Touch screen is a simple, convenient and natural multimedia interactive device.Direct input operations have become popular worldwide.Android mobile devices (smart phones, tablet computers, etc.) choose a full-touch screen as their main input mode due to the need of input operation. In order to achieve multi-touch, almost all of them use capacitive touch screen.The realization of touch screen is very beneficial to the expansion of screen function, so the application scope is greatly expanded.The larger screen size opens up a wider market space for touch screen, and also puts forward higher requirements.How to ensure the stability of the touch screen system, how to improve the overall performance of the system, how to enhance the user experience, is the focus of this paper.
A.The touch screen is designed as zone A and zone B, zone A is used to detect the coordinates of touch points, and zone B is used to detect touch gestures. Besides, the user experience is improved through the reasonable setting of some relevant parameters in zone B.
2.On the basis of careful study of Android system architecture and mobile phone hardware structure, SPI bus touch screen system hardware design is completed.
3.Designed the data transmission mode and protocol of touch screen control IC, wrote the touch screen driver integrated into the system kernel, made the data of touch screen control IC quickly and accurately transmitted to the operating system through SPI bus, and successfully realized the interaction between the operating system and the touch screen hardware;
Four.Deeply studied the Android Linux Kernel, especially the input subsystem, SPI subsystem, work queue mechanism and other modules;
Five.After the Android version was upgraded to 2.2, the touch screen multi-touch function was completed on the driver layer., the multi-point data of IC on the touch screen can be successfully reported at the same time, and users can experience the operation of touching at two or even five points at the same time on the touch screen.
Six.The touch screen module is tested in detail, and some problems found in the testing process are solved. Finally, the system stability, excellent performance and good user experience are achieved.
Touch screen is widely used in China, which is mainly for public information inquiry.Such as telecommunication bureau, tax bureau, bank, electric power and other departments of business inquiries;Urban street information query;In addition, it is used in leading office, industrial control, military command, electronic games, ordering songs and food, multimedia teaching, real estate presale, etc.In the future, touch screens will also enter the home.