单片机：c语言实现秒表计数（按键开始，结束，重置）

代码中有详细的注释：

#include<reg52.h> sbit WEI=P2^7;sbit DUAN=P2^6;sbit L1=P3^4;unsigned char code dofly_DuanMa[11]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x40};// 显示段码值0~9unsigned char code dofly_WeiMa[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f};//分别对应相应的数码管点亮,即位码void delay(int t){   while(t--);}  //第一个参数i代表控制第几个数码管，n代表要显示的数字void Screen(int i,int n){     P0=0;     DUAN=1; DUAN=0;          P0=dofly_WeiMa[i];     WEI=1; WEI=0;         P0=dofly_DuanMa[n];      DUAN=1;       DUAN=0;}int sec;int num;int i;int flag;int main(){    flag=1;    i=0;    num=0;sec=0;  WEI=0;  DUAN=0;   //开中断  EX0=1;          IT0=1;           EX1=1;          IT1=1;               //定时器初始化    TMOD |= 0x01;           EA=1;               ET0=1;              TR0=1;      L1=0;    while(1)   {                   if(num>=10) Screen(3,num/10); Screen(4,num%10);     delay(10);     Screen(5,10); Screen(6,sec/10);     Screen(7,sec%10);}         return 0;}void Timer_0() interrupt 1 using 1{         TH0=(65536-10000)/256;   TL0=(65535-10000)%256;   if(flag==1)   {     i++;    sec++;if(sec==100) //0.1mssec=0;     if(i==101)//1s     {        i=0;    num++;    if(num==15)    num=0;     }   }}void ACTION1() interrupt 0 {    flag=!flag;}void ACTION2() interrupt 2 {     if(flag==0)  {    Screen(7,0);    num=0;sec=0;  }}

</reg52.h>