Software System Design Of A Visibility Meter

This project aims to develop a system which helps teachers to check and keep arecord of students’ attendance. A lot of references are read, a survey of user demands isconducted and analyzed, and systematic design and testing methods are adopted tocomplete this project. The principle and key difficulty of the RFID technology areanalyzed. Several encoding algorithems are also studied, and a type of125kHz lowfrequency RFID tag is adopted, based on which a low-cost RFID tag reader with highperformace is implemented. Moreover, an attendance checking system is developedbased on RFID according to proper principles of software development, informationsystem management. High performance but with low cost is the advantage of the RFIDtag reader, while the attendane checking system as a software is outstanding for itseasy-to-do managing capability.The entire RFID attendance checking system consists of three subsystems (ormodules): RFID tag reader, wireless/serial communication module, the attendancechecking software. The RFID tag reader will access the identification information of theRFID tag and send it to the attendance checking software on the Upper Computer,which keeps an attendance record, via the wireless/serial communication module. Thesystem integrates a series of functions from RFID tag reading, data transmitting,attendance checking and statistics processing, which improves the current attendancechecking method, and thus improves the attendance checking efficiency.Part of the system hardware work includes: MCU control circuit design, modulatorand demodulator-RF front-end circuit design for the RFID card reader, NRF24L01wireless communication module design, the USB-UART serial communication moduledesign based on PL2303.The system software consists of to parts: Embedded Software (lower-side machine)and PC-side software (upper-side machine), which also includes embedded software fotthe EM4100card reader with Manchester code decoding process design, NRF24L01wireless communication program design, UART serial communication program design,system status indicator program design, communications, data flow and packet processing; PC-side software, including establishment of a database with ACCESS,database SQL language operation based on Visual C++, USB-UART serialcommunication program with data stream processing, data compression anddecompression with LZW algorithm, user interface design and message response designand so on.The thesis is organized as follows: Chapter I Introduction, this article introducesthe research background, the main research content, research objectives and significanceof research ideas and methods; Chapter II explained from the aspects of thedevelopment process and application trendsthe RFID technology and its basic theory;Chapter each of the various modules of the time and attendance system hardware circuitdesign detail; Chapter IV describes the time and attendance system software designcomes to the basics and theory;chapter elaborates the design details of the attendancesystem software, including the reader embedded software design, the PC client softwarerequirements analysis, the system PC client software design, database design,system-related processes elaborated with algorithms,which contains the EM4100thereader embedded software design and the Manchester decoding procedures the design,NRF24L01program designed UART serial communication program design, data packetformat and communications protocol development, and explicitly defined; Chapter VIinto the time and attendance systeminstallation and commissioning; Finally, Chapter VIIof the full text contents of the review and sum up, the prospects for the development ofRFID technology outlook.