ST STM32F412 User Manual

RM0402 Rev 6 649/1163
RM0402 Real-time clock (RTC)
655
Note: This register is write protected. The write access procedure is described in RTC register
write protection.
22.6.17 RTC tamper and alternate function configuration register
(RTC_TAFCR)
Address offset: 0x40
Backup domain reset value: 0x0000 0000
System reset: not affected
Bits 31:16 Reserved, must be kept at reset value
Bit 15 CALP: Increase frequency of RTC by 488.5 ppm
0: No RTCCLK pulses are added.
1: One RTCCLK pulse is effectively inserted every 2
11
pulses (frequency increased by
488.5 ppm).
This feature is intended to be used in conjunction with CALM, which lowers the frequency of
the calendar with a fine resolution. if the input frequency is 32768 Hz, the number of
RTCCLK pulses added during a 32-second window is calculated as follows: (512 * CALP) -
CALM.
Refer to Section 22.3.11: RTC smooth digital calibration.
Bit 14 CALW8: Use an 8-second calibration cycle period
When CALW8 is set to ‘1’, the 8-second calibration cycle period is selected.
CALM[1:0] are stuck at “00” when CALW8=’1’.
Refer to Section 22.3.11: RTC smooth digital calibration.
Bit 13 CALW16: Use a 16-second calibration cycle period
When CALW16 is set to ‘1’, the 16-second calibration cycle period is selected. This bit must
not be set to ‘1’ if CALW8=1.
Note: CALM[0] is stuck at ‘0’ when CALW16=’1’.
Refer to Section 22.3.11: RTC smooth digital calibration.
Bits 12:9 Reserved, must be kept at reset value
Bits 8:0 CALM[8:0]: Calibration minus
The frequency of the calendar is reduced by masking CALM out of 2
20
RTCCLK pulses (32
seconds if the input frequency is 32768 Hz). This decreases the frequency of the calendar
with a resolution of 0.9537 ppm.
To increase the frequency of the calendar, this feature should be used in conjunction with
CALP.
See Section 22.3.11: RTC smooth digital calibration on page 627.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. Res.
ALARMOUT
TYPE
TSIN
SEL
TAMP1I
NSEL
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15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
TAMP
PUDIS
TAMP
PRCH[1:0]
TAMP
FLT[1:0]
TAMP
FREQ[2:0]
TAMPTS Res. Res. Res. Res. TAMPIE TAMP1TRG TAMP1E
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ST STM32F412 Specifications

General

Brand	ST
Model	STM32F412
Category	Microcontrollers
Language	English