gistfile1.c

/*
  Freeware. source [email protected]

  ADC pin:          P1.0
  PWM signal pin:   P1.2

  ADC signal is just a light sensor with a 1K resistor to 3.3V

*/

#include <msp430g2231.h>

#define pwmPin   0x04

volatile int ADCdata;
int inc = 1;
int ms_1 = 1100;
int motorDir = 550;
int isPulse = 0;

void main(void)
{
  WDTCTL = WDT_MDLY_8;                     // WDT ~8ms interval timer
  IE1 |= WDTIE;                             // Enable WDT interrupt
  
  ADC10CTL0 = ADC10SHT_2 + ADC10ON;         // sample and hold 16 cycles, ref on
  ADC10AE0 |= INCH_1;                       // P1.1 ADC option select
  ADC10DTC1 = 0x001;                        // 2 conversions
  
  P1DIR |= pwmPin;                          // P1.2 = output
  
  BCSCTL1 = CALBC1_1MHZ;	            // Running at 1 MHz
  DCOCTL = CALDCO_1MHZ;  
  
  TACTL = MC_0; // off

  while(1)
  {
    __bis_SR_register(LPM0_bits + GIE);     // LPM0, WDT_ISR will force exit
    
    if(isPulse)
    {
      isPulse = 0;
      P1OUT |= pwmPin;
      motorDir = (ADCdata - 150) * 3;
      TACCR0 = motorDir + ms_1;
      TACTL = TASSEL_2 + MC_1 + TAIE + TACLR + OUT;       // ACLK, upmode, interrupt enabled 
      TACCTL0 |= CCIE;  
    }
    else
    {
      isPulse = 1;
      ADC10SA = (unsigned int)&ADCdata;         // store data here  
      ADC10CTL0 |= ENC + ADC10SC;           // Start sampling
    }
  }
}

#pragma vector = TIMERA0_VECTOR
__interrupt void CCR0_ISR(void) 
{
  //TACCTL0 &= ~CCIE; 
  TACTL = MC_0;                             // timer A off, interrupt disabled 
  P1OUT &= ~pwmPin; 
}

#pragma vector = WDT_VECTOR
__interrupt void WDT_ISR(void)
{
  __bic_SR_register_on_exit(LPM0_bits);     // Exit LPM0
}