单片机原理与接口技术/第12章8051单片机接口扩展技术 single chip microcomputer include <reg51.h> include sabsacc. h> #define io XBYTE[OX7fff] void maino i unsigned char state=OXff, temp while(1) i temp=io if(state!=temp) i state=temp io=state:第12章 8051单片机接口扩展技术 #include <reg51.h> #include <absacc.h> #define io XBYTE[0x7fff] void main() { unsigned char state=0xff,temp; while(1) { temp=io; if(state!=temp) { state=temp; io=state; } } }