msp430fr5969 利用定时器触发ad采样问题，急急！！

/*******************************************************************************
** Function : msp430_timerA0_init                                             **
** Descrpt  :                                                                 **
** Input    :                                                                 **
** Output   :                                                                 **
** Return   :                                                                 **
================================================================================
** Author : Triton Zhang                                                      **
** Date   : May.03,2015                                                       **
*******************************************************************************/
void msp430_timerA0_init(void)
{
    // TA0 UP模式,1MS 中断
    TA0CCR0 = TA0CCR0_VAL;                      // PWM Period              //by slf 2015/11/30 modified adc
    TA0CCR1 = TA0CCR1_VAL;                      // TACCR1 PWM Duty Cycle    //by slf 2015/11/30 modified adc
   
    TA0CCTL1 = OUTMOD_7;                        // TACCR1 set/reset
    TA0CTL = TASSEL__ACLK | MC__UP | TACLR;     // ACLK, up mode
}

/*******************************************************************************
** Function : msp430f_adc12_init                                              **
** Descrpt  :                                                                 **
** Input    :                                                                 **
** Output   :                                                                 **
** Return   :                                                                 **
================================================================================
** Author : Triton Zhang                                                      **
** Date   : May.03,2015                                                       **
*******************************************************************************/
void msp430_adc12b_init(void)
{
    PORT_ADC_SEL0 |= (ADC_PIN0 + ADC_PIN1 + ADC_PIN2 + ADC_PIN3);  
    PORT_ADC_SEL1 |= (ADC_PIN0 + ADC_PIN1 + ADC_PIN2 + ADC_PIN3);
   
    ADC12CTL2 = ADC12RES_2 + ADC12PWRMD;   // 12-bit conversion results, low power mode
}
/*******************************************************************************
** Function : board_current_adc_init                                          **
** Descrpt  :                                                                 **
** Input    :                                                                 **
** Output   :                                                                 **
** Return   :                                                                 **
================================================================================
** Author : Triton Zhang                                                      **
** Date   : May.03,2015                                                       **
*******************************************************************************/
void board_current_adc_init(uint8_t nMode)
{
    PORT_ADC_SEL0 |= (ADC_PIN0 + ADC_PIN1 + ADC_PIN2 + ADC_PIN3);  
    PORT_ADC_SEL1 |= (ADC_PIN0 + ADC_PIN1 + ADC_PIN2 + ADC_PIN3);  
   
    msp430_adc_sample();
    msp430_dma0_init(ADC_GROUP_NUM);    // by slf 2015/11/30 modified adc
    msp430_timerA0_init();
}

uint8_t msp430_adc_sample(uint8_t Mod)
{
    uint8_t i = 0;
    uint8_t timeout = 24;
       
    ADC12CTL0 &= ~ADC12ENC;
    ADC12CTL0 &= ~ADC12ON;
    __delay_cycles(10);
   
    ADC12CTL0 = ADC12SHT0_2 | ADC12SHT1_2| ADC12ON;
    ADC12CTL1 = ADC12SHP | ADC12CONSEQ_2 | ADC12SHS_1; //|;      // Timer TA0 Trigger ADC
    ADC12CTL2 = ADC12RES_2 + ADC12PWRMD;                    // 12-bit conversion results, low power mode
    ADC12CTL3 = 0;

    ADC12MCTL0 = ADC_CHN[3];
    ADC12CTL0 |= ADC12ENC | ADC12SC;                        // Start sampling/conversion

    return 1;
}