Design Of Electronic Whiteboard System With Resistive Touch-screen

With the great improvement in computer technology and microelectronics, alarge number of traditional mechanical devices like relays and buttons is graduallyreplaced by the touch screen technology,which becomes a widespreadhuman-computer interaction and control equipment. Touch screen owns the featuresof portable and easy to operate, which is an irreplaceable advantage of a traditionalkeyboard.For whiteboard to low-cost, high-resolution, anti-jamming, goodsynchronization trend display development, the paper according to the workingprinciple of the resistive screen and the specific relationship between resistance andcoordinates the design of resistive whiteboard system. The purpose is to achieve thefunction in which things written or drew on the resistive touch screen acting as theinput device, through the resistive screen controller chip ADS7846and themicrocontroller MSP430as the core controller receiving、processing and sending datacan be displayed on the user-friendly MATLAB GUI interface. Resistive whiteboardinexpensive, high stability, high definition, long service life. Resistive whiteboardapplications, will greatly reduce the price of whiteboard products, improve productcost.In this paper, the main content includes the design and development of electronicwhiteboard system with resistive touch-screen,calibration of resistive screen, analysisof instrument test results.1. Development of resistance whiteboard system. By comparing the variousexisting whiteboard technology are introduced and performance, as well as highprices for whiteboard operating limitations proposed resistive whiteboard overalldesign. According to the overall design, hardware and software were designed,fabricated resistive whiteboard devices.2. Resistive screen calibration. In practice, taking into account the error resistivetouchscreen own performance and installation methods produced, usually makes zero coordinate resistance touch screen is not a valid range, and therefore the coordinateappearing on the LCD screen by touch in contact with the actual coordinates from acertain bias. Resistive touch screen needs to be calibrated before use to ensure thatreduce this bias. This paper uses a four-point calibration method.3. The instrument of analysis of test results. Through analysis of the results of thetest equipment to prove the feasibility of the design. Then the test results analysis, thebasic parameters and the error range of the device. Summarizes several factors whatmay lead to errors, and propose appropriate solutions.Content can be seen from the above work that the key technology of this designis that a particular relationship to the resistance and coordinates as the basis formeasuring the resistance value of the contact with the resistive screen. After A/Dconversion,it give the microcontroller from a numeric parameter to coordinateconversion, and then sent to the computer via Bluetooth coordinates, PC receivescoordinate information on the microcontroller via PC interface mapping coordinateinformation. Then through the microcontroller programmed resistive screen controller,Microcontroller and PC communication program design and PC software programdesigned to achieve rapid, accurate, continuous and good synchronization displaysystem.