RX8804CE
Page - 23
ETM59E-05
2) Example of Alarm Settings when Day has been Specified (and WADA bit
=
”1”)
Table 43 Alarm Setting ex.2
Day is specified
WADA bit = 1
Reg - A
Reg - 9
Reg - 8
bit
7
AE
bit
6
•
bit
5
20
bit
4
10
bit
3
08
bit
2
04
bit
1
02
bit
0
01
HOUR
Alarm
MIN
Alarm
First of each month, at 7:00 AM
Minute value is ignored
0 0 0 0 0 0 0 1
0 h
AE = 1
15
th
of each month, for 30 minutes each
hour
Hour value is ignored
0 0 0 1 0 1 0 1
AE = 1
30h
Every day, at 6:59 PM
1 X X X X X X X
18h
59h
X: Don't care
8.5.4. Alarm Interrupt Timing Chart
AIE bit
/INT output
AF bit
Event
occurs
"
1
"
"
0
"
Hi-Z
"
L
"
"
1
"
"
0
"
(1)
(2)
(3)
(4)
"
1
"
(5)
(7)
(6)
RTC internal operation
Write operation
Figure 13 Alarm Timing Chart
(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 (Note) Even if the current date/time is used as the setting, the alarm will not 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 up
date 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.