[ngochiep]

THIEÁT KEÁ ÑOÀNG HOÀ SOÁ DUØNG PIC 16F877A 
//*Write         :
//*Hardware      :PIC16f877A
//*Compiler      :CCS C
//*=========================================
#include<16F877A.h>
#include<def_16F877a.h>
#fuses NOWDT,PUT,HS,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use fast_io(b)
#use fast_io(d)

int8 i,dvis,chucs,dvim,chucm,dvih,chuch;
int32 a,b;
int32 h,k;
int32 bien;
const unsigned char dig[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};

void hienthi()
{
   i=0;
   while(i<24)
   {
      portd=0xfe;
      portb=dig[dvis];
      delay_us(6900);
      portd=0xfd;
      portb=dig[chucs];
      delay_us(6900);
      portd=0xfb;
      portb=dig[dvim];
      delay_us(6900);
      portd=0xf7;
      portb=dig[chucm];
      delay_us(6900);
      portd=0xef;
      portb=dig[dvih];
      delay_us(6900);
      portd=0xdf;
      portb=dig[chuch];
      delay_us(6900);
      i++;
   }
}

void chuyendoi()
{
   b=a/3600;
   a=a%3600;
   h=a/60;
   a=a%60;
   k=a;
   chucs=k/10;
   dvis=k%10;
   chucm=h/10;
   dvim=h%10;
   chuch=b/10;
   dvih=b%10;
}

void main()
{
   trisb=0x0;
   trisd=0x0;
   bien=0;
   while(1)
   {
      bien=bien+1;
      if(bien==86400)
      {
         bien=0;
      }
      a=bien;
      chuyendoi();
      hienthi();
   }