用三个独立按键实现按下第一个时计时停止，按下第二个时计时开始，按下第三个时计数值清零从头开始，秒表设计！！！！

#include<reg52.h>
#include<intrins.h>
#define uchar unsigned char
#define uint unsigned int
sbit dula=P2^6;
sbit wela=P2^7;
sbit key1=P3^5;
sbit key2=P3^4;
sbit key3=P3^3;
sbit key4=P3^2;
uchar code tab[]={
0xc0,0xf9,0xa4,0xb0,
0x99,0x92,0x82,0xf8,
0x80,0x90,0x88,0x83,
0xc6,0xa1,0x86,0x8e};
uchar temp,bai,shi,ge,aa,flag,flag1,t0,t1;
uint shu;
void display(uchar bai,uchar shi,uchar ge);
void init();
void delay(uint z);

void main()
{
init();
while(1)
{
display(bai,shi,ge);
if(key1==0)
{
delay(5);
if(key1==0)
TR0=0;

}
if(key2==0)
{
TR0=1;
display(bai,shi,ge);

}
if(key3==0)
{

shu=0;
display(bai,shi,ge);

}
}
}

void init()
{
shu=0;
TMOD=0x01;
TH0=(65536-10000)/256;
TL0=(65536-10000)%256;
EA=1;
ET0=1;
TR0=1;

}

void time0() interrupt 1
{
TH0=(65536-10000)/256;
TL0=(65536-10000)%256;
t0++;
if(t0==1)
{
t0=0;
bai=shu/100;
shi=shu%100/10;
ge=shu%10;
shu++;
if(shu==1000)
shu=0;
}

}
void display(uchar bai,uchar shi,uchar ge)
{
wela=1;
P2=0xfe;
wela=0;
dula=1;
P0=tab[bai];
dula=0;
delay(5);

wela=1;
P2=0xfd;
wela=0;
dula=1;
P0=tab[shi];
dula=0;
delay(5);

wela=1;
P2=0xfb;
wela=0;
dula=1;
P0=tab[ge];
dula=0;
delay(5);

}
void delay(uint z)
{
uint x,y;
for(x=0;x<z;x++)
for(y=0;y<110;y++);

}