主程序：
#include <msp430f149.h>
#include<math.h>
float c,a=45;
int n=0;
long int b=300,cnt=0;
#define pi 3.14
#define CCR0_ini 500
#define keyin    (P2IN & 0xf0)
void delay(void)
{
    unsigned int tmp;
    for(tmp = 12000;tmp > 0;tmp--);
}

void creat_spwm(int av,float f);
int spwm[500];
 void TimerB_Init()
{
  P4DIR|=BIT1+BIT2+BIT3+BIT4+BIT5+BIT6;                            
// P4.1 - P4.6 output
  P4SEL |= BIT1+BIT2+BIT3+BIT4+BIT5+BIT6;
  TBCCR0 = CCR0_ini;                               
  TBCCTL1 = OUTMOD_2;
  TBCCTL4 = OUTMOD_6;
  TBCCR1=TBCCR4=spwm[n];
  TBCCTL2 = OUTMOD_2;                            
  TBCCTL5 = OUTMOD_6;
  TBCCR2=TBCCR5=spwm[n];
  TBCCTL3 = OUTMOD_2;
  TBCCTL6 = OUTMOD_6;
  TBCCR3=TBCCR6=spwm[n+(int)(c*2/3)];
  /*TBCCTL4 = OUTMOD_2;
  TBCCR4=spwm[n+53+53+53]*100;
  TBCCTL5 = OUTMOD_2;
  TBCCR5=spwm[n+53+53+53+53]*100;
  TBCCTL6 = OUTMOD_2;
  TBCCR6=spwm[n+53+53+53+53+53];*/
  TBCCTL0=CCIE;
  TBCTL = TBCLR + MC_1 + TBSSEL_2+TBIE;          
// clear TAR, up mode*/
}
/***********
av用来控制斩波时SPWM占空比,以达到控制电压输出的目的

av++可增大输出电压，av--可减小输出电压
c控制生成spwm时的点数，用来改变频率
4M/(CCR0*c)=Fsin
************/

void creat_spwm(int av,float f)
{
    int i;
    c=2800000/(CCR0_ini*f);
    //c*=2;
    for(i=0;i<c;i++)
    {
        spwm[i]=(int)((av/2)*(sin(2*pi *i/ c-pi/2)+1));
    }
}

void ini_sys(void)
{
    //WDTCTL=WDTPW+WDTHOLD;  //STOP W D T
    char i;
    BCSCTL1 &=~XT2OFF;//Set 430 clk  开启XT2，DOC的标称频率为最低 且不分频；XT1为低速晶体（32.768K）
  // BCSCTL2=SELM_2+SELS+DIVS_3;//选择MCLK SCLK的时钟源为高速时钟 不分频，均为8M
  BCSCTL2=SELM_2+SELS;
  do
  {
    IFG1&=~OFIFG;
    for(i=0xff;i>0;i--);
  }
  while ((IFG1&OFIFG)!=0);
}

void main()
{
   WDTCTL=WDTPW+WDTHOLD;
   ini_sys();
   creat_spwm(b,a);
   TimerB_Init();
  _EINT();
  //_BIS_SR(LPM0_bits + GIE);
  while(1);

}
#pragma vector=TIMERB0_VECTOR
__interrupt void TimerB(void)
{
  n=(n+1)%(int)c;
  TBCCR1=TBCCR4=spwm[n];
  TBCCR2=TBCCR5=spwm[n];
  TBCCR3=TBCCR6=spwm[(n+(int)(c*2/3))%(int)c];
  int temp;

if(keyin != 0xf0)       //键值有改变
        {
            delay();            //延时消抖
            if(keyin != 0xf0)   //再次检测按键状态
            {
                temp=keyin;

                while(keyin != 0xf0);   //等待按键被放开
                switch(temp)    //转换键值
                {
                case 0xe0:
                  creat_spwm(b,a++);
                  break;
                case 0xd0:
                  creat_spwm(b+=10,a);
                  break;
                  //a-=10;CCR0=a;CCR1=CCR2=a>>1;
                case 0xb0:
                            P2OUT = 0xfb;break;
                case 0x70:
                            P2OUT = 0xf7;break;
                default:
                            P2OUT = 0xff;break;
                }
                delay();delay();delay();delay();
                delay();delay();delay();delay();
            }
        }
}