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RA8804 CE
8.7. Alarm Interrupt Function
The alarm interrupt generation function generates interrupt events for alarm settings such as date, day, hour, and
minute settings.
When an interrupt event occurs, the AF bit value is set to "1" and the /INT pin goes to low level to indicate that an
event has occurred.
Example of
/INT operation
AIE ="1"
8.7.1. Diagram of alarm interrupt function
AIE bit
/INT output
AF bit
Event
occurs
RTC internal operation
Write operation
(1) The minute, hour, day and date, when an alarm interrupt event is supposed to occur has to be set in advance,
along with the WADA bit
occur until the counter counts up to the current date/time (i.e., an alarm will occur next time, not immediately).
(2) When a time update interrupt event occurs, the AF bit values becomes "1".
(3) When the AF bit = 1, its value is retained until it is cleared to zero.
(4) If AIE = 1 when an alarm interrupt occurs, the /INT pin output goes low.
When an alarm interrupt event occurs, /INT pin output goes low, and this status is then held until it is cleared
via the AF bit or AIE bit.
(5) If the AIE value is changed from "1" to "0" while /INT is low, the /INT status immediately changes from low to
Hi-Z. After the alarm interrupt occurs and before the AF bit value is cleared to zero, the /INT status can be
controlled via the AIE bit.
(6) If the AF bit value is changed from "1" to "0" while /INT is low, the /INT status immediately changes from low to
Hi-Z.
(7) When the AIE bit value is "0", and an alarm interrupt occurs, the /INT pin stay Hi-Z.
( AF="0""1" )
"1"
(4)
(5)
(6)
(3)
(2)
(1)
(Note) Even if the current date/time is used as the setting, the alarm will not
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AF="1""0"or
AIE="1""0"
(7)
"1"
"0"
Hi-z
"L"
"1"
"0"
ETM60E-02
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