【单片机期中测试】9.定时器实现简单的秒表程序

#include<reg52.h>
#define uc unsigned char
sbit key=P2^0;
uc start=1;m=0,i=0;
void delay(uc c)
{
  uc a,b;
  for(;c>0;c--)
    for(a=38;a>0;a--)
      for(b=130;b>0;b--);
}
void ss() interrupt 3
{
  TH1=15536/256;
  TL1=15536%256;
  i++;
  if(i%20==0)
  {
    if(m>60) m=0;
    P1=m/10*16+m%10;
    m++;
  }
  TF1=0;
}
void main()
{
  TMOD=0x10;
  TH1=15536/256;
  TL1=15536%256;
  ET1=1;
  EA=1;
  TR1=0;
  while(1)
  {
    if(key==0)
    {
      TR1=!TR1;
      if(TR1==1)
      {
        TH1=15536/256;
        TL1=15536%256;
        i=0;m=0; P1=m/10*16+m%10;
      }
      delay(1);
      while(key==0);
      delay(1);
    }
  }
}