Programming Option Bytes STM32L4xx using Hal API

Question

I am trying to implement a bank swap mechanism for STM32L471RET6. my Code Doesn't seem to have errors for setting and resetting Option bytes but Nothing Happens when Calling the bank Swap Functions. after I checked the option bytes using STM32CubeProgrammer, I realized that the option bytes didn't changed. Here is my bank swap function.

HAL_StatusTypeDef SwapBank(void)
{
 FLASH_OBProgramInitTypeDef OB;
 HAL_FLASHEx_OBGetConfig(&OB);
if (OB.USERConfig & OB_DUALBANK_DUAL)
{
 if (OB.USERConfig & OB_BFB2_ENABLE)
 {
 HAL_FLASH_Unlock();
 HAL_FLASH_OB_Unlock();
 OB.OptionType = OPTIONBYTE_USER;
 OB.USERType = OB_USER_BFB2;
 OB.USERConfig = OB_BFB2_DISABLE;
 }
 else
 {
 OB.OptionType = OPTIONBYTE_USER;
 OB.USERType = OB_USER_BFB2;
 OB.USERConfig = OB_BFB2_ENABLE;
 }
 if (HAL_FLASHEx_OBProgram(&OB) != HAL_OK)
 {
 HAL_FLASH_OB_Lock();
 HAL_FLASH_Lock();
 return HAL_ERROR;
 }
 HAL_FLASH_OB_Launch();
 HAL_FLASH_OB_Lock();
 HAL_FLASH_Lock(); 
 NVIC_SystemReset();
 return HAL_OK;
 }
 return HAL_ERROR;
}

I checked The STM32L4xx reference manual for programming Option bytes. I searched for it and asked for help from AI tools But I failed. I had written this program and mechanism for STM32L0 successfully and it is working but I don't Know what's wrong with STM32L471RET6.

Answer 1

Fixed...

HAL_StatusTypeDef SwapBank(void)
{
 FLASH_OBProgramInitTypeDef OB;
 HAL_FLASHEx_OBGetConfig(&OB);
if (OB.USERConfig & OB_DUALBANK_DUAL)
{
 HAL_FLASH_Unlock();
 HAL_FLASH_OB_Unlock();
 if (OB.USERConfig & OB_BFB2_ENABLE)
 {
 OB.OptionType = OPTIONBYTE_USER;
 OB.USERType = OB_USER_BFB2;
 OB.USERConfig = OB_BFB2_DISABLE;
 }
 else
 {
 OB.OptionType = OPTIONBYTE_USER;
 OB.USERType = OB_USER_BFB2;
 OB.USERConfig = OB_BFB2_ENABLE;
 }
 if (HAL_FLASHEx_OBProgram(&OB) != HAL_OK)
 {
 HAL_FLASH_OB_Lock();
 HAL_FLASH_Lock();
 return HAL_ERROR;
 }
 
 HAL_FLASH_OB_Launch();
 HAL_FLASH_OB_Lock();
 HAL_FLASH_Lock(); 
 NVIC_SystemReset();
 return HAL_OK;
 }
 return HAL_ERROR;
}