unsigned char *p=&PINC;提示错误但是运行正常，求解。
warning: initialization discards qualifiers from pointer target type
unsigned char *p=&PINC;

[解决办法]
看好了：warning不是错误，是警告！
[解决办法]
去掉警告的话，可以这样写，unsigned char *p = (unsigned char*)&PINC;