MSP430 - 24hr Clock with Calendar

//************************************************
// MSP430G2553 Clock/Calendar
//************************************************

/*-------------------------------------------------
2013.07.23 - MrChips

Notes: LCD E has been changed from P2.6 to P1.6
--------------------------------------------------*/

#include "io430.h"

//---------------------------------------------------
// Global Variables
//---------------------------------------------------

short Year, Month, Day, Weekday;
short Hour, Minute, Second;
short DaysThisMonth;

char Months[13][4] = { " ", "JAN", "FEB", "MAR", "APR", "MAY", "JUN",
                        "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"};

char Days[8][12] = {" ", "SUNDAY ", "MONDAY ", "TUESDAY ",
                     "WEDNESDAY ", "THURSDAY", "FRIDAY ", "SATURDAY "};

short DaysInMonth[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

//---------------------------------------------------
// Defines
//---------------------------------------------------

#define title1 "MrChips Clock"
#define title2 "Version 1.00"

#define TRUE 1
#define FALSE 0
#define ON 1
#define OFF 0

#define LED1 P1OUT_bit.P0

// ASCII codes

#define SP 32
#define COLON 58

//---------------------------------------------------
// Function Prototypes
//---------------------------------------------------

short DaysInThisMonth(short year, short month);

//---------------------------------------------------
// LCD Interface
//---------------------------------------------------

void LCD_init(void);
void LCD_ready(void);
void LCD_ir(char ch);
void LCD_dr(char ch);
void LCD_txt(char *s);
void LCD_Home(void);
void LCD_Clear(void);
void LCD_Line1(void);
void LCD_Line2(void);
void LCD_Line3(void);
void LCD_Line4(void);
void LCD_Posn(char n);

// define LCD interface on PORT2
#define LCD_OUT P2OUT
#define LCD_IN P2IN
#define LCD_DDR P2DIR
#define LCD_RS P2OUT_bit.P4
#define LCD_RW P2OUT_bit.P5
#define LCD_E P1OUT_bit.P6

void LCD_init(void)
{
  LCD_ir(0x28); // dual line, 4 bits
  LCD_ir(0x06); // increment mode
  LCD_ir(0x0C); // cursor turned off
  LCD_ir(0x10); // cursor right
  LCD_ir(0x01); // clear display
}

void LCD_Clear(void)
{
  LCD_ir(0x01);
}

void LCD_Home(void)
{
  LCD_ir(0x02);
}

void LCD_Line1(void)
{
  unsigned char i;
  LCD_ir(0x80);
  for (i = 0; i < 16; i++)
  {
    LCD_dr(SP);
  }
  LCD_ir(0x80);
}

void LCD_Line2(void)
{
  unsigned char i;
  LCD_ir(0xC0);
  for (i = 0; i < 16; i++)
  {
    LCD_dr(SP);
  }
  LCD_ir(0xC0);
}

void LCD_Line3(void)
{
  LCD_ir(0x94);
}

void LCD_Line4(void)
{
  LCD_ir(0xD4);
}

void LCD_Posn(char n)
// direct positioning where n = 0-79
{
  char ch;
  ch = n;
  if (ch >= 40) ch += 24;
  LCD_ir(ch | 0x80);
}

void LCD_ready(void)
{
  char busy;
  LCD_DDR = 0x30;
  LCD_RW = 1;
  LCD_RS = 0;
  do
  {
    LCD_E = 1;
    // high 4 bits read first
    // busy flag is D7 of LCD = bit 3 of P2IN
    busy = (LCD_IN & 0x08);
    LCD_E = 0;
    LCD_E = 1;
    LCD_E = 0;
  } while (busy);
  LCD_OUT = 0;
  LCD_DDR = 0x3F;
}

void LCD_ir(char ch)
{
  LCD_ready();
  //LCD_RS = 0; // not needed // select instruction register
  //LCD_RW = 0; // not needed
  LCD_OUT |= ((ch >> 4) & 0x0F);
  LCD_E = 1;
  LCD_E = 0;
  LCD_OUT = 0;
  LCD_OUT |= (ch & 0x0F);
  LCD_E = 1;
  LCD_E = 0;
}

void LCD_dr(char ch)
{
  LCD_ready();
  LCD_RS = 1; // select data register
  //LCD_RW = 0; // not needed
  LCD_OUT |= ((ch >> 4) & 0x0F);
  LCD_E = 1;
  LCD_E = 0;
  LCD_OUT = 0;
  LCD_RS = 1;
  LCD_OUT |= (ch & 0x0F);
  LCD_E = 1;
  LCD_E = 0;
}

void LCD_txt(char *s)
{
  while(*s) LCD_dr(*s++);
}

void LCD_bcd5(short n)
  // display 5 digits
{
  short i;
  short d[5];
  for (i = 0; i < 5; i++)
  {
    d[i] = n % 10;
    n = n / 10;
  }
  for (i = 0; i < 5; i++)
  {
    LCD_dr('0' + d[4-i]);
  }
}

void LCD_bcd2(short n)
// display two digits
{
  LCD_dr('0' + n / 10);
  LCD_dr('0' + n % 10);
}

//---------------------------------------------------
// Date & Time Display
//---------------------------------------------------

void ShowDate(void)
{
  LCD_Line1();
  LCD_bcd5(Year);
  LCD_dr(SP);
  LCD_txt(Months[Month]);
  LCD_dr(SP);
  LCD_bcd2(Day);
  LCD_dr(SP);
}

void ShowTime(void)
{
  LCD_Line2();
  LCD_txt(Days[Weekday]);
  LCD_Posn(48);
  LCD_bcd2(Hour);
  LCD_dr(COLON);
  LCD_bcd2(Minute);
  LCD_dr(COLON);
  LCD_bcd2(Second);
}

//---------------------------------------------------
// Hardware Initialization
//---------------------------------------------------

void init(void)
{
   // Stop watchdog timer to prevent time out reset
  WDTCTL = WDTPW + WDTHOLD;

    // Set up 32768Hz crystal
  BCSCTL1 |= DIVA_3; // divide by 8
  BCSCTL3 |= XCAP_3; // select 12pF caps

  P1DIR = 0xFF; // configure output ports
  P1OUT = 0x00;

  P2DIR = 0x3F;
  P2OUT = 0x00;

  // initialize Timer0_A
  TA0CCR0 = 511; // set up terminal count
  TA0CTL = TASSEL_1 + ID_3 + MC_1; // configure and start timer

  // enable interrupts
  TA0CCTL0_bit.CCIE = 1; // enable timer interrupts
  __enable_interrupt(); // set GIE in SR
}

#pragma vector = TIMER0_A0_VECTOR
__interrupt void myTimerISR(void)
{
  if (++Second >= 60)
  { // next mimute
    Second = 0;
    if (++Minute >= 60)
    { // next hour
      Minute = 0;
      if (++Hour >=24)
      { // next day
        Hour = 0;
        if (++Weekday > 7) Weekday = 1;
        if (++Day > DaysThisMonth)
        { // next month
          Day = 1;
          ++Month;
          DaysThisMonth = DaysInThisMonth(Year, Month);
          if (Month > 12)
           { // new year
             ++Year;
             Month = 1;
             DaysThisMonth = 31;  // January
           } // new year
        } // next month
      } // next day
    } // next hour
  } // next minute
  ShowDate();
  ShowTime();
}

//-----------------------------------
// Calendar
//-----------------------------------

void init_Date_Time(void)
{
  Year = 2013;
  Month = 7;
  Day = 23;
  Weekday = 3; // Sunday = 1

  Hour = 21;
  Minute = 59;
  Second = 0;

  DaysThisMonth = DaysInThisMonth(Year, Month);
}

short IsLeapYear(short thisyear)
// is thisyear a leap year?
{
  short result;
  result = FALSE;
  if ( (thisyear % 1000) == 0 )
  { // millenium
    result = ((thisyear / 1000) % 2) == 0;
  } // millenium
  else
  { // not millenium
    if ( (thisyear % 400) == 0)
    { // every 400 years
      result = TRUE;
    } // every 400 years
    else
    { // not 400 years
      if ( (thisyear % 100) == 0)
      { // every 100 years
        result = FALSE;
      } // every 100 years
      else
      { // not 100 years
        if ( (thisyear % 4) == 0)
        { // every 4 years
          result = TRUE;
        } // every 4 years
      } // not 100 years
    } // not 400 years
  } // not millenium
  return result;
}

short DaysInThisMonth(short year, short month)
// how many days in year, month
{
  short days;
  days = 28;
  if (month == 2)
  { // February
    if ( IsLeapYear(year) ) days = 29;
  } // February
  else
  { // Not February
    days = DaysInMonth[month];
  } // Not February
  return days;
}

//-----------------------------------
// Main
//-----------------------------------

void main(void)
{
  init();
  init_Date_Time();
  LCD_init();

  LCD_txt(title1);
  LCD_Line2();
  LCD_txt(title2);

  // enter low power mode
  LPM3;
}

//-----------------------------------
// end of Main
//-----------------------------------