FM33256/FM3316 SPI Companion w/ FRAM
Register Map
The RTC and processor companion functions are accessed via 30 special function registers, which are mapped to
unique op-codes. The interface protocol is described on page 17. The registers contain timekeeping data, alarm
settings, control bits, and information flags. A description of each register follows the summary table.
Register Map Summary Table
Battery-backed =
Nonvolatile =
Address
1Dh
1Ch
1Bh
1Ah
19h
18h
17h
16h
15h
14h
13h
12h
11h
10h
0Fh
0Eh
0Dh
0Ch
0Bh
0Ah
09h
08h
07h
06h
05h
04h
03h
02h
01h
00h
D7
/Match
/Match
/Match
/Match
/Match
SNL
D6
0
0
0
D5
0
BB/NV User Programmable =
D2
D1
Alarm months
Alarm date
Alarm hours
Alarm minutes
Alarm seconds
FC
VTP1
D0
Function
Alarm Month
Alarm Date
Alarm Hours
Alarm Minutes
Alarm Seconds
Companion Control
Serial Number 7
Serial Number 6
Serial Number 5
Serial Number 4
Serial Number 3
Serial Number 2
Serial Number 1
Serial Number 0
Event Counter 1
Event Counter 0
Event Counter Control
Watchdog Control
Watchdog Control
Watchdog Restart
Watchdog Flags
Years
Month
Date
Day
Hours
Minutes
Seconds
CAL/Control
RTC/Alarm Control
00-99
01-12
01-31
01-07
00-23
00-59
00-59
Range
01-12
01-31
00-23
00-59
00-59
FFh
FFh
FFh
FFh
FFh
FFh
FFh
FFh
FFh
FFh
D4
D3
10 mo
10 date
Alarm 10 hours
Alarm 10 minutes
Alarm 10 seconds
AL/SW
F1
F0
VBC
Serial Number Byte 7
Serial Number Byte 6
Serial Number Byte 5
Serial Number Byte 4
Serial Number Byte 3
Serial Number Byte 2
Serial Number Byte 1
Serial Number Byte 0
Event Counter Byte 1
Event Counter Byte 0
-
-
-
-
-
WDSET4
-
-
WDST4
-
-
-
LWDF
POR
LB
10 years
0
0
10 mo
10 date
0
0
0
0
10 hours
0
10 minutes
10 seconds
-
CALS
CAL4
AF
CF
AEN
RC
WDET3
WDST3
WR3
-
VTP0
NVC
WDE
-
-
EWDF
0
0
0
0
0
0
-
/OSCEN
0
CAL3
reserved
WC
POLL
WDET2
WDET1
WDST2
WDST1
WR2
WR1
-
-
years
months
date
day
hours
minutes
seconds
CAL2
CAL1
CAL
W
CP
WDET0
WDST0
WR0
-
CAL0
R
Note: When the device is first powered up and programmed, all timekeeping registers must be written because the battery-
backed register values cannot be guaranteed. The table below shows the default values of the non-volatile registers and some of
the battery-backed bits. All other register values should be treated as unknown
.
Default Register Values
Address
1Dh
1Ch
1Bh
1Ah
19h
18h
17h
16h
15h
14h
13h
Hex Value
0x81
0x81
0x80
0x80
0x80
0x40
0x00
0x00
0x00
0x00
0x00
Address
12h
11h
10h
0Fh
0Eh
0Dh
0Ch
0Bh
01h
00h
Hex Value
0x00
0x00
0x00
0x00
0x00
0x01
0x00
0x00
0x00
0x80
Rev. 1.0
Dec. 2006
Page 12 of 28
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
