Datasheet

PCF2127AT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6 — 11 July 2013 34 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
8.10 Alarm function
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 Figure 19
).
The generation of interrupts from the alarm function is described in Section 8.13.5.
8.10.1 Register Second_alarm
[1] Default value.
(1) Only when all enabled alarm settings are matching.
Fig 19. Alarm function block diagram
013aaa236
WEEKDAY ALARM
AE_W
WEEKDAY TIME
=
DAY ALARM
AE_D
DAY TIME
=
HOUR ALARM
AE_H
HOUR TIME
=
MINUTE ALARM
=
check now signal
set alarm flag AF
(1)
AE_S = 1
1
0
example
AE_M
MINUTE TIME
=
SECOND TIME
SECOND ALARM
AE_S
Table 30. Second_alarm - second alarm register (address 0Ah) bit description
Bit Symbol Value Place value Description
7 AE_S 0 - second alarm is enabled
1
[1]
- second alarm is disabled
6 to 4 SECOND_ALARM 0 to 5 ten’s place second alarm information coded in BCD
format
3to0 0to9 unit place