PCA2125_1

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 01 — 28 July 2008

9 of 36

NXP Semiconductors

PCA2125

SPI Real-time clock/calendar

[1]

The RTC compensates for leap years by adding a 29th day to February if the year counter contains a value

which is exactly divisible by 4, including the year 00.

[1]

The weekday assignments can be re-defined by the user.

Table 12.

Register Days (address 05h) bit description

Bit

Symbol

Value

Description

6, 7

-

0

unused

5 to 0

DAYS[5:0]

01 to 31

this register holds the current day value coded in BCD

format[1]

Table 13.

Register Weekdays (address 06h) bit description

Bit

Symbol

Value

Description

3 to 7

-

0

unused

2 to 0

WEEKDAYS[2:0]

0 to 6

this register holds the current weekday value; see

Table 14

Table 14.

Weekday assignments

Day[1]

Double-digit

Digit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Sunday

X

XXXX

0

0

0

Monday

X

XXXX

0

0

1

Tuesday

X

XXXX

0

1

0

Wednesday

X

XXXX

0

1

1

Thursday

X

XXXX

1

0

0

Friday

X

XXXX

1

0

1

Saturday

X

XXXX

1

1

0

Table 15.

Register Months (address 07h) bit description

Bit

Symbol

Value

Description

5 to 7

-

0

unused

4 to 0

MONTHS[4:0]

01 to 12

this register holds the current month value coded in BCD

format; see Table 16

Table 16.

Month assignments

Month

Double-digit

Digit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

January

X

X

X

00001

February

X

X

X

0

0

0

1

0

March

X

X

X

0

0

0

1

1

April

X

X

X

0

0

1

0

0

May

X

X

X

00101

June

X

X

X

0

0

1

1

0

July

X

X

X

0

0

1

1

1

August

X

X

X

0

1

0

0

0

September

X

X

X

0

1

0

0

1