3.20

#include<reg52.h>


extern void InitLcd1602();
extern void LcdShowStr(unsigned char x,unsigned char y,unsigned char *str);
void ShowBcdByte(unsigned char x,unsigned char y,unsigned char bcd);
 
unsigned char sec=58 ;
unsigned char min=59;
unsigned char hour=19 ;
bit flag = 0;


void main()
{
EA = 1;
     TMOD = 0x01;
TH0 = 0xFC;
TL0 = 0x67;
ET0 = 1;
     TR0 = 1; 


InitLcd1602();
LcdShowStr(4,1,"  :  :  ");


while(1)
{
   if(flag == 1)
{
flag = 0;
sec++;
if(sec >= 60)
{
   sec = 0;
min++;
if(min >= 60)
{
   min = 0;
   hour++;
if(hour >= 24)
{
   hour = 0;
}
}
}
   }
ShowBcdByte(4,1,hour);
   ShowBcdByte(7,1,min);
   ShowBcdByte(10,1,sec);
 }
}


void ShowBcdByte(unsigned char x,unsigned char y,unsigned char bcd)
{
     unsigned char str[3];


str[0] = (bcd/10)+'0';
str[1] = (bcd%10)+'0';
str[2] = '\0';
LcdShowStr(x,y,str);
}


void InterruptTimer0() interrupt 1
{
static unsigned int cnt = 0;


     TH0 = 0xFC;
TL0 = 0x67;
cnt++;
if(cnt >= 1000)
{
    cnt = 0;
flag = 1;
}  
}