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Field
Name
R/W
Description
31:16
Reserved
RTC calibration register (RTC_CAL)
This register is in write protection state.
Offset address: 0x3C
Power-on reset value: 0x0000 0000
System reset: 0xXXXX XXXX
Field
Name
R/W
Description
8:0
RECALF
R/W
Reduced Calibration Frequency
Reduced calendar frequency: Shield RECALF pulses within 2
20
RTCCLK
pulses (32sec if the output frequency is 32768 Hz) and the calendar frequency
will be reduced (the resolution is 0.9537 ppm).
Increased calendar frequency: It takes effect at the same time with ICALFEN
12:9
Reserved
13
CAL16CFG R/W
16 Second Calibration Cycle Period Configure
When CAL16CFG is set to 1, 16-second calibration cycle is used, and it
cannot be set to 1 at the same time with CAL8CFG bit.
When CAL16CFG=1, RECALF[0] is always 0.
14
CAL8CFG
R/W
8 Second Calibration Cycle Period Configure
When CAL8CFG is set to 1, 8-second calibration cycle is used, and it cannot
be set to 1 at the same time with CAL16CFG bit.
When CAL8CFG=1, RECALF[1:0] is always 00.
15
ICALFEN
R/W
Increase Calibration Frequency Enable
0: RTCCLK pulse is not increased
1: One RTCCLK pulse is increased (the frequency increases by 488.5 ppm)
every 211 pulses
It takes effect at the same time with RECALF, and when the resolution is high,
the calender frequency will be reduced. If the input frequency is 32768Hz, the
number of RTCCLK pulses added in the 32-second window is determined by
the following formula:
(512*ICALFEN)–RECALF
。
31:16
Reserved
RTC tamper and multiplexing configuration register
(RTC_TACFG)
Offset address: 0x40
Power-on reset value: 0x0000 0000
System reset: 0xXXXX XXXX
Field
Name
R/W
Description
0
TP1EN
R/W
RTC_TAMP1 Input Detection Enable
0: Disable
1: Enable
1
TP1ALCFG
R/W
RTC_TAMP1 Input Active Level Configure
When TPFCSEL!=00, this bit determines that RTC_TAMP1 will trigger a
tamper detection event when the input maintains high/low level.
0: Low level
1: High level
When TPFCSEL=00, this bit determines that RTC_TAMP1 triggers a tamper
detection event when the input is on rising/falling edge.