How to enable/disable Flash Write Protection?

[Junde]

Hi guys,

I am read the example "STM32Cube_FW_F1_V1.8.4\Projects\STM32F103RB-Nucleo\Examples\FLASH\FLASH_WriteProtection", and want to rewrite it on my board.

my code is as follows:

  HAL_FLASH_Unlock();
  HAL_FLASH_OB_Unlock();
  
  HAL_FLASHEx_OBGetConfig(&OptionsBytesStruct);
  LOG_DBG("current config: WRPState[%d]\n", OptionsBytesStruct.WRPState);
  LOG_DBG("current config: WRPPage[0x%08x]\n", OptionsBytesStruct.WRPPage);
  if((OptionsBytesStruct.WRPPage & FLASH_PAGE_TO_BE_PROTECTED) == FLASH_PAGE_TO_BE_PROTECTED) { // if WRP enable
      LOG_DBG("Flash is WriteProtection\n");
      OptionsBytesStruct.OptionType = OPTIONBYTE_WRP;
      OptionsBytesStruct.WRPState = OB_WRPSTATE_DISABLE;
      OptionsBytesStruct.WRPPage = FLASH_PAGE_TO_BE_PROTECTED;
      if(HAL_FLASHEx_OBProgram(&OptionsBytesStruct) != HAL_OK) {
          LOG_ERR("Flash OB program err when turn WRP off\n");
      }
      HAL_Delay(10000);
      LOG_DBG("system reset\n");
      HAL_Delay(1000);
      HAL_FLASH_OB_Launch();
} else {
      LOG_DBG("Flash is NOT WriteProtection\n");
      OptionsBytesStruct.OptionType = OPTIONBYTE_WRP;
      OptionsBytesStruct.WRPState = OB_WRPSTATE_ENABLE;
      OptionsBytesStruct.WRPPage = FLASH_PAGE_TO_BE_PROTECTED;
      if(HAL_FLASHEx_OBProgram(&OptionsBytesStruct) != HAL_OK) {
          LOG_ERR("Flash OB program err when turn WRP on\n");
      }
      HAL_Delay(10000);
      LOG_DBG("system reset\n");
      HAL_Delay(1000);
      HAL_FLASH_OB_Launch();
  }

  HAL_FLASH_OB_Lock();
  HAL_FLASH_Lock();

The output is as this:

Flash Write Protection demo...
current config: WRPState[0]
current config: WRPPage[0xFFFFFFFF]
Flash is WriteProtection
system reset

Flash Write Protection demo...
current config: WRPState[0]
current config: WRPPage[0xFFFFFFFF]
Flash is WriteProtection
system reset

Flash Write Protection demo...
current config: WRPState[0]
current config: WRPPage[0xFFFFFFFF]
Flash is WriteProtection
system reset

What I expected of the output should be like "WRP_EN --> WRP_DIS -->WRP_EN --> WRP_DIS ......".

I have no idea what I was wrong, help me, please. 

Thank you.

BTW, I am confused about the result of "HAL_FLASHEx_OBGetConfig(&OBStruct);", if the result as below:

  HAL_FLASHEx_OBGetConfig(&OptionsBytesStruct);
  LOG_DBG("current config: WRPState[%d]\n", OptionsBytesStruct.WRPState);   // 0
  LOG_DBG("current config: WRPPage[0x%08x]\n", OptionsBytesStruct.WRPPage); // 0xFFFFFFFF

Then, does that mean all the flash is WRP, or all the flash is NOT in WRP?

Thanks again for your help in advance.

[FBL · Accepted solution]

Hello @Junde 

Referring to PM0068, you can check write protection definition (0 for activated WRP). 

[Junde]

@FBL Thanks for your help.

I was wrong about the meaning of the FLASH_WRPR bit.(0 is for active, NOT 1)

So my code should be as this:

  HAL_FLASH_Unlock();
  HAL_FLASH_OB_Unlock();
  
  HAL_FLASHEx_OBGetConfig(&OptionsBytesStruct);
  LOG_DBG("current config: WRPState[%d]\n", OptionsBytesStruct.WRPState);
  LOG_DBG("current config: WRPPage[0x%08x]\n", OptionsBytesStruct.WRPPage);
  if((~OptionsBytesStruct.WRPPage & FLASH_PAGE_TO_BE_PROTECTED) == FLASH_PAGE_TO_BE_PROTECTED) { // if WRP enable
      LOG_DBG("Flash is WriteProtection\n");
      OptionsBytesStruct.OptionType = OPTIONBYTE_WRP;
      OptionsBytesStruct.WRPState = OB_WRPSTATE_DISABLE;
      OptionsBytesStruct.WRPPage = FLASH_PAGE_TO_BE_PROTECTED;
      if(HAL_FLASHEx_OBProgram(&OptionsBytesStruct) != HAL_OK) {
          LOG_ERR("Flash OB program err when turn WRP off\n");
      }
      HAL_Delay(10000);
      LOG_DBG("system reset\n");
      HAL_Delay(1000);
      HAL_FLASH_OB_Launch();
} else {
      LOG_DBG("Flash is NOT WriteProtection\n");
      OptionsBytesStruct.OptionType = OPTIONBYTE_WRP;
      OptionsBytesStruct.WRPState = OB_WRPSTATE_ENABLE;
      OptionsBytesStruct.WRPPage = FLASH_PAGE_TO_BE_PROTECTED;
      if(HAL_FLASHEx_OBProgram(&OptionsBytesStruct) != HAL_OK) {
          LOG_ERR("Flash OB program err when turn WRP on\n");
      }
      HAL_Delay(10000);
      LOG_DBG("system reset\n");
      HAL_Delay(1000);
      HAL_FLASH_OB_Launch();
  }

  HAL_FLASH_OB_Lock();
  HAL_FLASH_Lock();

[Georgy Moshkin]

Checking WRPState is useless, because this field is never set in HAL_FLASHEx_OBGetConfig() function:

void HAL_FLASHEx_OBGetConfig(FLASH_OBProgramInitTypeDef *pOBInit)
{
  pOBInit->OptionType = OPTIONBYTE_WRP | OPTIONBYTE_RDP | OPTIONBYTE_USER;

  /*Get WRP*/
  pOBInit->WRPPage = FLASH_OB_GetWRP();

  /*Get RDP Level*/
  pOBInit->RDPLevel = FLASH_OB_GetRDP();

  /*Get USER*/
  pOBInit->USERConfig = FLASH_OB_GetUser();

  /* WRPState was never set! */
}

You can only rely on WRPPage, RDPLevel and USERConfig fields.

WRPState is only useful when you set OBInit.WRPState to OB_WRPSTATE_EBABLE or OB_WRPSTATE_DISABLE and then feed OBInit to the HAL_FLASHEx_OBProgram().