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Micro Crystal
Ultra Small Real-Time Clock Module with I
2
C-Bus Interface
RV-8263-C7
January 2019
26/61
Rev. 1.0
ALARM FUNCTION
4.6.
By clearing the alarm enable bit (AE_x) of one or more of the alarm registers, the corresponding alarm condition(s)
are active. When an alarm occurs, AF is set logic 1. The asserted AF can be used to generate an interrupt (
INT
̅̅̅̅̅
).
The AF is cleared by command.
The registers at addresses 0Bh through 0Fh contain alarm information. When one or more of these registers is
loaded with second, minute, hour, date or weekday, and its corresponding AE_x is logic 0, then that information is
compared with the current second, minute, hour, date, and weekday. When all enabled comparisons first match,
the Alarm Flag (AF in CONTROL REGISTERS, 01h
– Control2) is set logic 1.
Alarm function block diagram:
SECOND ALARM
SECOND TIME
=
MINUTE ALARM
MINUTE TIME
=
HOUR ALARM
HOUR TIME
=
DATE ALARM
DATE TIME
=
WEEKDAY ALARM
WEEKDAY TIME
=
check now signal
ALARM
CONTROL
1
0
AE_S
1
0
AE_M
1
0
AE_H
1
0
AE_D
1
0
AE_W
ALARM FLAG
AF
SET
CLEAR
(1)
from interface:
clear AF
to interface:
read AF
INT
0
1
AIE
(1)
Only when all enabled alarm settings are matching.
It is only on increment to a matched case that the Alarm Flag is set.
ALARM INTERRUPT
4.6.1.
The generation of interrupts from the alarm function is controlled via bit AIE. If bit AIE is enabled, the
INT
̅̅̅̅̅
pin
follows the condition of bit AF. AF remains set until cleared by command. Once AF has been cleared, it will only be
set again when the time increments to match the alarm condition once more. Alarm registers which have their AE_x
bit at logic 1 are ignored.