CHAPTER 6 BUS CONTROL
User’s Manual U14272EJ3V0UM
133
6.5.2 MEMCFG_REG (0x0A00 0304)
(1/2)
Bit
15
14
13
12
11
10
9
8
Name
Init
Reserved
Reserved
Reserved
B1Config1
B1Config0
Reserved
Bstreftype
R/W
R/W
R
R
R
R/W
R/W
R
R/W
At reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
Name
BstRefr
EDOAsym
Reserved
Reserved
Reserved
B0Config1
B0Config0
EDO/
SDRAM
R/W
R/W
R/W
R
R
R
R/W
R/W
R/W
At reset
0
0
0
0
0
0
0
0
Bit
Name
Function
15
Init
This bit is for SDRAM only. When software writes 1 to this bit, the memory
controller issues a SDRAM mode set command. After the SDRAM mode is set,
hardware automatically resets this bit to 0. When EDO DRAM is used, this bit
must not be set to 1.
14 to 12
Reserved
0 is returned when read
11, 10
B1Config(1:0)
Bank 1 capacity
00 : Bank 1 is not installed
01 : 16 Mbits
10 : 64 Mbits
11 : Reserved
9
Reserved
0 is returned when read
8
Bstreftype
Burst refresh type. This bit determines the number of CBR burst refresh cycles
executed before entering and exiting self-refresh mode.
0 : 8 rows refreshed
1 : All rows refreshed
7
BstRefr
Burst refresh enable. This bit enables or disables burst CBR refresh cycles when
entering or exiting self-refresh mode.
0 : Disable CBR burst refresh
1 : Enable CBR burst refresh
Burst and distributive CBR refresh are mixed if this bit is set to 1. For some kind of
DRAMs, mix use of burst and distributive CBR refresh may not be allowed.
6
EDOAsym
EDO DRAM configuration
0 : Asymmetrical
16 Mbit EDO DRAM : 12 rows by 8 columns
64 Mbit EDO DRAM : 13 rows by 9 columns
1 : Symmetrical
16 Mbit EDO DRAM : 10 rows by 10 columns
64 Mbit EDO DRAM : Setting prohibited
Содержание VR4181 mPD30181
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