| RFID is a new technology advanced by Harry. stockman in his article "Communication by Means of Reflected Power". It generate power for IC operation using RF technology, this revolutionary idea provides great convenience for the operation of IC/ID card. Mifare card is some kind of IC card using RF technology, By far, most cards read appeared can be separated into two kinds, movable and fixed. Fixed cards reader has the advantage of gathering data; it can gather and analyze real-time data easily. But it's not possible to be moved around, and has limitations such as difficult to install and high operation expense. Movable card reader has the advantage of small ground occupation, light weight, high separation efficiency, low cost, but its data needs to be gathered manually. And data can not be analyzed real-timely. Some card reader can transmit data through mobile network. But this kind of card reader has to pay for the operation of mobile network; this is a lot of extra expense. The card reader described in this article uses a wireless transmission module to transmit data automatically to base station in a short range, which can save the expense of manual data gathering and mobile networks.This article designed a p2p wireless protocol, which can provide efficient, reliable data transfer service. When there is no base station around, data will be stored in local Flash memory, when it detected the existence of base station, it will try to connect to the station automatically, pack the data and transfer it to the base station. The design can improve the flexibility of reader and reduce the complexity of data gathering.In this article, hardware design is covered first, system requirements are analyzed, the designing ideas of power module, card operation module, RTC module, wireless module, and CPU module are introduced, and the detailed design of hardware circuit is given. Then the software design is introduced, the paper first analyzes the software design requirements, introduced some wildly-used real-time operating system, carried out the choice of the operating system, and then sub-module described the card reader software design ideas and implementation methods, detailed information on card operations threads and data processes thread are fully presented, and the on-chip Flash module process is detailed described. Then the article explained the thought of bitmap, and used this idea to solve the problem which data can not be erased one by one in flash chip. Afterwards, this article focused on several popular communication protocols, and in accordance with TCP/ IP protocol layering, designed a three-layered short-range high-performance wireless protocol. Next, this paper specifically discusses the data link layer and transport layer protocols of the design, implementation and debugging process. Finally, performance tests are carried out using different parameters of the transmission process, and the best parameters are obtained through experiments. The design of the entire system is based on efficient, reasonable and simple principle; although the system has much to improve either in hardware or software, this automatic data-collection design idea not only provides great convenience, but also provides high efficiency and reliability. This is the innovation point of this paper. |
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