Philips Semiconductors

PCF8563

Real-time clock/calendar

Product specification

16 April 1999

10 of 30

9397 750 04855

© Philips Electronics N.V. 1999. All rights reserved.

8.6.5

Alarm registers

When one or more of the alarm registers are loaded with a valid minute, hour, day or

weekday and its corresponding AE (Alarm Enable) bit is a logic 0, then that

information will be compared with the current minute, hour, day and weekday. When

all enabled comparisons first match, the bit AF (Alarm Flag) 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 AE bit set at logic 1 will be ignored.

Table 19: Minute alarm register bits description (address 09H)

Bit

Symbol

Description

7

AE

AE = 0; minute alarm is enabled. AE = 1; minute alarm is disabled.

6 to 0 <minute alarm>

These bits represents the minute alarm information coded in BCD

format; value = 00 to 59.

Table 20: Hour alarm register bits description (address 0AH)

Bit

Symbol

Description

7

AE

AE = 0; hour alarm is enabled. AE = 1; hour alarm is disabled.

6 to 0 <hour alarm>

These bits represents the hour alarm information coded in BCD

format; value = 00 to 23.

Table 21: Day alarm register bits description (address 0BH)

Bit

Symbol

Description

7

AE

AE = 0; day alarm is enabled. AE = 1; day alarm is disabled.

6 to 0 <day alarm>

These bits represents the day alarm information coded in BCD

format; value = 01 to 31.

Table 22: Weekday alarm register bits description (address 0CH)

Bit

Symbol

Description

7

AE

AE = 0; weekday alarm is enabled.

AE = 1; weekday alarm is disabled.

6 to 0 <weekday alarm>

These bits represents the weekday alarm information

value0to6.