#include <signal.h>
#include <msp430x20x3.h>

volatile unsigned long timerA_tick_count = 0;
volatile unsigned int pwm0, pwm1;

interrupt(TIMERA0_VECTOR)
wewtimer_isr0()
{
    TA0CCR0 = 0xFFFF;		/* set at overflow */
    TA0CCTL0 = OUTMOD_SET;	/* note: don't interrupt */
}

interrupt(TIMERA1_VECTOR)
wewtimer_isr()
{
    timerA_tick_count++;
    switch (TA0IV) { 				/* reset intrerupt */
    
    case TAIV_OVERFLOW:
	TA0R += 65535-8000;			/* count another ms */
	/*
	 * Note that at this point, both CC units should have SET
	 * their respective output bits when TAR hit 0xFFFF
	 */
	TA0CCTL0 = OUTMOD_RESET + CCIE;		/* reset and int at count */
	TA0CCR0 = pwm0;				/* set new count */
	TA0CCTL1 = OUTMOD_RESET + CCIE;
	TA0CCR1 = pwm1;
	break;

    case TAIV_CCR1:
	TA0CCR1 = 0xFFFF;		/* set at overflow */
	TA0CCTL1 = OUTMOD_SET;		/* note: don't interrupt */
	break;
    }
}

void delay(unsigned long ms)
{
    unsigned long start = timerA_tick_count;
	
    while (timerA_tick_count - start <= ms) ; // spin.
}

void main() {

    int i;
    /*
     * Change clock to approx 8MHz (prescaled from internal 1.1MHz
     */
    BCSCTL1 = CALBC1_8MHZ;                    // Set range
    DCOCTL = CALDCO_8MHZ;                     // Set DCO step + modulation */

    /*
     * set up pin 6 as timer PWM output
     */
    P2SEL = 0;				/* use port2 pins as outputs */
    P1SEL |= 1<<6;			// TA0CCR1 output on pin 6
    P1DIR |= 1<<6;

    /*
     * Set up timer A
     */
    TA0CTL = TASSEL_SMCLK + MC_CONT + TAIE;	/* SMCLK, continuous mode */
    TA0R = 65536-8000;			/*  initial value */
    TA0CCTL1 = OUTMOD_RESET+CCIE;	// timer outputing PWM
    TA0CCTL0 = OUTMOD_RESET+CCIE;	// timer outputing PWM
    eint();				/* global interrupts on */

/*********************************************
 * the big question.  Does changing TA0CCR0 change the behavior of TA0CCTL1 ?
 *********************************************/
    TA0CCR0 = pwm0 = 65536-4000;	/* 50% while we test pwm1 */

    while (1) {
	for (i=100; i < 8000; i += 50) {
	    TA0CCR1 = pwm1 = (65535-8000)+i;
	    delay(100);
	}
    }
}