/* Writes user data to the specified data Backup Register immediately.  */
void exBKP_ImmWrite(BKPDR_Typedef bkp_dr, u16 dat)
/* Writes user data to the specified data Backup Register immediately.  */
void exBKP_ImmWrite(BKPDR_Typedef bkp_dr, u16 dat)
{
    RCC->BDCR |= RCC_BDCR_DBP;
    *(vu16*)(BKP_BASE + bkp_dr) = dat;
    RCC->BDCR &= ~RCC_BDCR_DBP;
}