Rtc Functional Description - ST STM32F413 Reference Manual

RM0430
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Timestamp function for event saving (1 event)
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Tamper detection:
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20 backup registers (80 bytes). The backup registers are reset when a tamper
detection event occurs.
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Alternate function output (RTC_OUT) which selects one of the following two outputs:
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–
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RTC alternate function inputs:
–
–
–
Refer to
25.3

RTC functional description

25.3.1 Clock and prescalers
The RTC clock source (RTCCLK) is selected through the clock controller among the LSE
clock, the LSI oscillator clock, and the HSE clock. For more information on the RTC clock
source configuration, refer to .
A programmable prescaler stage generates a 1 Hz clock which is used to update the
calendar. To minimize power consumption, the prescaler is split into 2 programmable
prescalers (see
•
A 7-bit asynchronous prescaler configured through the PREDIV_A bits of the
RTC_PRER register.
•
A 15-bit synchronous prescaler configured through the PREDIV_S bits of the
RTC_PRER register.
Note: When both prescalers are used, it is recommended to configure the asynchronous prescaler
to a high value to minimize consumption.
The asynchronous prescaler division factor is set to 128, and the synchronous division
factor to 256, to obtain an internal clock frequency of 1 Hz (ck_spre) with an LSE frequency
of 32.768 kHz.
The minimum division factor is 1 and the maximum division factor is 2
This corresponds to a maximum input frequency of around 4 MHz.
0.95 ppm accuracy, obtained in a calibration window of several seconds
2 tamper events with configurable filter and internal pull-up.
RTC_CALIB: 512 Hz or 1 Hz clock output (with an LSE frequency of 32.768 kHz).
This output is enabled by setting the COE bit in the RTC_CR register. It is routed
to the device RTC_AF1 function.
RTC_ALARM (Alarm A, Alarm B or wakeup).
This output is selected by configuring the OSEL[1:0] bits in the RTC_CR register.
It is routed to the device RTC_AF1 function.
RTC_TS: timestamp event detection. It is routed to the device RTC_AF1.
RTC_TAMP1: TAMPER1 event detection. It is routed to the device RTC_AF1.
RTC_REFIN: reference clock input (usually the mains, 50 or 60 Hz).
Section 7.3.15: Selection of RTC additional
Figure 241. RTC block diagram
Figure 241: RTC block diagram):
DocID029473 Rev 3
Real-time clock (RTC)
functions.
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