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Page - 20 MQ372-02
3) AF (Alarm Flag) bit
When this flag bit value is already set to "0", occurrence of an alarm interrupt event changes it to "1". When this
flag bit value is "1", its value is retained until a "0" is written to it.
AF
Data Description
0
The AF bit is cleared to zero to prepare for the next status detection
∗
Clearing this bit to zero enables /INT low output to be canceled (/INT remains Hi-Z) when an alarm
interrupt event has occurred.
Write
1 This bit is invalid after a "1" has been written to it.
0 Alarm interrupt events are not detected.
Read
1
Alarm interrupt events are detected.
(Result is retained until this bit is cleared to zero.)
4) AIE (Alarm Interrupt Enable) bit
When an alarm interrupt event occurs (when the AF bit value changes from "0" to "1"), this bit's value specifies
whether an interrupt signal is generated (/INT status changes from Hi-Z to low) or is not generated (/INT status
remains Hi-Z).
AIE
Data Description
0
1) When an alarm interrupt event occurs, an interrupt signal is not
generated or is canceled (/INT status remains Hi-Z).
2) When an alarm interrupt event occurs, the interrupt signal is canceled
(/INT status changes from low to Hi-Z).
∗
Even when the AIE bit value is "0" another interrupt event may change the /INT status to low
(or may hold /INT = "L").
Write/Read
1
When an alarm interrupt event occurs, an interrupt signal is generated (/INT
status changes from Hi-Z to low).
∗
When an alarm interrupt event occurs, low-level output from the /INT pin occurs only when the
AIE bit value is "1". This value is retained (not automatically cleared) until the AF bit is cleared
to zero.
8.5.2. Examples of alarm settings
1) Example of alarm settings when "Day" has been specified (and WADA bit = "0")
Reg – A Reg - 9 Reg - 8
Day is specified
WADA bit = "0"
bit
7
AE
bit
6
S
bit
5
F
bit
4
T
bit
3
W
bit
2
T
bit
1
M
bit
0
S
HOUR
Alarm
MIN
Alarm
Monday through Friday, at 7:00 AM
∗ Minute value is ignored
00111110 07 h
80 h ∼ FF h
Every Saturday and Sunday, for 30 minutes
each hour ∗ Hour value is ignored
01000001
80 h ∼ FF h
30 h
01111111
Every day, at 6:59 AM
1
Χ Χ Χ Χ Χ Χ Χ
18 h 59 h
Χ: Don't care
2) Example of alarm settings when "Day" has been specified (and WADA bit = "1")
Reg - A Reg - 9 Reg - 8
Day is specified
WADA bit = "1"
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
00000001 07 h
80 h ∼ FF h
15
th
of each month, for 30 minutes each
hour ∗ Hour value is ignored
00010101
80 h ∼ FF h
30 h
Every day, at 6:59 PM 1
Χ Χ Χ Χ Χ Χ Χ
18 h 59 h
Χ: Don't care