Interactive Electronic Whiteboard Circuit Design Based On Ultrasound

With the development of information technology and multimedia technology, teaching methods change a lot, more and more multimedia classrooms have been used in teaching. Especially the slide of the multimedia teaching is the main part, compared with traditional teaching blackboard chalk, slides teaching has a vivid picture, bearing the advantages of large amount of information, lesson plans, portable, clean sanitation, but also lost flexibility in the traditional blackboard teaching, interactive, not easy to modify for knowledge, and tags. The emergence of interactive electronic whiteboard has just overcome this shortcomings.This thesis based on ultrasonic positioning technology designed the hardware circuit part of the interactive electronic whiteboard. This system is mainly composed of launch subsystem and receiving subsystem. Launch subsystem is mainly composed of the controller, ultrasonic signal transmitter, the infrared signal transmitter and some peripheral circuit, ultrasonic signals and infrared emission. Receiving subsystem is mainly composed of main controller, ultrasonic sensors, infrared reception signal receiving sensor and some peripheral components, complete ultrasonic signal receiving, the infrared signal reception work, distance measurement and calculation of coordinates. Launch subsystem is installed a pressure sensitive physical switch, when the ultrasonic signal pen nib (pressure sensitive switch) when performing writing action, press the electronic whiteboard pen will trigger signal launch ultrasonic signals and the infrared signal, the receiving end by installing two ultrasonic receiver respectively measure the distance between the transmitter and the receiver, then according to the positioning algorithm to calculate the signal of the physical coordinates, the coordinates will be uploaded to the computer, through the computer installed on the whiteboard software to complete tag, such as drawing operation. In addition, the design of GPS and GPRS wireless transmission part is joined in this thesis, through the access to remote platform determines the location of the equipment, equipment for remote upgrade and upload the equipment working condition and so on, to facilitate the maintenance of the late; Ultrasonic transmission speed is affected by temperature, temperature measurement module is adopted to improve the compensation; Infrared emission receive part of synchronization for ultrasonic launch time benchmark; SD card storage is used to store the collected signal coordinate values, it’s used for the later analysis measurement error; And dynamic memory SDRAM is used to extend the CPU storage capacity, improve the running speed of the system. Software based on time slice rotation scheduling thought is also embedded in the design of the micro kernel, fully improve the reliability of the system operation and code execution efficiency.The design of this system gives full consideration to the signal of accurate positioning problem, at the same time, it also can real-time monitoring equipment location information and running condition via the Internet, conform to the trend of the development of the intelligent classroom in the future.