fm3316 Ramtron Corporation, fm3316 Datasheet - Page 16

• Manufacturer Part Number: fm3316
• Description: 3v Integrated Processor Companion With Memory
• Manufacturer: Ramtron Corporation

Rev. 1.1
Dec. 2007
09h
EWDF
LWDF
POR
LB
08h
07h
06h
05h
04h
03h
Watchdog Flags
Early Watchdog Timer Fault Flag: When a watchdog restart occurs too early (before the programmed watchdog
StartTime), the /RST pin is driven low and this flag is set. It must be cleared by the user. Note that both EWDF
and POR could be set if both reset sources have occurred since the flags were cleared by the user. Battery-
backed, read/write.
Late Watchdog Timer Fault Flag: When either a watchdog restart occurs too late (after the programmed
watchdog EndTime) or no restart occurs, the /RST pin is driven low and this flag is set. It must be cleared by the
user. Note that both LWDF and POR could be set if both reset sources have occurred since the flags were
cleared by the user. Battery-backed, read/write.
Power-On Reset: When the /RST signal is activated by V
will not set this flag. Note that one or both of the watchdog flags and the POR flag could be set if both reset
sources have occurred since the flags were cleared by the user. Battery-backed, read/write. (internally set, user
must clear bit)
Low Backup: If the V
V
values should be treated as unknown. The user should clear it to 0 when initializing the system. Battery-backed.
Read/Write (internally set, user must clear bit).
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. Battery-backed,
read/write.
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. Battery-
backed, read/write.
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. Battery-
backed, read/write.
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. Battery-backed, read/write.
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.
Battery-backed, read/write.
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. Battery-backed,
read/write.
10 year.3
EWDF
DD
D7
D7
D7
D7
D7
D7
D7
0
0
0
0
<V
0
BAK
, this bit will be set to ‘1’. All registers need to be re-initialized since the battery-backed register
10 year.2
10 min.2
LWDF
D6
D6
D6
D6
D6
D6
D6
0
0
0
0
BAK
source drops to a voltage level insufficient to operate the RTC/alarm when
10 hours.1
10 year.1
10 date.1
10 min.1
POR
D5
D5
D5
D5
D5
D5
D5
0
0
10 hours.0
10 Month
10 year.0
10 date.0
10 min.0
D4
LB
D4
D4
D4
D4
D4
D4
0
DD
Month.3
Hours.3
FM33256/FM3316 SPI Companion w/ FRAM
Year.3
Date.3
Min.3
< V
D3
D3
D3
D3
D3
D3
D3
0
-
TP
, the POR bit will be set to 1. A manual reset
Month.2
Hours2
Year.2
Date.2
Day.2
Min.2
D2
D2
D2
D2
D2
D2
D2
-
Month.1
Hours.1
Date.1
Year.1
Day.1
Min.1
D1
D1
D1
D1
D1
D1
D1
-
Page 16 of 28
Month.0
Hours.0
Date.0
Year.0
Day.0
Min.0
D0
D0
D0
D0
D0
D0
D0
-