//****************************************************************
// MULTLED.C    Driving a multiplexed 7-Segment LED display
//
//
// Version: 1.1
//
//
// By: J. Winpenny
//
// Date: 15/12/03
//
//
//****************************************************************


#define COMMON_CATHODE_LED
// ***** #define COMMON_ANODE_LED *******


#define LED_SEGMENT_PORT PORTD     // Set PORT selecting LED segments
#define LED_MULTIPLEX_PORT PORTC // Set PORT for multplexing digits
#define NUM_LEDS 4                 // Set number of LEDs connected

//***********************************
// PORT Connections for LED
//***********************************
//                 Segment of LED
//***********************************
//                 g f e d c b a
//
// Bit position    6 5 4 3 2 1 0
//***********************************


#define COUNT_INTERVAL 4500 // Set Count rate
#define COM_RELOAD 1
#define TIMER_BIT 0x01


char TRISC@0x87;
char TRISD@0x88;
char PORTD@0x08;

unsigned char cTimerFlag;
unsigned char sLedArray[NUM_LEDS];
unsigned int iCountIntervalTimer;
unsigned char cLedPos;

void UpdateLEDs( void );
void DriveLED( unsigned char cData, unsigned char cNumber );
void IncrementDisplayedNumber(void);




void interrupt( void )
{

   if ( ( INTCON & 0x04 ) != 0 )     // If the TIMER0 times-out
   {
     cTimerFlag = 1;

     if ( iCountIntervalTimer != 0 ) iCountIntervalTimer--;  // Increment count timer

     TMR0 = COM_RELOAD;
     clear_bit( INTCON, T0IF );
   }


}


void main(void)
{
 char c;
  //********************************************
  //         Target specific setup

  TRISC = 0;         // Set PORT C to all outputs
  TRISD = 0;        // Set PORT D to all outputs
  //********************************************


  cTimerFlag = 0;                // Reset the timer
  iCountIntervalTimer = 0;
                                // Initialise LED to display ZERO
  for( c=0; c< NUM_LEDS; c++ ) sLedArray[c] = 0;


  while(1)
  {

     if ( cTimerFlag )               // when the timer times out
     {                               // update the display

       cTimerFlag &= ~TIMER_BIT;    // Reset timer flag

                                   // Increment the value displayed
                                   // when the larger timer times out
       if ( iCountIntervalTimer == COUNT_INTERVAL )
       {
         IncrementDisplayedNumber();
         iCountIntervalTimer = 0;
       }

          UpdateLEDs();               // Update the Multiplexed display

     }



  }


}


//**************************************************
// Increment the number displayed on the LEDs
//**************************************************
void IncrementDisplayedNumber(void)
{
char c;
char cTmp;
//char *p;   No pointer on C2C
char cRollover = 0;


  //p = sLedArray;

  for ( c=0; c < NUM_LEDS; c++)
  {
        cTmp = sLedArray[c];

        if ( ( cTmp + (1 + cRollover) )  > 9 )
        {
           sLedArray[c] = 0;
           cRollover = 1;
        }
        else
        {
          sLedArray[c] = sLedArray[c] + 1 + cRollover;
        }

        //p++;
  }

}


//**************************************************
// Update the LED display
//**************************************************
void UpdateLEDs( void )
{

  if ( cLedPos > NUM_LEDS-1 ) cLedPos = 0; // Test for max LED number

  DriveLED( sLedArray[cLedPos], cLedPos ); // Update the display for the
                                           // this digit.

  cLedPos++;                               // Next LED

}

//**************************************************
// Display a number 0 - 9 ( binary ) on a 7 SEG LED
//**************************************************
void DriveLED( unsigned char cData, unsigned char cNumber )
{
unsigned char cTmp;

#ifdef COMMON_CATHODE_LED
  char CommonCathode7SEG[] = { 0x3f,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x67 };
#endif

#ifdef COMMON_ANODE_LED
 char CommonAnode7SEG[] = { 0x40,0x79,0x24,0x30,0x19,0x12,0x02,0x78,0x00,0x18 };
#endif

typedef unsigned char DIGIT_POSITION_TYPE;

enum DIGIT_POSITION_TYPE
{
   ZERO = 0x01,
    ONE = 0x02,
    TWO = 0x04,
  THREE = 0x08,
   FOUR = 0x10,
   FIVE = 0x20,
   SIX  = 0x40,
  SEVEN = 0x80

}

DIGIT_POSITION_TYPE cDigitSel;


       cDigitSel = cNumber;                       // Obtain select bit patern for LED number n

       #ifdef COMMON_CATHODE_LED
              LED_MULTIPLEX_PORT = cDigitSel;  // Select the LED required
       #endif
       #ifdef COMMON_ANODE_LED
                 LED_MULTIPLEX_PORT = ~DigitSel;
       #endif


       if ( Number < 10 )                     // So we don't exceed the array bounds
       {
                                              // Select segments for cData
        #ifdef COMMON_CATHODE_LED
               LED_SEGMENT_PORT = CommonCathode7SEG[Number];
        #endif

        #ifdef COMMON_ANODE_LED
               LED_SEGMENT_PORT = CommonAnode7SEG[Number];
        #endif

       }

}