intervention,automatic identification technology firstly passes the identified target data to the reader device, and then completing theprocess of identification and exchange about information. As a key part of the information transmission network,communication technology can transmit the information between the front-end equipment and the background set.The first started with the introduction of the application background, current development, composition andfunctions of this system, then analysed the principle of CAN bus technology and RFID automatic identificationtechnology, especially those about working principle and the transitive method of the reader and responder of RFID.The algorithm of RFID anti-collision was also explained and improved. Finally by comparison, the system programwas planned.The structure of the system included CAN bus communication module, control module, RFID reader module. Onthe basis of the analysis about these former components, the software system was developed. Analysis about hardwareof each module was mainly about the hardware pin descriptions and device characteristics of CAN controller MCP2515,CAN transceiver TJA1050, processor Atmega16, and the RFID reader MFRC522. In this procedure, the connectionmethod of interface circuit about corresponding module and the design of antenna were given emphatically. As for thesoftware, C language was chosen as the programming language because of its good versatility and portability. With theuse of it, modular program design was presented. At the same time, the communication processes of MFRC522chipand RFID, along with MCP2515which was the bus controller of CAN were systematically studied. And SPI serialcommunication was simulated by software. Finally, according to the related flow charts, subroutine of each module isdesigned.Based on the above research work, RFID reader module implemented the operation of RFID about searching, anti-collision, election, and reading and writing cards. The collected information of cards has been successfully transmittedto the background PC by the CAN bus, thus completing the major controlling step of intelligent access control system.