//時鐘實驗
//功能：第一，二位數碼管顯示時
//三，四位數碼管顯示分
//五，六位數碼管顯示秒
#include <reg52.h>
#define const_time 400;   //100x5ms=500ms=0.5s
unsigned int buff_time;  //buffer for storing the counts
unsigned char data time;
sbit light0 = P1^0; //the light0 bit
sbit DAT164 =P0^6;  //the bit of HC164's data
sbit CLK164 =P0^7;  //the bit of HC164's clock
sbit onebit=P0^0;   //one of the "8bit led" 
sbit twobit=P0^1; 
sbit thrbit=P0^2;   //one of the "8bit led" 
sbit foubit=P0^3; 
sbit fivbit=P0^4;   //one of the "8bit led" 
sbit sixbit=P0^5; 

bit LED_Buffer;
unsigned char data wei;
unsigned char data hour;
unsigned char data min;
unsigned char data sec;
unsigned char data hour_hi;
unsigned char data min_hi;
unsigned char data sec_hi;
unsigned char data hour_low;
unsigned char data min_low;
unsigned char data sec_low;

unsigned char data LED;
code unsigned char LEDMAP[] =  // define the table of the "8bit led" 
{
0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x88,0x83,0xA7,0xA1,0x86,0x8E
};

void send164() //the function of send the data to the "74HC164"
{
	 unsigned char data j;
	 for (j = 0; j < 8; j++) 
	   {
	     if (LED & 0x80) DAT164 = 1; 
		         else DAT164 = 0;
	      CLK164 = 1;
	      CLK164 = 0;
	      LED <<= 1;
       } 
}

void main() 
{ 
	  TMOD=0x01;   //set the timer's mode
	  TH0=(65536-2500)/256; //fill the timer0's higher register 
	  TL0=(65536-2500)%256; //fill the timer0's lower register
	  IE=0x82;   //EA=1,IT0=1
	  LED_Buffer=0;
	  light0=0;
	  buff_time=const_time;
	  TR0=1;     //start the timer!
	  hour=0;
	  min=0;
	  sec=0;
	  while(1)
	  {
	     light0=LED_Buffer;
      }  
}


void T0Int() interrupt 1 using 3
{
	 TH0=(65536-2500)/256; //fill the timer0's higher register 
	 TL0=(65536-2500)%256; //fill the timer0's lower register 
	 buff_time--;
	 wei=buff_time%6;
	 hour_hi=hour/10;
	 hour_low=hour%10;
	 min_hi=min/10;
	 min_low=min%10;
	 sec_hi=sec/10;
	 sec_low=sec%10;

     switch(wei)
	{
	 case 5:
	 onebit=0;   
	 twobit=1; 
	 thrbit=1;   
	 foubit=1; 
	 fivbit=1;  
	 sixbit=1; 
	 LED=LEDMAP[hour_hi];
	 send164();
	 break;
	
	 case 4:
		 onebit=1;   
		 twobit=0; 
		 thrbit=1;   
		 foubit=1; 
		 fivbit=1;  
		 sixbit=1; 
		 LED=LEDMAP[hour_low];
		 LED=LED&0x7f;
		 send164();
		 break;
	
	 case 3:
		 onebit=1;   
		 twobit=1; 
		 thrbit=0;   
		 foubit=1; 
		 fivbit=1;  
		 sixbit=1; 
		 LED=LEDMAP[min_hi];
		 send164();
		 break;
	
	//////////////
	case 2:
		 onebit=1;   
		 twobit=1; 
		 thrbit=1;   
		 foubit=0; 
		 fivbit=1;  
		 sixbit=1; 
		 LED=LEDMAP[min_low];
		 LED=LED&0x7f;
		 send164();
		 break;
	
	 case 1:
		 onebit=1;   
		 twobit=1; 
		 thrbit=1;   
		 foubit=1; 
		 fivbit=0;  
		 sixbit=1; 
		 LED=LEDMAP[sec_hi];
		 send164();
		 break;
	
	 case 0:
		 onebit=1;   
		 twobit=1; 
		 thrbit=1;   
		 foubit=1; 
		 fivbit=1;  
		 sixbit=0; 
		 LED=LEDMAP[sec_low];
		 send164();
		 break;
	}
	
	  
	 if (buff_time==0)
	  {
		 buff_time=const_time; // refill the buffer
		 LED_Buffer=!LED_Buffer;  // opposite the LED display
		 sec++;
		 if (sec==60) 
		   {
				min++;
				sec=0;
				if (min==60)
				   {
						hour++;
						min=0;
						
						if (hour==60)
						hour=0;
				    }
	    
        	}
    }

}