pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 32

• Manufacturer Part Number: pcf2127a
• Description: Integrated Rtc, Tcxo And Quartz Crystal
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF2127A_1
Product data sheet
8.10 Alarm function
As an example, if the time (seconds through to hours) is set in one access and then in a
second access the date is set, it is possible that the time may increment between the two
accesses. A similar problem exists when reading. A roll over may occur between reads
thus giving the minutes from one moment and the hours from the next. Therefore it is
advised to read all time and date registers in one access.
When one or more of the alarm bit fields are loaded with a valid second, minute, hour, day,
or weekday and its corresponding alarm enable bit (AE_x) is logic 0, then that information
is compared with the actual second, minute, hour, day, and weekday (see
The generation of interrupts from the alarm function is described in
Fig 19. Alarm function block diagram
(1) Only when all enabled alarm settings are matching.
check now signal
WEEKDAY ALARM
SECOND ALARM
WEEKDAY TIME
SECOND TIME
HOUR ALARM
MINUTE ALARM
MINUTE TIME
DAY ALARM
HOUR TIME
DAY TIME
Rev. 01 — 21 January 2010
=
=
=
=
=
AE_W
AE_S
AE_M
AE_H
AE_D
Integrated RTC, TCXO and quartz crystal
set alarm flag AF
AE_S = 1
example
013aaa236
PCF2127A
Section
1
0
(1)
© NXP B.V. 2010. All rights reserved.
Figure
8.13.4.
19).
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