想用MSP430G2553控制DAC0800输出扫频信号，256个采样点，扫频范围10～2000Hz，结果不输出波形，不知道哪里有问题，求各位前辈指教。代码如下：
#include <msp430.h>
#include "stdint.h"
static uint16_t f = 10;
static uint16_t interval =0 ;
const uint16_t temp[256]={
      0x7F,0x82,0x85,0x88,0x8B,0x8F,0x92,0x95,0x98,0x9B,0x9E,0xA1,0xA4,0xA7,0xAA,0xAD
      ,0xB0,0xB3,0xB6,0xB8,0xBB,0xBE,0xC1,0xC3,0xC6,0xC8,0xCB,0xCD,0xD0,0xD2,0xD5,0xD7
      ,0xD9,0xDB,0xDD,0xE0,0xE2,0xE4,0xE5,0xE7,0xE9,0xEB,0xEC,0xEE,0xEF,0xF1,0xF2,0xF4
      ,0xF5,0xF6,0xF7,0xF8,0xF9,0xFA,0xFB,0xFB,0xFC,0xFD,0xFD,0xFE,0xFE,0xFE,0xFE,0xFE
      ,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFD,0xFD,0xFC,0xFB,0xFB,0xFA,0xF9,0xF8,0xF7,0xF6
      ,0xF5,0xF4,0xF2,0xF1,0xEF,0xEE,0xEC,0xEB,0xE9,0xE7,0xE5,0xE4,0xE2,0xE0,0xDD,0xDB
      ,0xD9,0xD7,0xD5,0xD2,0xD0,0xCD,0xCB,0xC8,0xC6,0xC3,0xC1,0xBE,0xBB,0xB8,0xB6,0xB3
      ,0xB0,0xAD,0xAA,0xA7,0xA4,0xA1,0x9E,0x9B,0x98,0x95,0x92,0x8F,0x8B,0x88,0x85,0x82
      ,0x7F,0x7C,0x79,0x76,0x73,0x6F,0x6C,0x69,0x66,0x63,0x60,0x5D,0x5A,0x57,0x54,0x51
      ,0x4E,0x4B,0x48,0x46,0x43,0x40,0x3D,0x3B,0x38,0x36,0x33,0x31,0x2E,0x2C,0x29,0x27
      ,0x25,0x23,0x21,0x1E,0x1C,0x1A,0x19,0x17,0x15,0x13,0x12,0x10,0x0F,0x0D,0x0C,0x0A
      ,0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x03,0x02,0x01,0x01,0x00,0x00,0x00,0x00,0x00
      ,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x02,0x03,0x03,0x04,0x05,0x06,0x07,0x08
      ,0x09,0x0A,0x0C,0x0D,0x0F,0x10,0x12,0x13,0x15,0x17,0x19,0x1A,0x1C,0x1E,0x21,0x23
      ,0x25,0x27,0x29,0x2C,0x2E,0x31,0x33,0x36,0x38,0x3B,0x3D,0x40,0x43,0x46,0x48,0x4B
      ,0x4E,0x51,0x54,0x57,0x5A,0x5D,0x60,0x63,0x66,0x69,0x6C,0x6F,0x73,0x76,0x79,0x7C};

/*
* main.c
*/
int main(void) {
    WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer
    /*配置DCO为8MHz*/
    DCOCTL = CALDCO_8MHZ;
    BCSCTL1 = CALBC1_8MHZ;
    BCSCTL2 &= ~SELS;  //配置SMCLK的时钟源为DCO
    BCSCTL2 &= ~(DIVS0 | DIVS1);   //SMCLK的分频系数置为1
    uint16_t j = 0;
    uint16_t k = 0;
    interval = (int)8000000 / (f * 256) - 1 ;
    P1DIR = 0xFF ;
    TA1CTL |= TASSEL_2;  //设置时钟源为SMCLK
    TA1CTL |= MC_1;      //工作模式为向上计数模式
    TA1CCR0 = 49999;     //每0.05s改变一次正弦波频率
    TA1CTL |= TAIE;   //打开TAIFG中断
    __bis_SR_register(GIE);   //打开全局中断
    while(1)
    {
     for(j=0 ; j < interval;j++);
     P1OUT=temp[k];
     k++;
     if(k >= 256) k=0;
    }

}
#pragma vector=TIMER1_A1_VECTOR
__interrupt void Timer1_A1(void)
{
switch(TA1IV)   //判断是哪个标志源产生了中断
  {
  case 0x02:
   break;
  case 0x04:
   break;
  case 0x0A:
   f=f+10;
   if(f>=2000) f=10;
   interval = 8000000 / (f * 256) - 1 ;
   break;
  default:
   break;
  }
}