The Design Of Touch Screen Driver And MMI On Mobile Phone Platform

With the improvement of people's living standard, good man-machine interface (MMI) has become an important criterion for more and more people, as they choose mobile phones and other handheld devices. So, along with the needs of people, man-machine interface design and development has become a very important part of the mobile phone software development system, and meets people grteatly. Friendly, mobile phones and other handheld devices with touch screen functionality, eliminating the need for the keyboard part, increasing the proportion of the screen, more simple intuitive operation, lower power consumption, smaller size, welcomed by all sectors of people.For the development and design staff, the touch screen mobile phone, lacking the keyboard support, needs the developers to makt the coordinates of the controls on the screen more precise, except for the requirements for a higher performance on screen display. It ensures that people can appreciate the rapid response and accurate positioning, not only the successful completion of the touch operating, which can more reflect the humanity of design.In this paper, three aspects had been completed:1. Construction of the hardware platform, According to actual needs, PXA255 chip, Intel's ARM-based framework as a core processor, is responsible for the operation of the whole system, and TI's ADS7846 as the touchscreen driver chip, it will communicate with with the processor via PXA255's SSP (Synchronous Serial Port) in order to achieve the real-time transmission of embedded systems.2. The structures of the system platform, a stable operation platform had been builded with some necessary modules, including boodloader transplanting, document production, core cutting, and the touch screen driver transplanting.3. Touch screen performance optimization, first, the mobile phone touch screen will be optimization on accuracy calibration, through a five-point calibration method, and then the noise will be effectively removed from the mobile phone touch screen by the following methods, filter method, adding a pressure parameter method and reduce the mapped region the effective range. Finally, the above algorithm was checked on a simulator, a comprehensive validation results show that the above algorithms on the simulator achieve the desired results, the the source codes is compiled into the binary files needed by the target mobile phone platform, with the Ann compiler, the required binaries were successfully compiled and generated, and then by the Flash Tool, the binary files were downloaded to the target phone, and then completed a comprehensive validation in the physical phone, including the accuracy and if the noise is effectively removed and the stability of the entire platform with the added algorithms. Experimental results show that the above algorithms can achieve the desired results and it can make a safe and stable operation both in the simulator and the target on the physical phone.