假设51单片机，P1口点亮，低电平点亮。unsigned char x =0xfe,i=0;for(i=0,i＜8;i++){x=_crol_(x,1);P1=x;delay500ms();}for(i=0,i＜8;i++){x=_cror_(x,1);P1=x;delay500ms();}
