h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 168

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

• RAS Up Mode
Rev. 2.00, 03/04, page 136 of 534
To select RAS up mode, clear the RCDM bit to 0 in DRAMCR. Each time access to DRAM
space is interrupted and another space is accessed, the RAS signal goes high again. Burst
operation is only performed if DRAM space is continuous. Figure 6.35 shows an example of
the timing in RAS up mode.
φ
Address bus
Data bus
Figure 6.35 Example of Operation Timing in RAS Up Mode (RAST = 0, CAST = 0)
(
(
(
,
)
)
)
T
Row address
p
DRAM space read
T
r
Column address 1 Column address 2
T
c1
T
c2
High
T
DRAM space
c1
read
T
c2
External address
Normal space
T
1
read
T
2