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7FFA
7FFB
7FFC
7FFD
7FFE
7FFF
0000
0001
CLK
32 kHz
Timer
Counter
Second
Update
No Compensation
7FFA
7FFB
7FFC
7FFD
7FFE
7FFF
0002
0003
CLK
32 kHz
Timer
Counter
Second
Update
Negative Compensation: comp_req = +2
2 Cycles are
Removed from
Next Second
7FFA
7FFB
7FFC
7FFD
7FFE
7FFF
7FFE
7FFF
CLK
32 kHz
Timer
Counter
Second
Update
Positive Compensation: comp_req = –2 (0xFFFE)
2 Cycles are Added to
Current Second
0000
Architecture
1324
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Real-Time Clock (RTC)
Figure 27-2. 32-kHz Oscillator Counter Compensation
27.2.5 Interrupt Requests
The RTC provides the ability to interrupt the CPU based on two events: a periodic interrupt and an alarm
interrupt. Although two interrupt sources are available, the RTC makes a single interrupt request to the
CPU.
When the device is initially powered on, the RTC may issue spurious interrupt signals to the CPU. To
avoid issues, a software reset should be performed on the RTC module before the CPU interrupt
controller is initialized. See
for more information on reset considerations.
27.2.5.1 Alarm Interrupt Enable and Status Bits
The ALARM bit in the interrupt register (INTERRUPT) enables the alarm interrupt. When the current time
and date match the ALARMSECOND, ALARMMINUTE, ALARMHOUR, ALARMDAY, ALARMMONTH,
and ALARMYEAR registers, the RTC issues an interrupt to the CPU and sets the ALARM bit in the status
register (STATUS). Once set, the ALARM status bit stays high until cleared by a write of 1 to the ALARM
bit.
As with writing to time and calendar registers (
), writes to the INTERRUPT and STATUS
registers should only be done when the RTC is stopped or when the BUSY bit is low.
Note that all registers in the RTC except for KICK
n
R have write-protection. See
for
information on unlocking registers.