Datasheet

Section 6 Bus Controller
Rev.6.00 Sep. 27, 2007 Page 194 of 1268
REJ09B0220-0600
• RAS up mode
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.
CSn (RAS)
CAS, LCAS
External space
access
T
p
A
23
to A
0
φ
D
15
to D
0
T
r
T
c1
T
c2
T
c1
T
c2
DRAM accessDRAM access
T
1
T
2
Note: n = 2 to 5
Figure 6.22 Example of Operation Timing in RAS Up Mode