Real-Time Clock
7-183
MPU Public Peripherals
Table 7–140. RTC Status Register (RTC_STATUS_REG)
Bit
Name
Value
Function
R/W
Reset
Value
7
POWER_UP
†
Indicates that a reset occurred
R/W
1
6
ALARM
‡
Indicates that an alarm interrupt has been
generated
R/W
0
5
1D_EVENT
One day has occurred
R
0
4
1H_EVENT
One hour has occurred
R
0
3
1M_EVENT
One minute has occurred
R
0
2
1S_EVENT
One second has occurred
R
0
1
RUN
§
0
RTC is frozen
R
0
1
RTC is running
0
BUSY
0
Updating event in more than 15
µ
s
R
0
1
Updating event
† POWER_UP is set by a reset and cleared by writing 1 to this bit.
‡ The alarm interrupt keeps its low level until the MPU writes 1 in the ALARM bit of this register. The timer interrupt is a low-level
pulse (15
µ
s duration).
§ The STOP_RTC signal is synchronized on the 32-kHz clock, so only 1 clock period can elapse between the write to STOP_RTC
and the RTC actually being stopped. The RUN bit shows the actual state of the RTC.
Table 7–141. RTC Interrupts Register (RTC_INTERRUPTS_REG)
Bit
Name
Value
Function
R/W
Reset
Value
7–4
Reserved
R
0000
3
IT_ALARM
Enable one interrupt when the alarm value is
reached (time and calendar alarms) by the time
and calendars.
R/W
0
2
IT_TIMER
Enable periodic interrupt
R/W
0
0
Interrupt disabled
1
Interrupt enabled
Note:
The MPU must respect the busy period to prevent spurious interrupt.