#include<reg51.h>
#define uchar unsigned char;
#define uint unsigned int;
uchar position;           
uchar tt;             
uint second;       
uchar minute;
uchar hour;    
uint bz=0,bza=0;
uchar code table[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};//?--9
sbit smg_q = P2^0;  //数码管?
sbit smg_b = P2^1; 
sbit smg_s = P2^2;
sbit smg_g = P2^3;
sbit key1=P3^2; //开关
sbit key2=P3^3;
sbit key3=P3^4;
sbit key4=P3^5;
void keyscan(); //检查是否按键，开启 暂停 K1继续 K2暂停  K3 重新开始
void display(unsigned int second);//显示时分
void delay(unsigned int timer);//延时
void init();  //初始化
void main()
{
    tt=0;
    init();                                    
  while(1)
  {
   if(tt==20)
    {                          
      tt=0;
            second++;
            
      

      }
    keyscan();
    display(second);      
    delay(1);
  }
}

void keyscan()
{ if(key1==0) //如果按键1
   {
     //TR0=0;
     TR0=1;
   }
  if(key2==0)                 // ???
   {
     TR0=0;
     //TR0=1;
   }
  if(key3==0)                 // ???
   {
     tt=0;
         init();
         TR0=1;
     //TR0=1;
   }
}
void init()
{
  //tt=0;
  position=0;               
  second=0; 
  minute=0;        
  hour=0;   
  smg_q=1;
  smg_b=1;
  smg_s=1;
  smg_g=1;
  key1=1;
  key2=1;
  TMOD=0X01;  
  TH0=0x4c;        
  TL0=0x00;
  EA=1;                
  ET0=1;              
  TR0=1;              
}

void t0() interrupt 1//中断服务程序：0为外部中  0 ，1定时器0，2外部中断1，3定时器1，4串行中断
{
    TH0=0x4c;        
  TL0=0x00;
    //TH0=(65536-50000)/256; //定时器T0重新赋值：0X3C
  //TL0=(65536-50000)%256;//0XB0 15536转成16进制为：3CB0
  tt++; 
    
}
void display(unsigned int second)
{
    P0=0XFF;                             
  switch(position)
  {
   case 0:              
          smg_g=1;
          smg_q=0;
          P0=table[second/1000]; 
          break;
   case 1:
          smg_q=1;        
          smg_b=0;        
          P0=table[(second-second/1000*1000)/100];
          //if(tt>=10)
             //P0&=0xff; //第二数码管右下角的点（0x7f)
          break;
   case 2:    
         smg_b=1;                  
         smg_s=0;                  
         P0=table[(second-second/100*100)/10];
         break;
  case 3:                       
        smg_s=1;
        smg_g=0;
                
        P0=table[(second-second/100*100)%10];
                
                
                 if(tt>=10)
             P0&=0x7f; //第二数码管右下角的点（0x7f)
        break;
 }
  position++;               
 if(position>3)
   position=0;      
}
void delay(unsigned int time)
{                
   unsigned int x,y;
   for(x=time;x>0;x--)
     for(y=110;y>0;y--);
}