ST STM32F31xx User Manual

UM1581
Real-time clock (RTC)
DocID023800 Rev 1
361/584
19.2.5 RTC and low power modes
The MCU can be woken up from a low power mode by an RTC alternate function.
The RTC alternate functions are the RTC alarms (Alarm A and Alarm B), RTC wakeup,
RTC tamper event detection and RTC time stamp event detection. These RTC alternate
functions can wake up the system from the Stop and Standby lowpower modes. The
system can also wake up from low power modes without depending on an external
interrupt (Auto-wakeup mode), by using the RTC alarm or the RTC wakeup events.
The RTC provides a programmable time base for waking up from the Stop or Standby
mode at regular intervals. Wakeup from STOP and Standby modes is possible only when
the RTC clock source is LSE or LSI.
19.2.6 Selection of RTC_AF alternate functions
The RTC_AF pin (PC13) can be used for the following purposes:
 Wakeup pin 2 (WKUP2) using the PWR_WakeUpPinCmd() function.
 AFO_ALARM output
 AFO_CALIB output
 AFI_TAMPER
 AFI_TIMESTAMP
Table 15: Selection of RTC_AF alternate functions
Pin
configuration
and
functions
RTC_ALARM
output
enabled
RTC_CALIB
output
enabled
RTC_TAMPER
input enabled
RTC_TIMESTAMP
input enabled
PC13MODE
bit
PC13VALUE
bit
Alarm out
output OD
1
Don't care
Don't care
Don't care
Don't care
0
Alarm out
output PP
1
Don't care
Don't care
Don't care
Don't care
1
Calibration
out output PP
0
1
Don't care
Don't care
Don't care
Don't care
TAMPER
input floating
0
0
1
0
Don't care
Don't care
TIMESTAMP
and TAMPER
input floating
0
0
1
1
Don't care
Don't care
TIMESTAMP
input floating
0
0
0
1
Don't care
Don't care
Output PP
forced
0
0
0
0
1
PC13 output
Wakeup pin
or Standard
GPIO
0
0
0
0
0
Don't care

ST STM32F31xx Specifications

General

Brand	ST
Model	STM32F31xx
Category	Microcontrollers
Language	English