DSP2812 改变PWM输出方式出现窄脉冲问题

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各位大虾，问题如题所示。具体内容如下：
本人欲用DSP2812实现非对称PWM发波，其中定时器为增计数方式。在第一个周期PWM输出高有效，下一个周期PWM输出低有效，通过更改比较操作控制寄存器ACTRA实现。如此交替进行。但是在PWM输出方式更改时刻出现窄脉冲，不知是DSP本身的缺陷还是我设置问题？
PWM输出设置如下：

      EALLOW;                                                          // Enable EALLOW
      GpioMuxRegs.GPAMUX.all |= 0xE03F;                      // Setting PWM1-6 & C123TRIP
      EDIS;                                                       // Disable EALLOW

      EvaRegs.T1PR = p->PERIOD;                               // Init Timer 1 period Register
      EvaRegs.T1CON.all       = EVPMSM_T1CON;                   // Symmetrical Operation,soft stop mode
      EvaRegs.DBTCONA.all = EVPMSM_DBTCONA;                // Init DBTCONA Register
      EvaRegs.ACTRA.all       = EVPMSM_ACTRA_HIGHEN;       // Init ACTRA Register
      EvaRegs.EXTCONA.bit.INDCOE =1;             // Independent compare output enable mode is enabled
      EvaRegs.COMCONA.all = 0x82E0;                   // Init COMCONA Register: 1010 0110 1110 0111
      EvaRegs.CMPR1 = p->CMPRA;                         // Init CMPR1 Register
      EvaRegs.CMPR2 = p->CMPRB;                         // Init CMPR2 Register
      EvaRegs.CMPR3 = p->CMPRC;                         // Init CMPR3 Register
      EvaRegs.ACTRA.all       = EVPMSM_ACTRA_STOP;       //

#define EVPMSM_T1CON             (       FREE_RUN_FLAG +
                                                   TIMER_CONT_UP +
                                          TIMER_CLK_PRESCALE_X_8 +
                                    TIMER_ENABLE_BY_OWN +
                                    TIMER_ENABLE)
#define EVPMSM_ACTRA_HIGHEN       (       COMPARE1_AH +
                                    COMPARE2_AL +
                                       COMPARE3_AH +
                                       COMPARE4_AL +
                                       COMPARE5_AH +
                                       COMPARE6_AL )
#define EVPMSM_ACTRA_LOWEN       (       COMPARE1_AL +
                                    COMPARE2_AH +
                                       COMPARE3_AL +
                                       COMPARE4_AH +
                                       COMPARE5_AL +
                                       COMPARE6_AH )