atividade10.c

#include <msp430.h>
#include <intrinsics.h>

#define BTN     BIT1    // Port 1.1
#define LED    BIT0    // Port 1.0

volatile int n = 0;

/**
 * main.c
 */

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer

    P1DIR &= ~BTN;

    P1OUT |= BTN; // btn pulled up
    P1REN |= BTN; // pull up resistor enabled

    P1IE = BTN;
    P1IES = BTN; // high to low transition

    P1SEL = BIT4; // enable timerA output on 1.4...
    P1DIR |= BIT4; // ...as output

    TA0CTL = TASSEL_1 | ID_0 | MC_1 | TACLR;
    TA0CCR0 = 326;
    TA0CCR3 = 0;
    TA0CCTL3 = OUTMOD_7;


    __enable_interrupt();
    while(1){}
}

#pragma vector = PORT1_VECTOR
__interrupt void P1_ISR(void) {
    switch(P1IV) {
    case P1IV_P1IFG1:
        if(n >= 326)
            n = 0;
        else {
            TA0CCR3 = n;
            n += 3;
        }
        break;
    }
}