SH7751 Group, SH7751R Group
Section 13 Bus State Controller (BSC)
R01UH0457EJ0301 Rev. 3.01
Page 413 of 1128
Sep 24, 2013
13.3.4
DRAM Interface
Direct Connection of DRAM:
When the memory type bits (DRAMTP2–0) in BCR1 are set to
100, area 3 becomes DRAM interface. The DRAM interface function can then be used to connect
DRAM to this LSI.
16 or 32 bits can be selected as the interface data width.
2-CAS 16-bit DRAMs can be connected, since
CAS
is used to control byte access.
Signals used for connection are
CS3
,
RAS
,
CAS0
to
CAS3
, and RD/
WR
.
CAS2
to
CAS3
are not
used when the data width is 16 bits.
In addition to normal read and write access modes, fast page mode is supported for burst access.
EDO mode, which enables the DRAM access time to be increased, is supported.
A10
A2
RAS
CS3
RD/
WR
D31
D16
CAS3
CAS2
D15
D0
CAS1
CAS0
SH7751/SH7751R
256K
×
16-bit
DRAM
A8
A0
RAS
OE
WE
I/O15
I/O0
UCAS
LCAS
A8
A0
RAS
OE
WE
I/O15
I/O0
UCAS
LCAS
••••
••••
••••
••••
••••
••••
••••
••••
••••
••••
••••
••••
••••
••••
Figure 13.13 Example of DRAM Connection (32-Bit Data Width, Area 3)