ST STM32F301 6 Series Reference Manual page 606

Real-time clock (RTC)
24.3 RTC functional description
24.3.1 RTC block diagram
RTC_TAMP2
RTC_TAMP1
RTC_TS
RTC_REFIN
LSE
HSE/32
LSI
RTCCLK
RTC_CALR
Smooth
calibration
WUCKSEL[1:0]
Prescaler
1, 2, 4, 8, 16
606/874
Figure 245. RTC block diagram
Backup registers
and RTC tamper
control registers
ck_apre
RTC_PRER
(default 256 Hz)
Asynchronous
7-bit prescaler
(default = 128)
1 Hz
512 Hz
RTC_WUTR
16-bit wakeup
auto reload timer
Alarm A
RTC_ALRMAR
RTC_ALRMASSR
Alarm B
RTC_ALRMBR
RTC_ALRMBSSR
RM0366 Rev 5
Time stamp
registers
ck_spre
RTC_PRER
(default 1 Hz)
Synchronous
15-bit prescaler
(default = 256)
Shadow registers
Shadow register
RTC_SSR
RTC_CALIB
RTC_ALARM
=
RM0366
TAMPxF
TSF
Calendar
RTC_TR,
RTC_DR
Output
RTC_OUT
control
WUTF
OSEL[1:0]
ALRAF
=
ALRBF
MSv42054V3