Rtc Control Register (Rtc_Cr) - STMicroelectronics STM32F05 series Reference Manual

Real-time clock (RTC)
24.6.3

RTC control register (RTC_CR)

Address offset: 0x08
Power-on reset value: 0x0000 0000
System reset: not affected
31 30 29
Res. Res. Res. Res.
15 14 13
TSIE Res. Res. ALRAIE
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Bits 31:24 Reserved, must be kept at reset value.
Bit 23 COE: Calibration output enable
Bits 22:21 OSEL[1:0]: Output selection
Bit 20 POL: Output polarity
Bit 19 COSEL: Calibration output selection
Bit 18 BKP: Backup
Bit 17 SUB1H: Subtract 1 hour (winter time change)
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28 27 26 25
Res. Res. Res.
12 11 10 9
TSE Res. Res.
rw rw
This bit enables the RTC_CALIB output
0: Calibration output disabled
1: Calibration output enabled
These bits are used to select the flag to be routed to RTC_ALARM output
00: Output disabled
01: Alarm A output enabled
10: Reserved
11: Reserved
This bit is used to configure the polarity of RTC_ALARM output
0: The pin is high when ALRAF is asserted (depending on OSEL[1:0])
1: The pin is low when ALRAF is asserted (depending on OSEL[1:0]).
When COE=1, this bit selects which signal is output on RTC_CALIB.
0: Calibration output is 512 Hz
1: Calibration output is 1 Hz
These frequencies are valid for RTCCLK at 32.768 kHz and prescalers at their default values
(PREDIV_A=127 and PREDIV_S=255). Refer to
This bit can be written by the user to memorize whether the daylight saving time change has
been performed or not.
When this bit is set outside initialization mode, 1 hour is subtracted to the calendar time if the
current hour is not 0. This bit is always read as 0.
Setting this bit has no effect when current hour is 0.
0: No effect
1: Subtracts 1 hour to the current time. This can be used for winter time change.
Doc ID 018940 Rev 1
24 23 22 21
Res. COE OSEL[1:0]
rw rw rw
8 7 6 5
BYPS
ALRAE Res. FMT
HAD
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Section 24.3.14: Calibration clock output
20 19 18
POL COSEL BKP
rw rw rw
4 3 2
REFCKON TSEDGE
rw rw
RM0091
17 16
SUB1H ADD1H
w w
1 0
Res.