FM30C256

Rev 2.1

Dec. 2002

Page 4 of 18

Table 1. Register Map

Address

Description

8h

Timekeeping – Years

D7

D6

D5

D4

D3

D2

D1

D0

10 year.3

10 year.2

10 year.1

10 year.0

Year.3

Year.2

Year.1

Year.0

Contains the lower two BCD digits of the year. Lower nibble contains the value for years; upper nibble

contains the value for 10s of years. Each nibble operates from 0 to 9. The range for the register is 0-99.

7h

Timekeeping – Months

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

10 Month

Month.3

Month.2

Month.1

Month.0

Contains the BCD digits for the month. Lower nibble contains the lower digit and operates from 0 to 9;

upper nibble (one bit) contains the upper digit and operates from 0 to 1. The range for the register is 1-12.

6h

Timekeeping – Date of the month

D7

D6

D5

D4

D3

D2

D1

D0

0

0

10 date.1

10 date.0

Date.3

Date.2

Date.1

Date.0

Contains the BCD digits for the date of the month. Lower nibble contains the lower digit and operates

from 0 to 9; upper nibble contains the upper digit and operates from 0 to 3. The range for the register is 1-

31.

5h

Timekeeping – Day of the week

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

0

0

Day.2

Day.1

Day.0

Lower nibble contains a value that correlates to day of the week. Day of the week is a ring counter that

counts from 1 to 7 then returns to 1. The user must assign meaning to the day value, as the day is not

integrated with the date.

4h

Timekeeping – Hours

D7

D6

D5

D4

D3

D2

D1

D0

0

0

10 hours.1

10 hours.0

Hours.3

Hours2

Hours.1

Hours.0

Contains the BCD value of hours in 24-hour format. Lower nibble contains the lower digit and operates

from 0 to 9; upper nibble (two bits) contains the upper digit and operates from 0 to 2. The range for the

register is 0-23.

3h

Timekeeping – Minutes

D7

D6

D5

D4

D3

D2

D1

D0

0

10 min.2

10 min.1

10 min.0

Min.3

Min.2

Min.1

Min.0

Contains the BCD value of minutes. Lower nibble contains the lower digit and operates from 0 to 9;

upper nibble contains the upper minutes digit and operates from 0 to 5. The range for the register is 0-59.

2h

Timekeeping – Seconds

D7

D6

D5

D4

D3

D2

D1

D0

0

10 sec.2

10 sec.1

10 sec.0

Seconds.3

Seconds.2

Seconds.1

Seconds.0

Contains the BCD value of seconds. Lower nibble contains the lower digit and operates from 0 to 9;

upper nibble contains the upper digit and operates from 0 to 5. The range for the register is 0-59.