
Hardware Description
MFC 2000 Multifunctional Peripheral Controller 2000
100723A
Conexant
5-7
5.1.6 Register Description
Battery Backup and Prime Power Reset Registers
Name/Address
Bit 15
(Not Used) (Not Used) Internal
Bit 14
Bit 13
Bit 12
Battery
Reset
Flag
Bit 11
Bit 10
SRAM
Enable
0 = disable
1 = enable
Bit 9
Bit 8
Default
Rst. Value
xxx00000b
Read Value
00h
Backup
Configuration
Register
(BackupConfig)
$01FF8099
Power
Down
Select
Lockout
Time-out
Flag
Bank 1
Data
interface
size:
0 = 8-bit
1 = 16-bit
Bank 0
Data
interface
size:
0 = 8-bit
1 = 16-bit
Name/Address
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Default
Backup
Configuration
Register
(BackupConfig)
$01FF8098
DRAM Backup Time
0 = no backup
1 = 1-2 days
2 = 2-3 days
3 = infinite days
Refresh
Rate
0 = normal
1 = slow
Oscillator
Speed
0 =
32.768
KHz
1 =
65.536
KHz
Bank 1
Enable
0 = disable
1 = enable
Bank 0
Enable
0 = disable
1 = enable
Bank 1
Interleave
Enable
0 = non
interleaved
1 = 2 way
interleaved
Bank 0
Interleave
Enable
0 = non
interleave
d
1 = 2 way
interleave
d
Rst. Value
00h
Read Value
00h
Register Description: This register is set to all zeros when first powered up and is battery backed up with the RTC
Battery during power down. When a time out condition occurs, the RASn and CASn signals are tristated. When
prime power has returned from a power down sequence, the user will have to perform a checksum on the DRAM
data to know if a time out has occurred since there is no indication that the DRAM battery has lost power. The
user will have to wait 1ms before accessing the DRAM after prime power has returned.
Bits 15-14:Not used
Bits 13:
Internal Power Down Select
0 = PWRDWNn is generated by or-ing power_down1 with
power_down2
1= PWRDWNn is generated by and-ing power_down1 with
power_down2
Note
: Power_down1 and power_down2 are output signals from the power-down detection circuit
1 and 2.
Bit12:
Battery Reset Flag
This bit indicates that a BATRSTn occurred. To clear this bit, a 1 must
be written to this bit.
This bit indicates that a power down occurred, but no lockout was set
with in the 1-2 second period. The lockout timer initiated the
LOCKENn to create the lockout condition. Once the lockout condition
occurs, if the power down signal is high, the chip will come out of reset
after a PUD1 delay. To clear this bit, a 1 must be written to this bit.
This bit enables the SRAM chip select CSN0.
This register defines whether the databus to the bank 1 DRAMs is 8
bits wide or 16 bits wide. An 8-bit wide DRAM interface uses RASn[1]
and CASOn[0]. A 16-bit wide non-interleaved DRAM interface uses
RASn[1] and CASOn[1:0]. A 16-bit wide interleaved DRAM interface
uses RASn[1], CASEn[1:0], and CASOn[1:0].
Bit11:
Lockout Time-out Flag
Bit10:
Bit 9:
SRAM Chip Select Enable
Bank 1 Interface Size