Research And Development Of Industry-Specific Touch Screen

With the advancement of science and technology and the development of industrialization,on the industrial machine with human-computer interaction function,the touch screen device has replaced the buttons and indicator lights in the traditional control system,and has been widely used.In order to meet the needs of industrial rapid application,it is necessary to design a dedicated touch screen system that can be applied to various industrial machines.The users can gain convenience when using the touch screen system and the accompanying programs for man-machine interface design and industrial-specific graphic design.This article first introduces the development of human-machine interaction and touch screen technology at home and abroad.It also describes the research background and research significance of the dedicated touch screen system,and proposes relevant design schemes and research contents.The main research work is as follows:1)By analyzing the application requirements of the human-computer interaction interface design of embedded systems and industrial machines,the overall scheme of the industry-specific touch screen system is proposed.The system is based on STM32F407 as the main chip,through the configuration of the FSMC analog 8080 interface,in order to drive the TFT resistive screen,whose controller is RA8875.2)The CAN bus interface was designed as the communication interface between the control system composed of MCU and touch screen and the industrial machine.The SN65HVD230 chip was used as the CAN bus transceiver.3)According to the hardware design scheme,the hardware circuit of the industry-specific touch screen system is designed,which mainly includes the hardware circuit schematic design of the five basic modules such as the minimum required single-chip microcomputer system,touch screen,communication interface,network interface and the interface between the single-chip microcomputer and the touch screen.In addition,a hardware circuit for automatically recognizing the resolution of the touch screen is used to meet switching requirements of screens with different resolutions.The hardware circuit realizes improvement depending on the 4*5 dot matrix keyboard interface provided by the RA8875,and can achieve up to 20 kinds.Different resolution of automatic recognition,and does not take the microcontroller input and output port resources.4)According to the software design scheme,design the software of the industry-specific touch screen system.It mainly includes system initialization program design(including resolution automatic recognition program and horizontal/vertical screen display setting program),common plane geometry parametric display function program design and state machine realization interface switching program design.At the same time,two common menus,drop-down menu bar and window menu bar,are designed to be used for the programming of human-computer interaction interface designers.5)Compress the graphics library with variable length compression(VLC)algorithm.When creating a graphics library,some industrially complex graphics that are not easily spliced using basic plane geometry are first drawn by the computer graphics software into bitmaps in BMP format,and then bitmaps are generated by IMAGE2 LCD graphics data production software.The left-to-right and top-down scan mode outputs the C-language array data in the RGB565 format.Finally,it is burned and stored in the external serial flash memory.In order to optimize the system and save FLASH storage space,the graphics library can save more picture information,so the variable-length compression algorithm is used to compress the graphics library.6)The touch screen system is tested,and the four aspects of power supply,reset circuit,touch screen read/write signal and automatic recognition of the touch screen resolution function are performed,and the test results meet the expected design requirements.