Setting Option Bytes with cube programmer CLI

[tstokes]

I'm trying to develop a script to flash a secure firmware and set the option bytes on STM32H755. (more on that here https://community.st.com/t5/stm32-mcus-security/flashing-sbsfu-combined-binary-to-stm32h755-with-stm32/m-p/836377#M8786)

 

My specific question here is about the -ob option in the cube programmer CLI. 

 

I'm keen to understand the difference between doing 

set cube_programmer_cli="C:\Program Files\STMicroelectronics\STM32Cube\STM32CubeProgrammer\bin\STM32_Programmer_CLI.exe"

%cube_programmer_cli% -c port=SWD mode=UR ^
 -w %fw_bin% %fw_base% ^
 -ob nWRP0=0 ^
 -ob SWAP_BANK=0x0 ^

and

set cube_programmer_cli="C:\Program Files\STMicroelectronics\STM32Cube\STM32CubeProgrammer\bin\STM32_Programmer_CLI.exe"

%cube_programmer_cli% -c port=SWD mode=UR ^
 -w %fw_bin% %fw_base% ^
 -ob nWRP0=0 SWAP_BANK=0x0
​

 

Do the two examples produce different operations and if so how? 

 

 

 

 

Both syntaxes work, but there’s a small difference:

• Writing -ob multiple times runs separate option-byte write operations, one after another.

• Writing them all in a single -ob applies the changes together in one operation.

In most cases the end result is the same, but grouping them in one -ob is cleaner and avoids any chance of temporary invalid states between writes.