RX − 8801 SA / JE

8.5. 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 "

( AF = " 0 " → " 1 " )

AF = " 1 " → " 0 " or

 

 

AIE = " 1 " → " 0 "

8.4.1.Diagram of alarm interrupt function

"1 "

AIE bit

(4)

" 1 "

 

 

" 0 "

 

 

 

 

(5)

/INT output

(7)

Hi - z

 

" L "

 

 

 

(6)

 

AF bit

(3)

" 1 "

(2)

" 0 "

 

 

Event

(1)

 

 

 

occurs

 

 

RTC internal operation

Write operation

(1)The hour, minute, date or day when an alarm interrupt event is to occur is set in advance along with the WADA bit, and when the setting matches the current time an interrupt event occurs.

(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 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)If the AIE bit value is "0" when an alarm interrupt occurs, the /INT pin status remains Hi-Z.

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ETM26E-03