51单片机编写60秒倒计时程序

#include 
#define guan P0
#define wei  P2  
#define uchar unsigned char
#define uint  unsigned int

uint m=0;
uchar a1,a0,k=0,j,k,s=60;
sbit beep=P2^3;
unsigned char code weiyu[]={0x1f,0x2f,0x4f,0x8f}; //代码与P2对应做位处理，显示相应的位
unsigned char code table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,
            0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};//共阴极数码管码表

void delay(unsigned char xms)
{
  for(j=xms;j>0;j--)
     for(k=125;k>0;k--);
}

void display1(uchar wei1,uchar shu)
{
  wei=0xff;
  P0=table[shu];
  wei=wei&weiyu[wei1];
  delay(5);
}

void display(uchar a,uchar b)
{
 display1(2,a);
 display1(3,b);
}

void main()
 {
  TMOD=0x01;
  ET0=1;
  TR0=1;
  EA=1;
 while(1)
 {
  if(m==20)
  {
   m=0;
   s--;
  }
  a1=s/10;
  a0=s%10;
  display(a1,a0);
  if(s==0)
  {
  TR0=0;
  beep=0;
  }
  } 
 }										 
void TO_TIMER () interrupt 1
 {
  TH0=(65536-46080)/256;
  TL0=(65536-46080)%256;
  m++;
 }