Datasheet

Philips Semiconductors

PCF8563

Real time clock/calendar

Product data Rev. 04 — 12 March 2004 9 of 30

9397 750 12999

[1] These bits may be re-assigned by the user.

8.6.4 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.

Thursday xxxxx100

Friday xxxxx101

Saturday xxxxx110

Table 14: Weekday assignments

…continued

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

Table 15: Months/century (address 07H) bits description

Bit Symbol Value Description

7 century

[1]

this bit is toggled when the years register overﬂows from 99 to 00

0 indicates the century is 20xx

1 indicates the century is 19xx

4 to 0 month 01 to 12 this register holds the current month coded in BCD format, see Tabl e 16

Table 16: Month assignments

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

January Cxx00001

February Cxx00010

March C x x 00011

April Cxx00100

May Cxx00101

June Cxx00110

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 17: 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