Data Sheet

Product data sheet Rev. 05 — 17 July 2007 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.

July Cxx00111

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 (address 08h) bits description

Bit Symbol Value Description

7 to 0 YEARS 00 to 99 this register holds the current year coded in BCD format

Table 14. Month assignments

…continued

Month Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Table 16. Minute alarm (address 09h) bits description

Bit Symbol Value Description

7 AE 0 minute alarm is enabled

1 minute alarm is disabled

6 to 0 ALARM

_MINUTES

00 to 59 this register holds the minute alarm information coded in BCD

format

Table 17. Hour alarm (address 0Ah) bits description

Bit Symbol Value Description

7 AE 0 hour alarm is enabled

1 hour alarm is disabled

5 to 0 ALARM_

HOURS

00 to 23 this register holds the hour alarm information coded in BCD

format

Table 18. Day alarm (address 0Bh) bits description

Bit Symbol Value Description

7 AE 0 day alarm is enabled

1 day alarm is disabled

5 to 0 ALARM_

DAYS

01 to 31 this register holds the day alarm information coded in BCD format