STM32H vbat

[Paulo Rego]

Hello everybody,

My name is Rego, as a hobby I work on displays, image processing, etc...

I'm not very familiar with ST, but I'm really enjoying these MCU.

I've already implemented RTC using VBAT and it works very well. Now I want SRAM backup,

On battery it loses data I can't understand the reason for the problem, can anyone help me?

thanks

[waclawek.jan]

Ib don't use the 'H7 family but in other Hamilton for the backup SRAM to work under VBAT supply, a dedicated internal voltage regulator has to be switched on (in PWR module) Try to search for it in Reference Manual (RM).

JW

[Paulo Rego]

Did you refer to this?

Thanks,

Rego

[Pavel A. · Accepted solution]

Last time I did this on STM32H743-EVAL board, years ago.

If memory serves: enable the backup domain power regulator with HAL_PWREx_EnableBkUpReg()

Then unlock access to the backup RAM to read and write:

// Unlock access to backup RAM
void unlock_bkp_RAM(void)
{
    __HAL_RCC_BKPRAM_CLK_ENABLE();
    __DMB();
    if (!LL_PWR_IsEnabledBkUpAccess())
    {
      HAL_PWR_EnableBkUpAccess();
      __DMB();
    }
}

If the battery is rechargeable, you may need to turn on/off the charger, by HAL_PWREx_EnableBatteryCharging and HAL_PWREx_DisableBatteryCharging.

The Cube FW_H7 software package has examples of backup RAM and RTC registers use, look at these.

Enjoy.

[Paulo Rego]

Thanks for your help, it finally works,,!!👍

Regards,

Rego