HRPWM SFO（）函数输出问题

使用如下TI提供的部分程序

status = SFO_INCOMPLETE;

while (status == SFO_INCOMPLETE)// Call until complete   

{   status = SFO();  }

if(status!=SFO_ERROR)// IF SFO() is complete with no errors   

{   EALLOW;   EPwm1Regs.HRMSTEP=MEP_ScaleFactor;   EPwm2Regs.HRMSTEP=MEP_ScaleFactor;   EDIS;  }

if (status == SFO_ERROR)  {  while(1);

                                               // SFO function returns 2 if an error occurs          

                                              // The code would loop here for infinity if it         

                                                  // returns an error  }  //

SFO()函数总是返回数值2，也就是SFO_ERROR，导致最后进入死循环，请问下这是什么原因