STM32H745 set CM7 boot addr0 from CM4

[Sander-W]

I'm using a STM32H745 and running a bootloader on the CM4. In the bootloader I want to set the boot address of the CM7 using the user option bytes. 

Is this possible and if so, how should I do this?

Kind regards

[SofLit]

I don't see a constraint to do that.

How to modify an option byte? refer to the RM0399 / section 4.4.3 Option byte modification.

An example how to modify option byte is provided here for Flash BANK swapping example.

[Sander-W]

I'm using the following to set the boot address for the M7 core from the M4 core application. But somehow the boot address remains the same. Any suggestions?

{
	FLASH_OBProgramInitTypeDef OB;
	HAL_FLASHEx_OBGetConfig(&OB);

	OB.OptionType = OPTIONBYTE_CM7_BOOTADD;
	OB.BootAddr0 = 0x08010000;

	HAL_FLASH_Unlock();
	HAL_FLASH_OB_Unlock();

	if ( HAL_FLASHEx_OBProgram(&OB) != HAL_OK )
	{
		return ;
	}

	HAL_FLASH_OB_Launch();
}

[SofLit · Accepted solution]

You're missing:

OBInit.BootConfig = OB_BOOT_ADD0;

This sequence is working well from CM4 side:

  HAL_FLASH_Unlock();
  HAL_FLASH_OB_Unlock();
  HAL_FLASHEx_OBGetConfig(&OBInit);
	
  OBInit.OptionType = OPTIONBYTE_CM7_BOOTADD;
  OBInit.BootAddr0 = 0x08010000;
  OBInit.BootConfig = OB_BOOT_ADD0;
  HAL_FLASHEx_OBProgram(&OBInit);
  HAL_FLASH_OB_Launch()