fm3808 Ramtron Corporation, fm3808 Datasheet - Page 4

• Manufacturer Part Number: fm3808
• Description: 256kb Bytewide Fram W/ Real-time Clock
• Manufacturer: Ramtron Corporation

Table 1. Register Map
Rev. 1.3 (EOL)
Feb. 2006
Address
7FFFh
7FFEh
7FFDh
7FFCh
7FFBh
7FFAh
7FF9h
Address
7FF8h
Description
Timekeeping – Years
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.
Timekeeping – Months
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.
Timekeeping – Date of the month
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.
Timekeeping – Day of the week
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.
Timekeeping – Hours
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.
Timekeeping – Minutes
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.
Timekeeping – Seconds
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.
10 year.3
Description
Control-Nonvolatile
D7
D7
D7
D7
D7
D7
D7
OSCEN
0
0
0
0
0
0
D7
10 year.2
10 min.2
10 sec.2
Reserved
D6
D6
D6
D6
D6
D6
D6
0
0
0
0
D6
10 hours.1
10 year.1
10 date.1
10 min.1
10 sec.1
Reserved
D5
D5
D5
D5
D5
D5
D5
0
0
D5
10 hours.0
10 Month
10 date.0
10 year.0
10 min.0
10 sec.0
D4
D4
D4
D4
D4
D4
D4
0
CALS
D4
Seconds.3
Month.3
Hours.3
Date.3
Year.3
Min.3
D3
D3
D3
D3
D3
D3
D3
0
CAL.3
D3
Seconds.2
Month.2
Hours2
Year.2
Date.2
Min.2
Day.2
D2
D2
D2
D2
D2
D2
D2
CAL.2
D2
Seconds.1
Month.1
Hours.1
Year.1
Date.1
Day.1
Min.1
D1
D1
D1
D1
D1
D1
D1
CAL.1
D1
Seconds.0
Month.0
Hours.0
Year.0
Date.0
Day.0
Min.0
Page 4 of 27
CAL.0
D0
D0
D0
D0
D0
D0
D0
FM3808
D0