Real-time clock (RTC) RM0440
1544/2126 RM0440 Rev 4
In addition, it is possible to output RTC_OUT2 on PB2 pin thanks to OUT2EN bit. This
output is not available in V
BAT
mode. The different functions are mapped on RTC_OUT1 or
on RTC_OUT2 depending on OSEL, COE and OUT2EN configuration, as show in table
Table 332.
For PB2, the GPIO should be configured as an alternate function.
35.3.4 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 Section 7: Reset and clock control (RCC).
Wakeup pin or Standard
GPIO
00 0 0
Don’t
care
Don’t
care
Don’t
care
0000 0 1
1
Don’t
care
Don’t
care
0
1. OD: open drain; PP: push-pull.
2. In this configuration the GPIO must be configured in input.
Table 332. RTC_OUT mapping
OSEL[1:0] bits
ALARM
output enable)
COE bit (CALIB
output enable)
OUT2EN
bit
RTC_OUT1 on
PC13
RTC_OUT2 on
PB2
00 0
0
--
00 1 CALIB -
01 or 10 or 11 Don’t care TAMPALRM -
00 0
1
--
00 1 - CALIB
01 or 10 or 11 0 - TAMPALRM
01 or 10 or 11 1 TAMPALRM CALIB
Table 331. PC13 configuration
(1)
(continued)
PC13 Pin function
OSEL[1:0]
(ALARM output enable)
TAMPOE
(TAMPER output enable)
COE
(CALIB output enable)
OUT2EN
TAMPALRM_TYPE
TAMPALRM_PU
TAMP1E
(TAMP_IN1 input enable)
TSE
(RTC_TS input enable)
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