HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 224

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 6 Bus Controller
•
Rev.6.00 Sep. 27, 2007 Page 194 of 1268
REJ09B0220-0600
To select RAS up mode, clear the RCDM bit in MCR to 0. 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 6.22 shows an example of the timing in
RAS up mode.
In the case of burst ROM space access, the RAS signal is not restored to the high level.
RAS up mode
CAS, LCAS
Note: n = 2 to 5
CSn (RAS)
D
A
15
23
to D
to A
φ
0
0
Figure 6.22 Example of Operation Timing in RAS Up Mode
T
p
DRAM access
T
r
T
c1
T
c2
DRAM access
T
c1
T
c2
External space
T
1
access
T
2