Infrared Touch Screen Design Based On ARM Cortex-M3

Infrared touch screen is an absolute coordinate positioning system withcombination of LCD monitor or projector, and to provide users with a simple, directand natural way of human-computer interaction. Infrared touch screen technology is abranch of touch technology, and it has been praised by the industry due to theadvantage of high light transmittance, high positioning accuracy and no drift, and theinfrared touch screen applications become more and more widely. The data of thetouch market shows: infrared touch technology accounted for the proportion ofinteractive electronic whiteboard touch solution will increase year by year. Theinteractive electronic whiteboard is applied to the education industry, it can replacethe traditional blackboard with dust-free writing and freely touching, with the rapiddevelopment of materials science and technology, electronic whiteboard’s size willbecome larger, so this paper puts forward a kind of infrared touch screen design forinteractive electronic whiteboard.According to basic principle of infrared touch screen, This paper developmentthe research between transmission power and the distance of infrared transmittingtubes and the later firmware of the touch products updates at real time, It mainlysolves the infrared tube’s launch distance did not meet the requirements of infraredtouch screen size, making the use of infrared touch screen’s uniaxial localizationalgorithm is to implement the corresponding touch function as well as to guaranteeafter-sales service.This paper adopts ARM Cortex M3STM32F103as a processing core of infraredtouch device, STM32F103takes advantage of its I/O interface to output a certainwidth of the pulse signal, and combining with the shift register74hc595, it can lightup any position of the infrared transmitting tube, then the STM32open thecorresponding infrared receiving tube to receive infrared signal, after the infraredsignal is dealt with the signal conditioning circuit and is sampled by the embeddedADC of MCU, and the analog signal will become into digital signal, and it will get thecoordinates of the touch point’s current position through the corresponding algorithm.the MCU will finally transfer the coordinate information and command information toPC via its built-in USB control unit, PC makes the corresponding response operationafter receiving information.The Hardware’s feature of this paper is the control circuit of the infraredtransmitting tube, infrared transmitting tube by group is processed in order to simplifythe external pressure of the software design, so STM32F103can have more time to beresponsible for the algorithm. Hardware circuit system that is based on the basicprinciple of infrared touch screen is improved and only the X axis direction collocateone-to-one infrared tube circuit, to verify single axis positioning algorithm and theupdate algorithm online of infrared touch HID devices. To respect basic mathematicaltheory, it improves algorithm through experimental data, in order to the real suitable for the actual situation.