#include <msp430.h> 

void ClockInit()
{//最终MCLK:16MHZ,SMCLK:8MHZ,ACLK:32KHZ
     UCSCTL6 &= ~XT1OFF;          //启动XT1
     P5SEL |= BIT2 + BIT3;        //XT2引脚功能选择
     UCSCTL6 &= ~XT2OFF;          //打开XT2
     __bis_SR_register(SCG0);
     UCSCTL0 = DCO0+DCO1+DCO2+DCO3+DCO4;
     UCSCTL1 = DCORSEL_4;       //DCO频率范围在28.2MHZ以下
     UCSCTL2 = FLLD_5 + 1;       //D=16，N=1
     //n=8,FLLREFCLK时钟源为XT2CLK；DCOCLK=D*(N+1)*(FLLREFCLK/n);DCOCLKDIV=(N+1)*(FLLREFCLK/n);
     UCSCTL3 = SELREF_5 + FLLREFDIV_3;
     //ACLK的时钟源为DCOCLKDIV,MCLK\SMCLK的时钟源为DCOCLK
     UCSCTL4 = SELA_4 + SELS_3 +SELM_3;
     //ACLK由DCOCLKDIV的32分频得到，SMCLK由DCOCLK的2分频得到
     UCSCTL5 = DIVA_5 +DIVS_1;
}

void IO_Init(void)
{
    P8DIR |= BIT1;                          // 设置P8.1口为输出模式  控制LED灯
    P3DIR |= BIT7;                         
    P3DIR |= BIT6;                          // 设置P3.6口为输出模式  控制蜂鸣器
    P1DIR |= BIT0;                         
    P1OUT |= BIT0;
    P1DIR |= BIT2;    // P1.2 方向为输出
    P1SEL |= BIT2;    // P1.2端口为外设，定时器TA0.1

    P2OUT |= BIT3+BIT6;                     
    P2REN |= BIT3+BIT6;                     
    P1REN = BIT3+BIT2;                      
    P1OUT |= BIT3+BIT2;                     
}
int iflag=0;
int main(void)
{
    unsigned int Period=512;            //PWM Period  CCR0
    unsigned int duty=0;                //PWM duty cycle (%)
    WDTCTL = WDTPW | WDTHOLD;           // Stop watchdog timer
    ClockInit();
    IO_Init();

    TA0CTL = MC_1 + TASSEL_2 + TACLR ;  // SMCLK(8M), up mode, clear TAR
    TA0CCR0 =Period;                    // PWM Period
    TA0CCTL1 = OUTMOD_7;                // CCR1 toggle/set
    TA0CCR1 = duty ;                    // CCR1 PWM duty cycle  0

    __no_operation();                         // For debugger
    __delay_cycles(16000000*2);
    while(1)
    {
        if(iflag==0)
        {
            duty += 1;
        }
        if(duty>=512)
        {
            iflag = 1;
        }
        if(iflag==1)
        {
            duty -= 1;
        }
        if(duty==0)
        {
            iflag=0;
        }

        TA0CCR1 = duty;
        __delay_cycles(16000000*0.005);
    }
}