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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
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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
CS
3
Figure 7-5 (1) shows the interface timing for 2WE DRAM. Figure 7-5 (2) shows the interface
timing for 2CAS DRAM.
Read cycle
ø
Address
Row
bus
CS
3
RAS
(
)
RD
CAS
(
)
HWR
UW
(
)
LWR
LW
(
)
RFSH
AS
Note:
16-bit access
*
Figure 7-5 DRAM Control Signal Output Timing (1) (2WE Mode)
CAS/WE = 0 (2WE Mode)
UW
LW
CAS
RAS
Write cycle
Column
Row
160
DRAM Pin
CAS/WE = 1 (2CAS Mode)
UCAS
LCAS
WE
RAS
Refresh cycle
*
Column
Area 3 top address
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