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ETM12E-01
13.3. 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.
∗ When an alarm interrupt event occurs, low-level output from /AIRQ is not automatically reset (it can be reset only
intentionally) and the low-level status of /AIRQ is retained.
∗Example of /INT
operation
AIE = " 1 "
( AF = " 0 " → " 1 " )
AF = " 1 " → " 0 " or
AIE
=
"
1
"
→
"
0
"
13.3.1. Diagram of alarm interrupt function
IE bit
/INT output
F bit
Event
occurs
" 1 "
" 0 "
Hi - z
" L "
" 1 "
" 0 "
RTC internal operation
Write operation
(1)
(2)
(3)
(4)
"
1
"
(5)
(7)
(6)
(1) The minute, hour, day of week (weekday), and date at which an alarm interrupt event will occur is set in
advance, and the interrupt event occurs when the current time matches this pre-set time.
(2) When a time alarm 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) If the AIE bit value is "0" when an alarm interrupt occurs, the /INT pin status remains Hi-z.
