I am trying to write code to set the BOR Level under program control but cannot get the result I need.

[arthurg]

Posted on December 14, 2016 at 23:50

I am trying to write code to set the BOR Level under program control but cannot get the result I need. I have the following:

if ((FLASH_GetUserOptionByte() & 0x0F) != OB_BOR_LEVEL4)

{

      FLASH_UnlockOptionByte();

     FLASH_ClearFlag(FLASH_FLAG_EOP | FLASH_FLAG_WRPERR |

           FLASH_FLAG_PGAERR | FLASH_FLAG_SIZERR | FLASH_FLAG_OPTVERR);

     FLASH_SetBORResetLevel(OB_BOR_LEVEL4);

     FLASH_LockOptionByte();

     FLASH_OBLLaunch();

} 

If I have a current BOR level 3, it remains at level 3. The attempt to write level 4 fails. I am using IAR and single step. I see the bits reset in the PECR register, and the attempt to write OBR register with level 4, but it does not update with the correct value.

What am I doing wrong in the code? 

[arthurg]

Posted on December 14, 2016 at 23:52

I forgot to specify: STM32L151

[Oliver Beirne]

Posted on December 15, 2016 at 00:53

Hi Art

I have moved this thread to the

https://community.st.com/community/stm32-community/stm32-forum?sr=search&searchId=6684b0be-48c4-424e-83fd-1c831eb04a0f&searchIndex=0

‌ where a product related questions are held.

Thanks

Oli

[Tesla DeLorean]

Posted on December 15, 2016 at 03:27

Would you need to unlock the flash controller, and erase the option bytes?

[arthurg]

Posted on December 15, 2016 at 04:48

Thanks for trying to help me.

The User Manual - RM0038 (STM32L151)  - doesn't show a specific  mechanism for unlocking the controller as a whole. Instead there are separate bits for locking/unlocking the program, data, and option bytes. If you know of an additional place/register where this takes please I would appreciate knowing about it.

As for erasing, wouldn't the act of writing a new value altogether suffice?

[Walid FTITI_O]

Posted on December 15, 2016 at 10:35

Hi

,

try to apply similar code as the one implemented in the 'BOR' example inside the STM32L1xx standard peripheral library as follow:

/* Get BOR Option Bytes */ BOROptionBytes = FLASH_OB_GetBOR(); if((BOROptionBytes & 0x0F) != BOR_LEVEL) { /* Unlocks the option bytes block access */ FLASH_OB_Unlock();/* Clears the FLASH pending flags */ FLASH_ClearFlag(FLASH_FLAG_EOP|FLASH_FLAG_WRPERR | FLASH_FLAG_PGAERR | FLASH_FLAG_SIZERR | FLASH_FLAG_OPTVERR);/* Select the desired V(BOR) Level ---------------------------------------*/ FLASH_OB_BORConfig(BOR_LEVEL);/* Launch the option byte loading */ FLASH_OB_Launch(); }�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

Hope this clarify and respond to you question. If the response is correct, you press correct button.

-Walid F-

[Tuttle.Darrell]

Posted on December 15, 2016 at 12:21

I think you need to lock after launch. Flash_OB_Launch() launches the programming process so it would make sense to lock afterwards.

Using the standard peripheral library, here is what I do to make sure my BOR is set to what I want:

if(FLASH_OB_GetBOR() !=

OB_BOR_LEVEL3

) {  FLASH_OB_Unlock();  FLASH_OB_BORConfig(

OB_BOR_LEVEL3

);  FLASH_OB_Launch();  FLASH_OB_Lock(); }

Note: it is unnecessary to mask out any bits after the call to 

FLASH_OB_GetBOR() as the necessary masking is performed within that function (at least in my version of the standard peripherals lib: STM32F4xx_DSP_StdPeriph_Lib_V1.7.1  source code file: stm32f4xx_flash.c)

Instructions from stm32f4xx_flash.c (standard peripheral library):

Any operation of erase or program should follow these steps:

(#) Call the FLASH_OB_Unlock() function to enable the FLASH option control register access

(#) Call one or several functions to program the desired Option Bytes:

(++) void FLASH_OB_WRPConfig(uint32_t OB_WRP, FunctionalState NewState) => to Enable/Disable the desired sector write protection (++) void FLASH_OB_RDPConfig(uint8_t OB_RDP) => to set the desired read Protection Level (++) void FLASH_OB_UserConfig(uint8_t OB_IWDG, uint8_t OB_STOP, uint8_t OB_STDBY) => to configure the user Option Bytes. (++) void FLASH_OB_BORConfig(uint8_t OB_BOR) => to set the BOR Level

(#) Once all needed Option Bytes to be programmed are correctly written,

call the FLASH_OB_Launch() function to launch the Option Bytes programming process. -@- When changing the IWDG mode from HW to SW or from SW to HW, a system reset is needed to make the change effective.

(#) Call the FLASH_OB_Lock() function to disable the FLASH option control

register access (recommended to protect the Option Bytes against possible unwanted operations)