Design Of Complete Synchronization Digital Frequency Meter Based On FPGA

To meet the needs of the information age, ensuring security of the internal architecture and the users different kinds of needs , entrance guard system comes out Gathered with computer technology, electronic technology, mechanical technology, magnetic-electric technology and radio frequency identification technology, Access Control System makes card and locks get " integrity dialogue" function. That smart cards to control the open or close of the doors ,introduces a new management concept , which not only manager can provide a safe, faster, more automated management style, but also offer the users, a great convenience. In this paper, we research on the design of radio frequency identification Access Control System.(1) This paper introduces the design of the Access Control network system based on radio frequency identification IC card, which analysises the design of hardware detailedly, gives out the electric circuit principle diagram of making contactless IC card Proximity Coupling Device(PCD). The PCD is consisted of RF antenna, read/write module, RS485 communication interface and MCU, which can read/write the Mifare contactless Smart Card of Philips company, the distance of reading card is 10 cm roughly.The system will display the clock when there is no card entered into the scope of RF energy; when the card entered into that, the reading card data will be displayed.(2) Deeply studed the RFID antenna EMC filters, receive circuit and antenna matching circuits, etc., and considering the special design,we use the coil antenna ,optimize the coupling circuit by raise the quality factor Q and the frequency tuning.(3) Regard the Application for network equipment requirements ,Access Control Terminal using RS485 communications, while combining Access Control RS485 reader on the network topology, through the RS485 interface and PC component communication network system. Reader peacetime can work independently, PC every opportunity to visit some time reader, with PC clock reunification on the clock calibration reader, and the memory card reader to read data to the reader to obtain timely data processing.(4) The Design including watchdogs, LCD, data storage and real-time clock module, and other peripheral circuits, using serial design such as SPI, I2C, thus saving the MCU's I / O interface. Access Control System Design at the same time combining the access control circuit, completed the equipment selection.(5) To meet the Radio Frequency Identification Access Control System design requirements ,we design by modular software method. According to the characteristics of MF RC500 and the systematic research on the operation of MF RC500 chip process, design the flow chart of the main program modules subroutine, use C51-language development the bottom of the reader control software, and completed the debugging process that results meet the design requirements.RFID with convenient and efficient becomes the focus of attention of the industry, and China is being an RFID tag production of the most promising production base.Applicated Radio frequency identification to the Access Control System, has broad application prospects. Based on this thinking, this paper gives out the realization of the specific design, but also to be further study on the expansion, such as the use of Internet access to replace RS485 interconnection, expanding the size of the system.