CCS/TMS320F280049: When debugging FLASH erase, enter illegal interrupt problem.

Tool/software: Code Composer Studio

Hi，

Compiler:Code Composer Studio 9.0.1.

When debugging FLASH erase, enter illegal interrupt problem.

• The erase FLASH program is performed as follows:

void vErase()

{

//.....omit

NOP;
NOP;
Boot_FlashErase();

//....omit

}

#pragma CODE_SECTION(Boot_FlashErase, ".TI.ramfunc");
void Boot_FlashErase(void)
{
  uint32 u32Index = 0;
  uint16 i = 0;
  Fapi_StatusType oReturnCheck;
  Fapi_FlashStatusType oFlashStatus;
  Fapi_FlashStatusWordType oFlashStatusWord;
  //EALLOW;

oReturnCheck = Fapi_initializeAPI(F021_CPU0_BASE_ADDRESS, 100);

if(oReturnCheck != Fapi_Status_Success)
{

// Check Flash API documentation for possible errors
Example_Error(oReturnCheck);
}

oReturnCheck = Fapi_setActiveFlashBank(Fapi_FlashBank0);

// Check Flash API documentation for possible errors

if(oReturnCheck == Fapi_Status_Success)
{
  for(i = 0; i < EraseSectorNum; i++)
  {
  // Erase Flash Bank0 sector6
  oReturnCheck = Fapi_issueAsyncCommandWithAddress(Fapi_EraseSector,
  (uint32 *)(Bzero_Sector5_start + 0x1000 * i));

  // Wait until FSM is done with erase sector operation
  while (Fapi_checkFsmForReady() != Fapi_Status_FsmReady){}

  /* if(oReturnCheck != Fapi_Status_Success)
  {
   // Check Flash API documentation for possible errors
   Example_Error(oReturnCheck);
   }*/
  }

}

// Read FMSTAT register contents to know the status of FSM after
// erase command to see if there are any erase operation related errors
oFlashStatus = Fapi_getFsmStatus();
if(oFlashStatus != 0)
{
FMSTAT_Fail();
}

// Do blank check
// Verify that Bank0 sector6 is erased. The Erase command itself does a verify as
// it goes. Hence erase verify by CPU reads (Fapi_doBlankCheck()) is optional.
/* oReturnCheck = Fapi_doBlankCheck((uint32 *)Bzero_Sector15_start,
Sector8KB_u32length,
&oFlashStatusWord);

if(oReturnCheck != Fapi_Status_Success)
{
// Check Flash API documentation for error info
Example_Error(oReturnCheck);
}*/

}

• When I add one more NOP function to the vErase function, the program execution wipes FLASH with no problem.as follows:

void vErase()

{

//.....omit

NOP;
NOP;
NOP;

Boot_FlashErase();

//....omit

}

• Question：

1. Why does initializing the API function to perform erasing FLASH enter an illegal interrupt？
2. Why is it ok to add one more NOP statement to the program？
3. Adding empty statements only increases storage space. Why does it affect API function execution?