
MFC2000 Multifunctional Peripheral Controller 2000
Hardware Description
4-62
Conexant
100723A
Bit 4:
Bank 0 Increase RAS Cycle Time
This register will add one cycle after the refresh cycle prior to RAS
precharge to meet T
RC
(RASn cycle time). This is needed in order to
use 70 ns DRAMs while running at 39MHz.
Bit 3:
Bank 0 2-cycle RAS Precharge
This register will increase the RASn[0] Precharge time from 1 to 2
clock cycles.
Bit 2:
Bank 0 1-cycle RAH
This register will increase the RASn[0] address hold time. When this
bit is set, the address will be multiplexed 1 clock cycle after the falling
edge of RAS[0]n. The default setting will multiplex the row/column
address clock cycle after the falling edge of RAS[1]n.
Bits 1-0:
Bank 0 Speed Control
These registers will control the speed of the DRAM interface for bank
0 when in the non-interleaved mode. This register controls the width of
the CASn signal. These bits are ignored in interleaved mode.
Bit 1
Bit 0
Non-Interleaved Operation
0
0
CASn is clock cycle wide.
0
1
CASn is 1 clock cycle wide.
1
0
CASn is 2 clock cycles wide for Read
and 1 clock cycle wide for write.
1
1
N/A
Address
Backup
Configuration
Register
(BackupConfig)
$01FF8099
Bit 15
(Not Used)
Bit 14
(Not Used)
Bit 13
Internal
Power Down
Select
Bit 12
Batrstn
Detected
Bit 11
Lockenn
Timeout
Detected
Bit 10
SRAM
Enable
0 = disable
1 = enable
Bit 9
Bit 8
Default
Rst. Value
xxxxx000b
Read Value
00h
Bank 1
Data
interface
size:
0 = 8-bit
1 = 16-bit
Bank 0
Data
interface
size:
0 = 8-bit
1 = 16-bit
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
interleaved
1 = 2 way
interleaved
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 tri-stated.
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:
Bit 13:
Not used
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