14. Functions
RX8130CE
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ETM50E-07
Seiko Epson Corporation
35
14.4. Time Update Interrupt Function
The time update interrupt function generates interrupt in one-second or one-minute intervals which are
synchronized to the update of the second or minute time register of the RTC When an interrupt event is
generated, This /IRQ status is automatically cleared (/IRQ status changes from low level to Hi-z earliest
7.57ms (maximum 15.63ms) after the interrupt occurs).
14.4.1. Related registers for time update interrupt functions.
Address
h
Function
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
1C
Extension Register
FSEL1 FSEL0
USEL
TE
WADA
TSEL2 TSEL1 TSEL0
1D
Flag Register
VBLF
0
UF
TF
AF
RSF
VLF
VBFF
1E
Control Register0
TEST
STOP
UIE
TIE
AIE
TSTP TBKON TBKE
Before entering settings for operations, we recommend writing a "0" to the UIE bit to prevent hardware
interrupts from occurring inadvertently while entering settings.
When the STOP bit value is "1"
time update interrupt events do not occur.
Although the time update interrupt function cannot be fully stopped, if "0" is written to the UIE bit, the time
update interrupt function can be prevented from changing the /IRQ pin status to low.
1) USEL bit ( Update Interrupt Select )
This bit is used to select "second" update or "minute" update as the timing for generation of time
update interrupt events.
Table 28 Second/Minute selection
2) UF bit
(
Update Flag
)
This flag bit value changes from "0" to "1" when a time update interrupt event occurs.
Table 29 Time update Flag
UF
Data
Description
Write
0
Clearing this bit to zero enables /IRQ low output to be canceled (/IRQ remains
Hi-z) when a time update interrupt event has occurred
.
1
Invalid (writing a 1 will be ignored
Read
0
1
Time update interrupt events are detected.
(The result is retained until this bit is cleared to zero.)
3) UIE bit
(
Update Interrupt Enable
)
This bit selects whether to generate an interrupt signal or to not generate it.
Table 30 Time update interrupt control
UIE
Data
Description
Write / Read
0
1) Does not generate an interrupt signal when a time update interrupt event
occurs (/IRQ remains Hi-Z)
2) Cancels interrupt signal triggered by time update interrupt event (/IRQ
changes from low to Hi-Z).
Even when the UIE bit value is "0" another interrupt event may change the /IRQ status to low (or
may hold /IRQ =
"L").
1
When a time update interrupt event occurs, an interrupt signal is generated
(/IRQ status changes from Hi-Z to low).
When a time update interrupt event occurs, low-level output from the /IRQ pin occurs only when
the UIE bit value is "1". Earliest 7.57
ms after the interrupt occurs, the /IRQ status is automatically
cleared (/IRQ status changes from low to Hi-Z).
USEL
Data
Description
Write
0
Selects "second update" (once per second) as the timing for generation of
interrupt events
1
Selects "minute update" (once per minute) as the timing for generation of
interrupt events