PCF2123TS datasheet(8/55 Pages) NXP

8 / 55 page

PCF2123_2

Product data sheet

Rev. 02 — 4 December 2009

8 of 55

NXP Semiconductors

PCF2123

SPI Real time clock/calendar

9.2 Register overview

16 registers are available. The time registers are encoded in the Binary Coded Decimal

(BCD) format to simplify application use. Other registers are either bit-wise or standard

binary.

[1]

Except in the case of software reset, see Section 9.5.

Table 4.

Registers overview

Bit positions labelled as - are not implemented and will return a 0 when read. Bit positions labelled with N should always be

written with logic 0[1].

Address

Bit

Control and status registers

00h

Control_1

EXT_TEST

STOP

12_24

CIE

01h

Control_2

MSF

TI_TP

AIE

TIE

Time and date registers

02h

Seconds

SECONDS (0 to 59)

03h

Minutes

MINUTES (0 to 59)

04h

Hours

AMPM

HOURS (1 to 12) in 12 h mode

HOURS (0 to 23) in 24 h mode

05h

Days

DAYS (1 to 31)

06h

Weekdays

WEEKDAYS (0 to 6)

07h

Months

MONTHS (1 to 12)

08h

Years

YEARS (0 to 99)

Alarm registers

09h

Minute_alarm

AE_M

MINUTE_ALARM (0 to 59)

0Ah

Hour_alarm

AE_H

AMPM

HOUR_ALARM (1 to 12) in 12 h mode

HOUR_ALARM (0 to 23) in 24 h mode

0Bh

Day_alarm

AE_D

DAY_ALARM (1 to 31)

0Ch

Weekday_alarm

AE_W

WEEKDAY_ALARM (0 to 6)

Offset register

0Dh

Offset_register

MODE

OFFSET[6:0]

Timer registers

0Eh

Timer_clkout

COF[2:0]

CTD[1:0]

0Fh

Countdown_timer

COUNTDOWN_TIMER[7:0]

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