//使用前请先定义keyscan为单片机的

//某个端口,如#define keyscan P1

//程序中扫描信号从keyscan高4位输出，

//键值返回信号从keyscan低4位读入，

//故使用时硬件电路需要与之相对，

//或者把软件中相应地方修改即可-/ / use the former post keyscan definition of SCM / / a port, keyscan such as # define P1 / / scanning process signals from four keyscan high output / / keys to a signal from the four low-keyscan read, / / use it when necessary hardware circuit Correspondingly, / / or software which can be revised accordingly places