/*   originally http://www.kmitl.ac.th:80/~kswichit/clock/clock.htm, via wayback cache
   CLOCK CONTROLLER V2.0
   89C2051 + 4-digit 7-SEG led + 2-key switch
   Simple Digital Clock demostrates scanning LED and key switch.
   The clock has 1-bit output port P3.7 for driving AC load through MOC3040+triac.
   
 
           *    ****       ****    ****
           *   *    *  *  *    *  *    *
           *   *    *     *    *  *    *
           *    ****      *    *  *    *
           *   *    *     *    *  *    *
           *   *    *  *  *    *  *    *
           *    ****       ****    ****

              set                 set 
             HOUR                 MIN  


   Copyright (c) 2006 WICHIT SIRICHOTE, kswichit@kmitl.ac.th
*/

#include <reg52.h>               /* special function register declarations   */
                                  /* for the AT89C52       */
#include <stdio.h>      

// preset set time on/off are predefined in rom, user may change it here

#define onHour1 19
#define onMin1 00
#define offHour1 21
#define offMin1 30

unsigned  char sec100,sec,sec5,min,hour,flag1,command,temp,opto;
unsigned char i,digit, buffer[4];
char cputick,key,delay,count1;
unsigned char convert[10] = {0x3F,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};

void pause(int); 
void scanLED();


void setmin();
void sethour();
void showOnce();
void savetimeOff1();

void time();
void timeToBuffer();
void blink();
void offmsd();
void keyexe();
void keydelay();
void comparetime();


void timer0int (void)  interrupt 1  using 1  {
	TH0 |= 0xd8;  // reload timer 0 with d8f0h
	TL0 |= 0xf0;
    cputick++;
	time();       // update realtime clock
           
}

void main()
{
  EA = 1;
  ET0 = 1;  // or IE |= 0x82;   /* set bit EA and Timer0 enable */ 
  TMOD |= 0x01; /* timer 0 run 16 bit counter */
  TR0 = 1; //or TCON |= 0x10; /* run timer 0 */
  opto = 0xff;
  cputick = 0;
  hour = 18;
  min = 0;
  sec = 0;
  key = -1;
  flag1 = 0;
 
  count1 = 0;
  buffer[0] = 0x40;
  buffer[1] = 0x40;
  buffer[2] = 0x40;
  buffer[3] = 0x40;

  while(1)
  {
    while ( cputick < 1)
    scanLED();

    cputick = 0;

/*------------- the following tasks execute every 10ms ------*/

    timeToBuffer();
    blink();
    offmsd();
    keyexe();
    keydelay();
    comparetime();
   
/*-----------------------------------------------------------*/
   }
}

/* update real-time clock  */
void time ()

{
   if (++sec100 >= 100)       /* 100 * 10 ms = 1 s */
   {sec100 = 0;
    flag1 |= 0x05;   /* set bit 0, bit 2 */
    temp = 50;
    if (++sec >= 60)
    {sec = 0;
     flag1 |= 0x02; /* set bit 1 */
       if (++min >= 60)
     {min = 0;
         if (++hour >= 24)
     {hour = 0;

    }
  }
 }
}
}

void scanLED() /* scan 4-digit LED and 4-key switch, if key pressed key = 0-3
else key = -1 */

{
    int i;
    digit = 0x08;
    key = -1;
    for( i = 0; i < 4; i++)  /* 4-DIGIT scanning */
    {
        P3 = ~digit & opto;  /* send complement[digit] */
        P1 = buffer[i];  /* send segment */
        pause(10);         /* delay a while */
        P1 = 0x00;        /* off LED */
        if ((P3 & 0x10) == 0) /* if key pressed P3.4 became low */
           key = i;       /* save key position to key variable */
        digit>>=1;        /* next digit */
    }
}


void timeToBuffer()
{
  if(flag1&0x40) // run only when any key was pressed
  {
    buffer[0] = convert[min%10];
    buffer[1] = convert[min/10];
    buffer[2] = convert[hour%10];
    buffer[3] = convert[hour/10];
  } 
}

void blink()
{
    if(flag1 & 0x04) /* check bit 2 if set decrement temp until zero */
     {temp--;
        if (temp != 0)
                {
                  buffer[2] |= 0x80;
                }
                else( flag1 &= ~0x04);
      }
}


void keyexe()
{
    if (key != -1)
    {
        if ((flag1 & 0x80) == 0)  /* within 0.5 sec after 1st press
                                    the following execution is not allowed */
            {
                flag1 |= 0x80;
                delay = 50;

      switch(key){
        case (0): /* key position 0 */
        ;
        break;
        case (1): /* key position 1 */
        ;
        break;
        case (2): /* key position 2 */
        setmin(); /* service key 2 */
        break;
        case (3): /* key position 3 */
        sethour();
                  }
                }

    }
}

void sethour()
{
    flag1 |= 0x40; // enable time upldate
    if ( ++hour== 24) hour = 0;

}

void setmin()
{
     flag1 |= 0x40; // enable time upldate
    sec = 0;
    if( ++min == 60 ) min = 0;
}


void keydelay()
{
    if (flag1 & 0x80)
        {
          delay--;
        if(delay == 0) flag1 &= ~0x80;
        }
}

void comparetime()
{
  if(flag1 & 0x40) // compare time only when user enter new time
  {
    if(flag1 & 0x01)
    {
        flag1 &= ~0x01;
    if(hour == onHour1 && min == onMin1)
            opto = 0x7f; /* clear P3.7 turning opto on   */
    if(hour == offHour1 && min == offMin1)
            opto = 0xff; /* set bit P3.7 turning opto off */
    }
   }
}

void offmsd()

{
    if (buffer[3] == 0x3f)    /* if msd = '0' then put blank unstead */
       buffer[3] = 0x00;
}


void pause(j)
int j;
{
   int i;
   for (i = 0; i < j; i++) continue;
}