max6921.c

#include <msp430G2553.h>
#include "MAX6921.h"

//Define our pins
#define DATA BIT4  // P1.4
#define CLOCK BIT6 // P1.6
#define LATCH BIT5 // P1.5

void setupMax6921(void){
    P1DIR |= (DATA + CLOCK + LATCH);  // Setup pins as outputs
}
// Pulse the clock pin
void pulseClock(void){
  P1OUT |= CLOCK;
  P1OUT ^= CLOCK;
}

// Writes a value to the specified bitmask/pin. Use built in defines
// when calling this, as the shiftOut() function does.
// All nonzero values are treated as "high" and zero is "low"
void pinWrite(unsigned int bit, unsigned char val){
  if (val){
    P1OUT |= bit;
  } else {
    P1OUT &= ~bit;
  }
}

unsigned int getNum(unsigned int num){
    switch(num){
    //             0b--------ABCDEFGH
    case 0: return 0b0000000011111100;
    case 1: return 0b0000000001100000;
    case 2: return 0b0000000011011010;
    case 3: return 0b0000000011110010;
    case 4: return 0b0000000001100110;
    case 5: return 0b0000000010110110;
    case 6: return 0b0000000010111110;
    case 7: return 0b0000000011100000;
    case 8: return 0b0000000011111110;
    case 9: return 0b0000000011100110;
    default: return 0b0000000000000010;
    }
}


unsigned int getDigit(unsigned int digit){
    switch(digit){
    //             0b--------12345678;
    case 1: return 0b0000000010000000;
    case 2: return 0b0000000001000000;
    case 3: return 0b0000000000100000;
    case 4: return 0b0000000000010000;
    case 5: return 0b0000000000001000;
    case 6: return 0b0000000000000100;
    case 7: return 0b0000000000000010;
    case 8: return 0b0000000000000001;
    default: return 0b0000000000000000;

    }
}

void print(unsigned int digit, unsigned int num, unsigned int pm){
    //Set latch to low (should be already)
      P1OUT &= ~LATCH;
      unsigned int i;
      unsigned int digitData;
      unsigned int numData;
      // If pm = 1; then we are drawing the PM dot
      if(pm == 1){
          digitData = 0;
          numData = 1;
          // Shift out the first 2 bits as zeros and the 3rd bit as a 1 (to indicate digit 9)
          P1OUT &= ~DATA;
          for(i = 0; i < 2; i++){
              pulseClock();
              }
          P1OUT |= DATA;
          pulseClock();
          }
      else{
          numData = getNum(num);
          digitData = getDigit(digit);
          // Shift out the first 3 bits as zeros (2 not connected to IV-18, and we're not drawing PM dot)
          P1OUT &= ~DATA;
          for(i = 0; i < 3; i++){
              pulseClock();
          }
      }
     // Shift out digit bits
     for(i=0; i<8; i++){
         pinWrite(DATA, (digitData & (1 << i)));
         pulseClock();
         }
     // Shift out the numner bits
     for(i=0; i<8; i++){
         pinWrite(DATA, (numData & (1 << i)));
         pulseClock();
         }
     // shift out one more NC bit
    P1OUT &= ~DATA;
    pulseClock();
    // Pulse the latch pin to write the values into the storage register
    P1OUT |= LATCH;
    P1OUT &= ~LATCH;
}