Setting BORF on STM32G041F8 bricks the processor???

[Andrei Chichak]

STM32CubeProg 2.19.0.  STM32G041F8. MacOS 15.5. ST-Link.

I'm working on setting the brown-out rising, falling, and enable options on an STM32G041F8.

I started out by just using CubeProg to set the BOR_EN enable bit in the option bytes. Works correctly. It gives me the reaction I expected and I'm able to reconnect via CubeProg.

Next I wanted to set the BORF_LEV to something other than 3 so I can test my code. I set it to 1, hit Apply, Cube prog complains that the connection is lost and it has disconnected from the device, and now when I try and connect I just get:

17:13:46 : UR connection mode is defined with the HWrst reset mode
17:13:46 : ST-LINK SN  : 31FF6A064D4E353828580643
17:13:46 : ST-LINK FW  : V2J46S7
17:13:46 : Board       : --
17:13:46 : Voltage     : 3.31V
17:13:46 : Error: Unable to get core ID
17:13:46 : Error: No STM32 target found! If your product embeds Debug Authentication, please perform a discovery using Debug Authentication

No, I did not mess with the RDP values, just BORF_LEV.

CubeProg can't unbrick it. CubeIDE gets similar results. Unfortunately, for me, I duplicated the result in another processor so I thought I'd stop and reach out.

Any ideas as to how to unlock these things?

Thanks,

Andrei (your neighbour from The Great White North) 

[Andrei Chichak]

Okay, I officially hate this.

I figured that, since this topic got moved to the CubeProg list instead of the MCU products list, someone within ST had a thought that CubeProg is the problem. So I went ahead with my program. I wrote:

#define BORR_LEVEL OB_BOR_LEVEL_RISING_1
#define BORF_LEVEL OB_BOR_LEVEL_FALLING_1

void MachineInit(void) {
	/* OB Program structure */
	FLASH_OBProgramInitTypeDef FLASH_OBInitStruct;
	bool needsLock = false;

	/*
	 * Arrange for the highest brown out detect possible.
	 */

	HAL_FLASHEx_OBGetConfig(&FLASH_OBInitStruct);

	if (((FLASH_OBInitStruct.USERConfig & FLASH_OPTR_BOR_EN_Msk) != FLASH_OPTR_BOR_EN) ||		// BOR must be enabled
			((FLASH_OBInitStruct.USERConfig & FLASH_OPTR_BORR_LEV_Msk) != BORR_LEVEL)  ||		// Rising BOR must match needs
			((FLASH_OBInitStruct.USERConfig & FLASH_OPTR_BORF_LEV_Msk) != BORF_LEVEL))			// Falling BOR must match needs
	{
		(void) HAL_FLASH_Unlock();
		(void) HAL_FLASH_OB_Unlock();

		FLASH_OBInitStruct.OptionType = OPTIONBYTE_USER;
		FLASH_OBInitStruct.USERType = OB_USER_BOR_LEV;
		FLASH_OBInitStruct.USERConfig = BORR_LEVEL | BORF_LEVEL;
		HAL_FLASHEx_OBProgram(&FLASH_OBInitStruct);

		FLASH_OBInitStruct.OptionType = OPTIONBYTE_USER;
		FLASH_OBInitStruct.USERType = OB_USER_BOR_EN;
		FLASH_OBInitStruct.USERConfig = OB_BOR_ENABLE;
		HAL_FLASHEx_OBProgram(&FLASH_OBInitStruct);

		(void) HAL_FLASH_OB_Launch();

		needsLock = true;

	}

	if (needsLock) {
		/* Locks the option bytes block access */
		HAL_FLASH_OB_Lock();
		HAL_FLASH_Lock();
	}
}

and it worked. CubeProg now shows that the enable bit is set and the BOR levels are set to 1.

So I change my code to the way that I need it:

#define BORR_LEVEL OB_BOR_LEVEL_RISING_3
#define BORF_LEVEL OB_BOR_LEVEL_FALLING_3

no other changes. Run the program and the net result in CubeIDE is:

CubeProg won't talk to it either.

Another bricked processor.

[Maryem]

Hello @Andrei Chichak,

Apologies for the delayed response. 

Could you please attempt to connect the target under reset using STM32CubeProgrammer?

Maryem.