hasenbanck

This might also work for other STM32 chips. I use the HAL, so it also might be supported by your chip.

To use the Backup SRAM (most of the time 4 Kb), you need to add a backup power source (like a battery or a supercap)
to the VBAT pin of your STM32. I use a simple CR2032 battery.

Use following code to get access to the Backup SRAM:

  __HAL_RCC_PWR_CLK_ENABLE();
  HAL_PWR_EnableBkUpAccess();
  __HAL_RCC_BKPSRAM_CLK_ENABLE();