Design And Implementation RFID Reader In Vehicle License Plate Identification System

By the rapid development of Chinese economic and the continuous progress of science, the number of private car rise continually, at the same time, car-stealing, carjacking, plate-stealing, vehicle license plate misappropriation, hit-and-run accident, vehicle-smuggling happen more often. In fact, it has become a hot issues that how to improve the intelligent management of vehicle. The approach of vehicle identification as a core of the vehicle management has drawn more and more attention. The leading role of vehicle license plate which is the unique external sign of Motor vehicle registration is reflected in its visibility and uniqueness. The traditional vehicle identification approach is based on image, which will be interfered by the distance, angle, pollution, light and other factors , also can not resolve the recognition problem caused by car plate misappropriation and the card theft ect. Therefore, the subject of this paper makes use of the remote radio frequency identification technology, namely, embedding RFID chips in the vehicle without changing the appearance of the original vehicle license plate, which can not only achieve the long-range vehicle identification, but also get rid of the influence of angle, light extrinsic factors. It has referential significance to crack down illegal and criminal activities and achieve effective, rapid vehicle management.The first chapter of this paper outlines the domestic and international development of radio frequency identification technology briefly combining the practical problems of the project, discusses the significance and the necessity of design and implementation of ultra-high frequency for reading and writing, at last, illustrates the major work of this study.Chapter II describes the design of RFID Reader. It expounds the steps of the system overall design, formulate the design method, namely, first whole design then parts design. This chapter makes a detailed analysis of the working process and the functions of the RFID Reader, then gets the following specific needs in five aspects: the communication distance between the Reader and transponder, the communication distance between the Reader and host computer, the method of the Reader and host computer communication, data transmission integrity, RFID Reader meeting the standards. On the basis of the demand analysis, this paper establishes a Reader architecture, which use the ARM microprocessor architecture as the hardware development platform and embedded operating system as the software development platform. Based on this architecture, we use modular design method to complete the design of the Reader system hardware, software architecture. In hardware architecture design, considering all the factors, by taking into account the complexity of the reality and the cost concerning mass production, the chip option of each module are completed. As the RFID Reader, to read and write module is the priority of the development section, to choose the right radio frequency Reader module is helpful to meet the system's functional requirements, so this paper will take the functionality and interface of radio frequency Reader module as the benchmark of the Reader hardware development and design. Furthermore, embedded Linux, as a multi-task, stable and reliable operating system kernel which can be cut is an excellent software platform for developing embedded products. Therefore, in the design of the software architecture, taking into account the maturity of the operating system and real-time, this paper chooses embedded Linux as the operation of the Reader.The third chapter designs a complete Reader hardware circuitry based on the overall design of the hardware architecture. The circuit system is based on Reader hardware functions to be achieved by using a modular approach design, such a design makes for easily finding the fault when Reader goes wrong, also replacing damaged modules, therefore it can avoid the circumstance that problems in one part cause the entire system to work improperly. Based on the effect of the Reader in the whole RFID Reader system, the role of the hardware part of the Reader is divided into four modules: embedded processor modules, modules read and write capabilities, communication modules, and power supply module. Embedded processor module, includes storage systems, reset circuit, clock circuit, and other testing and accessibility interface, mainly achieves to process Reader-related data and controls exchange of data in modules; power supply module mainly achieve the conversion in different voltage and provide a stable power supply for modules of the Reader; RF function modules mainly achieves accesses the data of passive transponder, and send data collected to the department module through the UART interface, communication modules, includes Bluetooth communication, network communication and serial communication, mainly achieved the data communication between the main processor module and the host computer ,and network communication is achieved by Ethernet controllers.Chapter IV introduces the Reader embedded application software design structure and details of the implementation process. First, according to the Reader hardware design previous chapter it takes embedded Linux operating system, as Reader application operating system of the development platform. Secondly, based on an embedded Linux operating system structure, the Reader application program is divided into two parts, one for the system software, which is implemented in the embedded Linux kernel Reader serial I/O device drivers and Ethernet equipment DM9000 device driver, configurable embedded Linux operating system kernel. The other part of the upper for the embedded Linux operating system, application software design, that is, to adopt multi-threaded programming techniques, according to Reader to achieve the functions of these functions which will be divided into modules for each functional module the task of creating one or more threads, and then create a thread to handle thread scheduling tasks of these function blocks threads. It uses embedded Linux multi-threaded programming techniques in the message queue to control the communication between multiple threads; in order to control the same process multiple threads on the same shared memory address access, it uses embedded Linux multi-threaded programming techniques in the semaphore, mutual exclusion of locks, etc. to achieve the multi-threaded synchronization and mutual exclusion between. Again, to pars WJM3000 communication protocol and the Bluetooth module control commands, to formulate a consistent Reader and host computer communication standard mechanism. Finally, this paper builds data structures for multi-threaded program for Reader, and elaborates the concrete realization process of threads. In this chapter the realization of multi-threaded communication between not only used when the message queue control thread execution, but also to create a processing thread of the thread, that is, message processing thread, which is the realization of multi-threaded program, the key thread scheduling. Message Queuing used in this chapter does not take into account the priority of the queue, if you want a more perfect realization of the communication modules for each task, you might consider with a priority of the thread and message queues, intermediate structures can be designed to thread scheduling algorithm to achieve according to priority scheduling worker thread.The fifth chapter describes the testing process on the Reader system. This chapter, we use the Reader and the host computer, gain antenna to build test platform, through which we can undertake the reading, writing, and a series of operations for passive transponder to test the feasibility of the design of Reader. Through the Reader and the host computer on-line testing, we understand working principle and transport mechanism of RFID, verify the accuracy when Reader executes and transfers commands in real time. Chapter VI summarizes the work in this paper, indicates the part which needs to be improved in the system, and makes outlook of the design of the safety on UHF band radio frequency identification technology in next step. This design has achieved the identification, reading/writing and other functions for transponder, the desired objective has been met.