PCF8563_6

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 06 — 21 February 2008

10 of 32

NXP Semiconductors

PCF8563

Real-time clock/calendar

7.6.5 Clock output control register

7.6.6 Countdown timer

The timer register is an 8-bit binary countdown timer. It is enabled and disabled via the

timer control register bit TE. The source clock for the timer is also selected by the timer

control register. Other timer properties such as interrupt generation are controlled via

operating at a frequency of at least twice the selected timer clock.

Table 18.

Day_alarm - Day alarm register (address 0Bh) bit description

Bit

Symbol

Value

Description

7

AE

0

day alarm is enabled

1

day alarm is disabled

6

x

not relevant

5 to 0

ALARM_DAYS[5:0]

01 to 31

the day alarm information, coded in BCD format

Table 19.

Weekday_alarm - Weekday alarm register (address 0Ch) bit description

Bit

Symbol

Value

Description

7

AE

0

weekday alarm is enabled

1

weekday alarm is disabled

6 to 3

x

not relevant

2 to 0

ALARM_

WEEKDAYS[2:0]

0 to 6

the weekday alarm information, coded in BCD

format

Table 20.

CLKOUT_control - CLKOUT control register (address 0Dh) bit description

Bit

Symbol

Value

Description

7

FE

0

the CLKOUT output is inhibited and set to

high-impedance

1

the CLKOUT output is activated

6 to 2

x

not relevant

1 to 0

FD[1:0]

see Table 21

these bits control the frequency output at

pin CLKOUT

Table 21.

FD1 and FD0: CLKOUT frequency selection

FD1

FD0

CLKOUT frequency

0

0

32.768 kHz

0

1

1024 Hz

1

0

32 Hz

11

1 Hz