#include <msp430.h>


/**
 * main.c
 */

int main(void)
{
    WDTCTL = WDTPW + WDTHOLD;   // stop watchdog timer
    //step 1. to 3.
    UCSCTL3 = SELREF__REFOCLK;           /*1.p1 set FLL ref to REF0CLK */
    UCSCTL4 |= SELA__REFOCLK;              /*2.p1 Set ACLK = REFOCLK */
    UCSCTL0 = 0x0000;                      /*3.p1 set lowest DCOx and MODx bits */

    do
    {
        //step 4. and 5.
        UCSCTL7 &= ~(XT2OFFG + XT1LFOFFG + DCOFFG); /*4.p1 Clear XT2,XT1,DCO fault flags */
        SFRIFG1 &= ~OFIFG;                          /*5.p1 Clear fault flags */

    }while(SFRIFG1&OFIFG);  /*6.p1 test the oscillator fault flag */

    __bis_SR_register(SCG0); //disable the FLL control loop

    //step 7. and 8.
    UCSCTL1 =  DCORSEL_6;             /*7.p1 set DCO Multiplier for 8MHz*/
    UCSCTL2 &= 0xFE00;
    UCSCTL2 |= 0xF3;           /*8.p1 Set DCO Multiplier for 8MHz */
                                      // (N + 1) * FLLRef = Fdco
                                      // (243 + 1) * 32768 = 8MHz

    __bic_SR_register(SCG0); //enable the FLL control loop

    __delay_cycles(250000);  //settling time for the DCO

    //step 9.p1

    P7DIR |= BIT7;           /*9.p1 P7.7 = toggle */
    P7SEL |= BIT7;


    //Steps 1. to 4.
    TA0CCTL0 = CCIE;                            /*1.p2 allow interrupt activate CCIE flag */
    TA0CCR0 = 1600 - 1 ;                        /*2.p2 set up TA0CCR0 to the value it activate */
    TA0CTL = TASSEL_2 + MC_1 + TACLR ;//+ ID_1;    /*3.p2 SMCLK in MC "up" mode, set TACLR flag (start timer)  */

    P1DIR |= BIT0;                               /*4.p2 activate pin p1.0 and set it to output mode */
    P1OUT &= ~BIT0;

    __bis_SR_register(LPM0_bits + GIE);
    __no_operation();
}

#pragma vector = TIMER0_A0_VECTOR
__interrupt void TIMER0_A0_ISR(void){
    P1OUT ^= BIT0;                               /*5.p2 Toggle the LED in the interrupt service routine */
}