说明：  电阻式触摸屏坐标算法 电阻式触摸屏 触摸屏和51单片机接口，可以使一些小系统的操作更加方便、快捷。使用触摸屏时最重要的问题是确定坐标位置，即确定触点位置是否在该键的有效区域之内。
(Resistive Touch Screen coordinates algorithm Resistive Touch Screen Touch Screen and 51 single-chip interface, can make some small operation of the system more convenient, fast. When using the touch screen the most important issue is to determine the coordinates of the location, that is, to determine whether the location of contacts in the key of effective regions.)