HD6433044 Datasheet, PDF (174/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

2CAS and 2WE Modes: The CAS/WE bit in RFSHCR can select two control modes for 16-bit-
wide DRAM: one using UCAS and LCAS; the other using UW and LW. These DRAM pins
correspond to H8/3048 Series pins as shown in table 7-6.
Table 7-6 DRAM Pins and H8/3048 Series Pins
H8/3048 Series Pin
HWR
LWR
RD
CS₃
CAS/WE = 0 (2WE Mode)
UW
LW
CAS
RAS
DRAM Pin
CAS/WE = 1 (2CAS Mode)
UCAS
LCAS
WE
RAS
Figure 7-5 (1) shows the interface timing for 2WE DRAM. Figure 7-5 (2) shows the interface
timing for 2CAS DRAM.
Read cycle
Write cycle*
Refresh cycle
ø
Address
bus
CS ₃
(RAS )
RD
(CAS )
HWR
(UW )
LWR
(LW )
RFSH
Row
Column
Row
Column
Area 3 top address
AS
Note: * 16-bit access
Figure 7-5 DRAM Control Signal Output Timing (1) (2WE Mode)
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