單片機(jī)60s倒計(jì)時(shí)c51程序

#include <reg51.h>
#define uchar unsigned char
sbit P13=P1^3;
sbit P14=P1^4;
uchar c,i,a=60,z;
uchar code Numcode[]={0XC0,//;0
                0XF9,//;1
                0XA4,//;2
                0XB0,//;3
                0X99,//;4
                0X92,//;5
                0X82,//;6
                0XF8,//;7
                0X80,//;8
                0X90,//;9
};
 void delay(z)
{ while(z--);
}
void main()
{TMOD=1;
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
c=0;
i=0;
EA=1;
ET0=1;
TR0=1;
while(1)
 { if(c==20)
  { c=0;
  a--;}
  if(a>=0)
  {i=a/10;
P13=1;
  P0=Numcode[i];
P14=0;
   delay(20);
 P14=1;
   i=a%10;
  
    P0=Numcode[i];
  P13=0;
  delay(10);}
 
 else
 {a=60;}
}
}
void timer0() interrupt 1
 {TH0=(65536-50000)/256;
  TL0=(65536-50000)%256;
  c++;
  }