缘由怎么用二个数码管做分的倒计时，DP亮灭来计秒,求思路 - 24小时必答区

#include "REG52.h"
sbit K1 = P1^5;
sbit K2 = P1^6;
sbit K3 = P1^7;
sbit BUZ1=P1^0;
bit k=0;
unsigned char code SmZiFu[]={63,6,91,79,102,109,125,7,127,111,128};//0-9.
unsigned char Js=0,miao=0,fen=0;//中断计时
void smxs(unsigned char mz,unsigned char w,unsigned char d)
{
	unsigned char Xd=0;
	P0=255;
	P0=255-(d==1?SmZiFu[mz]:(SmZiFu[mz]|128));//小数点闪烁
	P2=w;
	while(++Xd);
}
void JiShi(/*时间计算*/)
{
		if(Js>=20){Js=0;k=~k;if(++miao>=60){miao=0;if(++fen>=60)fen=0;}}
}
void ZhongDuanSheZhi()
{
	TH0+=0X4c;/*定时器赋初值，定时50ms触发中断，自动补偿方式*/
	TL0+=0X00; 
	TMOD=0X01;
	TR0=1; 
	ET0=1; //开启定时器
	EA=1; //全局中断开关
}
void main()
{
	unsigned char Xd=200,ss=0;
	unsigned int wei=0;
	ZhongDuanSheZhi();
	while(1)
	{
		if(K1==0&&++Xd==0){++fen;miao+=10;while(K1==0)smxs(ss,1,1);Xd=200;}
		smxs(fen/10%10,4,k?0:1);
		smxs(fen%10,8,k?1:0);
		JiShi();//一定要放在最后
	}
}
void ZhongDuan() interrupt 1
{
	++Js;
	TH0+=0X4c;
	TL0+=0X00;        
}