Philips Semiconductors

PCA8565

Real time clock/calender

Product data

Rev. 01 — 31 March 2003

8 of 26

9397 750 10695

© Koninklijke Philips Electronics N.V. 2003. All rights reserved.

[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

xxxxx1

0

0

Friday

xxxxx1

0

1

Saturday

xxxxx1

1

0

Table 14:

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 Table 16

Table 16:

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 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