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timestamp register.
The timestamp polarity is detected through TSETECFG bit of the register
RTC_CTRL. When RTC_TS pin recognizes the external timestamp edge signal,
RTC will automatically latch the current date in the subsecond, time and date
timestamp registers, and the timestamp flag bit TSFLG will be set to 1. If the
timestamp interrupt is enabled, the timestamp interrupt processing will be
triggered.
When TSFLG flag bit is set to 1, and a timestamp event occurs, the timestamp
will overrun, and the flag bit TSOVRFLG will be set to 1. If a timestamp event is
detected once TSFLG flag is cleared, both TSFLG and TSOVRFLG flags will be
set to 1.
TAMPER multiplexing function
RTC_TAMP1 multiplexing function can be mapped to RTC_AF1 or RTC_AF2,
and it is determined by TP1MSEL bit of RTC_TACFG register. After TP1MSEL is
modified, clear TP1EN bit to zero to avoid accidental setting of TP1FLG.
Corresponding RTC_TAMP2 pin of RTC_TAMP2 multiplexing function.
Backup domain
After the main power supply V
DD
is powered off, the backup domain register will
be powered by V
BAT
automatically. System resetting, NRST pin resetting, and
resetting after the low mode is waken up will not affect the backup domain
register. When V
BAT
is powered off or tamper event occurs, the backup domain
register will be reset.
The backup domain register can be used to cache user data, and can be used
as a state flag to realize some function application by using the characteristics
that the system reset data will remain unchanged.
Tamper detection
Tamper detection is a kind of data self-destruction protection device to prevent
data leakage caused by tamper. Through the hardware circuit design, the
tamper detection signal is sent to the tamper detection pin.
Tamper detection has multiple tamper detection pins, and each pin is enabled
by a register bit separately. In order to detect real tamper events better, signal
filtering can be configured, and tamper detection polarity can be configured for
each pin.
Tamper detection polarity
The low level/rising edge and high level/falling edge can be selected as tamper
detection polarity through TPxAL bit in the register RTC_TACFG.