IRSensor (ADC demo)

/*
 * IRProximitySensor by James Trimble, Capt, USAF
 * USAFA ECE Automata Club
 * Description: Uses the Analog-to-Digital Converter to read the voltage from an IR Proximity
 * Sensor circuit and then turns on 0,1, or 2 on-board LEDs based on the reading.
 */

#include <msp430.h> 

int main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                   // Stop WDT
  ADC10CTL0 = ADC10SHT_3 + ADC10ON + ADC10IE; // ADC10ON, interrupt enabled
  ADC10CTL0 &= ~0xD000;			      // Use GND to VCC as the reference range
  ADC10CTL1 = INCH_4;                         // input A4
  ADC10AE0 |= BIT4;                           // PA.1 ADC option select
  ADC10CTL1 |= ADC10SSEL1|ADC10SSEL0;         // Select SMCLK
  P1DIR |= 0x41;                              // Set P1.0 & P1.6 to output direction


  for (;;)
  {
	ADC10CTL0 |= ENC + ADC10SC;               // Sampling and conversion start
	__bis_SR_register(CPUOFF + GIE);          // LPM0, ADC10_ISR will force exit
	if (ADC10MEM > 0x3FC)
	  P1OUT |= 0x41;			  // Set P1.0 and P1.6 LEDs (on)
	else if (ADC10MEM > 0x3F9)
	  P1OUT |= 0x01;                          // Set P1.0 LED (on)
	else if (ADC10MEM > 0x3F6)
	  P1OUT |= 0x40;			  // Set P1.6 LED (on);
	else
	  P1OUT &= ~0x41;                         // Clear P1.0 and P1.6 LEDs (off)
  }

  return 0;
}

// ADC10 interrupt service routine
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
  __bic_SR_register_on_exit(CPUOFF);          // Clear CPUOFF bit from 0(SR)
}

I'll be updating this to make it more readable.