R01UH0823EJ0100 Rev.1.00 Page 801 of 1823
Jul 31, 2019
RX23W Group 28. Realtime Clock (RTCe)
28.4 Interrupt Sources
There are three interrupt sources in the realtime clock. Table 28.3 lists interrupt sources for the RTC.
(1) Alarm interrupt (ALM)
This interrupt is generated according to the result of comparison between the alarm registers and realtime clock counters
(for details, refer to
section 28.3.6, Alarm Function).
Since there is a possibility that the interrupt flag may be set to 1 when the settings of the alarm registers match the clock
counters, wait for the alarm time settings to be confirmed and set the IR flag corresponding to the ALM interrupt to 0
again after modifying values of the alarm registers. Once the interrupt flag for the alarm interrupt has been set to 1 and
the state has returned to non-matching of the alarm registers and clock counters, the flag will not be set again until there
is a further match or the values of the alarm registers are modified again.
Figure 28.11 Timing Chart for the Alarm Interrupt (ALM)
(2) Periodic interrupt (PRD)
This interrupt is generated at intervals of 2 seconds, 1 second, 1/2 second, 1/4 second, 1/8 second, 1/16 second, 1/32
second, 1/64 second, 1/128 second, or 1/256 second. The interrupt interval can be selected through the RCR1.PES[3:0]
bits.
Table 28.3 RTC Interrupt Sources
Name Interrupt Sources
ALM Alarm interrupt
PRD Periodic interrupt
CUP Carry interrupt
Match while settings are being made
Clock counters
Alarm registers
Interrupt flag
(the IR flag
corresponding to
the ALM interrupt
*1
)
Wait until the alarm
time setting is
confirmed
Alarm-register settings
in progress
Flag clearing by
software
Sequence for setting the alarm
Alarm interrupt
accepted
Note 1. Refer to the Interrupt Controller section for details on the corresponding interrupt vector number.
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