Temperature LED demo version 2

This is my second Temperature demo using LED's, this time driven by the 74hc595 8-bit shift register.

Examples in this demo:

1. Using the 74hc595 to drive a LED.

2. LED truth table for selecting digits.

3. Multiplexing digits

4. Binary to decimal conversion.

Code:

//  MSP430G2231  internal temp senser read
// and display on 7 segment display via two 74hc595 shift registers
#include  <msp430x20x2.h>
#include <io.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
int ledtable[10] = { 0x7e, 0x30, 0x6d, 0x79, 0x33, 0x5b, 0x5f, 0x70, 0x7f, 0x7b };
void Initializeports(void);
void ConfigureAdcTempSensor(void);
static void __inline__delay(register unsigned int n);
int display_led(int t, int display);
long tempMeasured[8];
unsigned char tempMeasuredPosition=0;
long tempAverage,tempAverage2;
long tempCalibrated, tempDifference;
void main(void)
{
  unsigned char i;
  int tc = 0, msd, lsd, r1, r2, r3, r4, t, alt_digit = 0;
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  
  Initializeports();
  ConfigureAdcTempSensor();
  
  __enable_interrupt();                     // Enable interrupts.
  /* Main Application Loop */
  while(1)
  {
    ADC10CTL0 |= ENC + ADC10SC;             // Sampling and conversion start
    __bis_SR_register(CPUOFF + GIE);        // LPM0 with interrupts enabled
    /* Moving average filter out of 8 values to somewhat stabilize sampled ADC */
    tempMeasured[tempMeasuredPosition++] = ADC10MEM;
    if (tempMeasuredPosition == 8)
      tempMeasuredPosition = 0;
    tempAverage2 = 0;
    for (i = 0; i < 8; i++)
      tempAverage2 += tempMeasured[i];
    tempAverage2 >>= 3; // Divide by 8 to get average
    tempAverage=tempAverage2; //use temporary avarage to prevent ISRs from using intermediate values
    tc++;
    if (tc > 2000) 
       {

t = ((tempAverage - 630) * 761) / 1024 ;

tc = 0;

       }

r2 = t / 10; //Binary to Decimal conversion for two digits.

      r1 = t - r2 * 10;
msd = r2;
lsd = r1;

if (alt_digit == 0 )

{

display_led( msd, 0 );

alt_digit = 1;

}else{

display_led( lsd, 1 );

alt_digit = 0;

     }

  }
}
int display_led(int t, int display)
{
int j, i;
if (display == 0 )
   { 
   j = (ledtable[t]<<1) | 0x0200;
   }
   
if (display == 1 )
   {
   j = (ledtable[t]<<1) | 0x0100;
   }
P1OUT &= ~BIT2;
for(i=0; i < 10; i++)
   {    
   P1OUT &= ~BIT1;
   if  (j & 0x200)
      {
      P1OUT |= BIT0;
      }else{
      P1OUT &= ~BIT0;
      }
P1OUT |= BIT1;
   j = j<<1;
   }
P1OUT |= BIT2;
}
void Initializeports(void)
{
P1DIR |= 0x07; 
P1SEL = 0x00;
}


void ConfigureAdcTempSensor(void)
{
  unsigned int i;
  /* Configure ADC Temp Sensor Channel */
  ADC10CTL1 = INCH_10 + ADC10DIV_3;         // Temp Sensor ADC10CLK/4
  ADC10CTL0 = SREF_1 + ADC10SHT_3 + REFON + ADC10ON + ADC10IE;
  __inline__delay(0x1000);                     // Wait for ADC Ref to settle
  ADC10CTL0 |= ENC + ADC10SC;               // Sampling and conversion start
  __bis_SR_register(CPUOFF + GIE);          // LPM0 with interrupts enabled
  tempCalibrated = ADC10MEM;
  for (i=0; i < 8; i++)
    tempMeasured[i] = tempCalibrated;
  tempAverage = tempCalibrated;
}
// Delay Routine from mspgcc help file
static void __inline__delay(register unsigned int n)
{
  __asm__ __volatile__ (
  "1: \n"
  " dec %[n] \n"
  " jne 1b \n"
        : [n] "+r"(n));
}
// ADC10 interrupt service routine
interrupt(ADC10_VECTOR) ADC10_ISR (void)
{
  __bic_SR_register_on_exit(CPUOFF);        // Return to active mode
}