Touch Screen Technology and Its Driver Design in uCLinux

摘要

Hardware principle of touch screen input system and its driver design in uCLinux were presented in this work. With the respect of hardware, it introduced working mechanism of four-wire resistive touch screen and method of calculating coordinate. Then it presented the hardware connection of touch screen input system including touch screen, touch screen control chip and Microcontroller Unit. With respect of software, it analyzed the characteristic of driver design in uCLinux. Then it divided touch screen working process into six states which were 'start', 'idle', 'wait', 'read', 'error', 'end' and defined the state transition. On this basis, Touch screen driver design was introduced, which mainly included initialization function, clean function, device-opening function, device-releasing function, coordinates-reading function and parameters-setting function. It also gave the arithmetic converting touch screen coordinate to application coordinate.