PCF8563_6

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 06 — 21 February 2008

9 of 32

NXP Semiconductors

PCF8563

Real-time clock/calendar

7.6.4 Alarm registers

When one or more of these registers are loaded with a valid minute, hour, day or weekday

and its corresponding bit Alarm Enable (AE) is logic 0, then that information will be

compared with the current minute, hour, day and weekday. When all enabled comparisons

first match, the Alarm Flag (AF) is set. AF will remain set until cleared by software.

Once AF has been cleared it will only be set again when the time increments to match the

alarm condition once more. Alarm registers which have their bit AE at logic 1 will be

ignored.

Table 14.

Month assignments

Month

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

January

C

x

x

00001

February

C

x

x

00010

March

C

x

x

00011

April

C

x

x

00100

May

C

x

x

00101

June

C

x

x

00110

July

C

x

x

00111

August

C

x

x

01000

September

C

x

x

01001

October

C

x

x

10000

November

C

x

x

10001

December

C

x

x

10010

Table 15.

Years - Years register (address 08h) bit description

Bit

Symbol

Value

Description

7 to 0

YEARS[7:0]

00 to 99

the current year, coded in BCD format

Table 16.

Minute_alarm - Minute alarm register (address 09h) bit description

Bit

Symbol

Value

Description

7

AE

0

minute alarm is enabled

1

minute alarm is disabled

6 to 0

ALARM _MINUTES[6:0]

00 to 59

the minute alarm information, coded in BCD

format

Table 17.

Hour_alarm - Hour alarm register (address 0Ah) bit description

Bit

Symbol

Value

Description

7

AE

0

hour alarm is enabled

1

hour alarm is disabled

6

x

not relevant

5 to 0

ALARM_HOURS[5:0]

00 to 23

the hour alarm information, coded in BCD format