RX8804CE
Page - 30
ETM59E-05
When a time update interrupt event occurs (UF bit value changes from
“0”
to
”1”), this bit selects whether to
generate an interrupt signal (/INT status changes from Hi-Z to low) or to not generate it (/INT status remains
Hi-Z).
Table 55 UIE bit
UIE
Data
Description
Write / Read
0
1) Does not generate an interrupt signal when a time update interrupt event
occurs (/INT remains Hi-Z)
2) Cancels interrupt signal triggered by time update interrupt event (/INT
changes from low to Hi-Z)
Even when the UIE bit value is “0” another interrupt event may change
the /INT status to low (or may hold /INT =
L)
1
When a time update interrupt event occurs, an interrupt signal is generated
(/INT status changes from Hi-Z to low).
When a time update interrupt event occurs, low-level output from the /INT
pin occurs only when the UIE bit value is “1”. Earliest 7.813
ms after the
interrupt occurs, the /INT status is automatically cleared (/INT status
changes from low to Hi-Z)
8.7.3. Time Update Interrupt Function Timing Chart
UIE bit
/INT output
UF bit
Events
tRTN
tRTN
tRTN
period
period
period
tRTN
period
"
1
"
"
0
"
Hi-Z
"
L
"
"
1
"
"
0
"
/INT status does not
change when UF bit is
cleared to zero.
Operation in RTC
int' operation
Write operation
(1)
(2)
(3)
(4)
"
1
"
(5)
(6)
(7)
Figure 19 Update Interrupt Timing Chart
(1) A
time update interrupt event occurs when the internal clock's value matches either the second update time or
the minute update time. The USEL bit's specification determines whether it is the second update time or the
minute update time that must be matched.
(2)
When a time update interrupt event occurs, the UF bit value becomes “1”.
(3)
When the UF bit value is “1” its value is retained until it is cleared to zero.
(4) When a time update interrupt occurs, /INT pin output is low if UIE =
”1”.
If UIE =
”0” when a timer update interrupt occurs, the /INT pin status remains Hi-Z.
(5)
Each time an event occurs, /INT pin output is low only up to the tRTN time (which is fixed as 7.813 ms for
time update interrupts) after which it is automatically cleared to Hi-Z.
/INT pin output goes low again when the next interrupt event occurs.
(6)
As long as /INT
=
low, the /INT pin status does not change, even if the UF bit value changes from “1”
to “0”.
(7)
When /INT
=
low, the /INT pin status changes from low to Hi-
Z as soon as the UIE bit value changes from “1”
to
”0”.