4*4键盘测试程序，只需61或51单片机P0,P1,P2口中的任何一种即可，这里没有用行翻转法实现读键值，比较特变哦-4* 4 keyboard test procedure, only 61 or 51 Singlechip P0, P1, P2 can be any of the mouth, where there is no line inversion method used to achieve reading keys, compare Tebian Oh