PCF2129A datasheet(27/69 Pages) NXP

27 / 69 page

PCF2129A_2

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Product data sheet

Rev. 02 — 7 May 2010

27 of 69

NXP Semiconductors

PCF2129A

Integrated RTC, TCXO and quartz crystal

8.9 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 15).

The generation of interrupts from the alarm function is described in Section 8.12.4.

8.9.1 Register Second_alarm

[1]

Default value.

(1) Only when all enabled alarm settings are matching.

Fig 15. 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

example

AE_M

MINUTE TIME

SECOND TIME

SECOND ALARM

AE_S

Table 25.

Second_alarm - second alarm register (address 0Ah) bit description

Bit

Symbol

Value

Place value Description

AE_S

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

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