LCD实现菜单功能，本人所写，界面切换使用的是质数法，对于不喜欢用指针，或用的不熟练的筒子有莫大帮助，这也是一种实现方法-LCD with menu function, I wrote, interface switching method used is a prime number, who do not like to use the pointer, or unskilled use of great assistance to the cheese, which is a method