基于单片机的数字时钟怎么做?

#include
#define uchar unsigned char
#define uint unsigned int
sbit dula=P2^6;
sbit wela=P2^7;
sbit rs=P3^5;
sbit lcden=P3^4;
sbit s1=P3^0;
sbit s2=P3^1;
sbit s3=P3^2;
sbit rd=P3^7;
uchar count,s1num;
char miao,shi,fen;
uchar code table[]=" 2007-7-30 MON";
uchar code table1[]=" 00:00:00";
void delay(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}

void write_com(uchar com)
{
rs=0;
lcden=0;
P0=com;
delay(5);
lcden=1;
delay(5);
lcden=0;
}

void write_date(uchar date)
{
rs=1;
lcden=0;
P0=date;
delay(5);
lcden=1;
delay(5);
lcden=0;
}

void init()
{
uchar num;
dula=0;
wela=0;
lcden=0;
// fen=59;
// miao=53;
// shi=23;
write_com(0x38);
write_com(0x0c);
write_com(0x06);
write_com(0x01);
write_com(0x80);
for(num=0;num<15;num++)
{
write_date(table[num]);
delay(5);
}
write_com(0x80+0x40);
for(num=0;num<12;num++)
{
write_date(table1[num]);
delay(5);
}
TMOD=0x01;
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
EA=1;
ET0=1;
TR0=1;
}

void write_sfm(uchar add,uchar date)
{
uchar shi,ge;
shi=date/10;
ge=date%10;
write_com(0x80+0x40+add);
write_date(0x30+shi);
write_date(0x30+ge);
}

void keyscan()
{
rd=0;
if(s1==0)
{
delay(5);
if(s1==0)
{ s1num++;
while(!s1);
if(s1num==1)
{
TR0=0;
write_com(0x80+0x40+10);
write_com(0x0f);
}
}
if(s1num==2)
{
write_com(0x80+0x40+7);
}
if(s1num==3)
{
write_com(0x80+0x40+4);
}
if(s1num==4)
{
s1num=0;
write_com(0x0c);
TR0=1;
}

}
if(s1num!=0)
{
if(s2==0)
{
delay(5);
if(s2==0)
{
while(!s2);
if(s1num==1)
{
miao++;
if(miao==60)
miao=0;
write_sfm(10,miao);
write_com(0x80+0x40+10);

}
if(s1num==2)
{
fen++;
if(fen==60)
fen=0;
write_sfm(7,fen);
write_com(0x80+0x40+7);
}
if(s1num==3)
{
shi++;
if(shi==24)
shi=0;
write_sfm(4,shi);
write_com(0x80+0x40+4);
}
}
}
if(s3==0)
{
delay(5);
if(s3==0)
{
while(!s3);
if(s1num==1)
{
/* if(miao==0)
{
miao=59;
write_sfm(10,miao);
write_com(0x80+0x40+10);
}*/
miao--;
if(miao==-1)
miao=59;
write_sfm(10,miao);
write_com(0x80+0x40+10);
}
if(s1num==2)
{
fen--;
if(fen==-1)
fen=59;
write_sfm(7,fen);
write_com(0x80+0x40+7);
}
if(s1num==3)
{
shi--;
if(shi==-1)
shi=23;
write_sfm(4,shi);
write_com(0x80+0x40+4);
}
}
}
}
}
void main()
{
init();
while(1)
{
keyscan();

}
// while(1);
}

void timer0() interrupt 1
{
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
count++;
if(count==18)
{
count=0;
miao++;
if(miao==60)
{
miao=0;
fen++;
if(fen==60)
{
fen=0;
shi++;
if(shi==24)
{
shi=0;
}
write_sfm(4,shi);
}
write_sfm(7,fen);
}
write_sfm(10,miao);

}
}

这个是数字时钟的源程序，用12864夜晶显示。

用中断实现数码管扫描显示，按键部分用定时扫描做，就这个思路，自己想想该怎么做吧！

这个问题太简单也太复杂了，原理很简单，但要想让代码正确的跑起来，很麻烦，必须有扎实的设计功底，再说数字钟也有简单复杂之分，自己干吗，baidu有大把的例子