怎样用51单片机实现累加计时和倒计时,并用六个共阴极数码管显示出来。用...答:include<reg51.h>unsigned char ledtab[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,0xff};unsigned char sec,min,hour,scanled;unsigned char key,mode,time; unsigned char disdat[6];bit upbit;sbit keyu=P3^0;sbit keyd=P3^1;...