/* RTC set Prescaler value. 
The clock needs to be stopped for this to have any effect. */
void rtc_set_prescaler(uint32_t rtc, uint16_t presc)
/* RTC set Prescaler value. 
The clock needs to be stopped for this to have any effect. */
void rtc_set_prescaler(uint32_t rtc, uint16_t presc)
{
    RTC_PRESCALER(rtc) = presc & 0xfff;
}