3个ＩＯ轻松实现１６个按键功能，附件小含有原理图与在keil下编译通过的可供９６００打印的键值。这种新型电路具有使用非常稳定，电路简单，比４*４电路更节约资源，代码简单-Three IO easily implement 16 keys function, small attachments contain principle diagram and passed under the keil compiler can supply 9600 printed key values. This new circuit using a very stable, circuit is simple, save resources, more than 4* 4 circuit code simple