说明：  51单片机ADS7846/ADS7843芯片驱动，适合用在4线制触摸屏，它通过标准SPI协议和CPU通信，操作简单，精度高。
(51 ADS7846/ADS7843 chip microcontroller-driven and is suitable for use in the 4-wire Touchscreen, SPI through standard protocols and CPU communication, simple operation and high accuracy.)