STM32H7 Series MCU VBat Connection with BackUp Domain Handlling by software?

[SEfte.1]

Hello,

I am working on a project with STM32H753 MCU and I want to reset the back up registers of the MCU every time I reset the MCU. With VBat presented on my board via external battery. The only way to do this is by writing to the specific register referred in the Datasheet or is there a Pin that can be handled by software and disconnects the back up domain from the VBat voltage? For more explanation I add the bellow photo. My Question is if I can handle the switch marked with red color in the picture by a Pin?

[waclawek.jan]

> I want to reset the back up registers of the MCU every time I reset the MCU

This is an unreasonable request. The purpose of backup registers is, that their content persists even during VDD being unavailabe, i.e. through a power reset.

Also, removing power is not the proper way to reset the backup registers. You can simply write to them zeros. Also, they are cleared by tamper, read the RTC chapter in RM.

 

> The only way to do this [disconnecting VBAT from backup domain] is by writing to the specific register referred in the Datasheet

Yes.

> or is there a Pin that can be handled by software and disconnects the back up domain from the VBat voltage?

No.

JW

[SEfte.1]

Hello and thank you for your reply,

I thought about to reset the back up domain because when I start my code it is stack in the bellow function.

 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

 {

  Error_Handler();

 }

Some Details about my project:

1 I have RTC enable and clocked by external oscilator (LSE).

2 In MCU VBat Pin I have 2 supercapacitors connected.

3 Main MCU Clock is 480MHz Powred by HSI (64MHz) with PLL.

When I start my code with supercapacitors not connected (this is done by hardware) the project is not stack in the below function and run as expected.But when I start my project with supercapacitors connected the project stack in the above function during system clock configuration. So I thought that reset the back registers will fix the problem. Any other ideas?