TMS320F28035: COMP比较器

看上面图应该是在COMPSTS置1处，RAMPSTS会载入RAMPMAXREF值，但是调试的现象是COMP置1后，RAMPSTS会保持计数到的值不变，到下一个PWMSYNC到来之后继续计数，

    EALLOW;
    // 比较器和DAC使能；
    Comp1Regs.COMPCTL.bit.COMPDACEN = 1;

    Comp1Regs.RAMPMAXREF_SHDW = 0xfff0;
    Comp1Regs.RAMPDECVAL_SHDW = 0x0100;

    // 0:COMP-链接内部DAC模块  1:链接外部引脚
    Comp1Regs.COMPCTL.bit.COMPSOURCE = 0;

    // 1:内部DAC:由 RAMPSTS 寄存器控制；  0：DAC由 DACVAL 寄存器控制
    Comp1Regs.DACCTL.bit.DACSOURCE = 1;

    //PWMSYNC1 is the source sync    RAMPSOURCE+1
    Comp1Regs.DACCTL.bit.RAMPSOURCE = 0;

    Comp1Regs.DACCTL.bit.FREE_SOFT =0;

    // Synchronized value of comparator is passed through
    Comp1Regs.COMPCTL.bit.QUALSEL = 5;

    //0:Asynchronous version of Comparator output is passed
    //1:Synchronous version of Comparator output is passed
    Comp1Regs.COMPCTL.bit.SYNCSEL=0;

    // 输出信号反转；COMP+>COMP-,输出高电平；反之，输出低；
    Comp1Regs.COMPCTL.bit.CMPINV = 0;

    EDIS;

希望大佬帮忙给看看是哪配置的问题