Datasheet

Section 6 Bus Controller (BSC)
Rev.7.00 Mar. 18, 2009 page 261 of 1136
REJ09B0109-0700
• Normal space access after DRAM space write access
While the ICIS2 bit is set to 1 in BCR and a normal space read access occurs after DRAM
space write access, idle cycle is inserted in the first read cycle. The number of states of the idle
cycle to be inserted is in accordance with the setting of the IDLC bit. It does not depend on the
DRMI bit in DRACCR. Figure 6.78 shows an example of idle cycle operation when the ICIS2
bit is set to 1.
T
p
Address bus
φ
RD
RAS
HWR, LWR
U
CAS, LCAS
External space read
Idle cycle
Data bus
T
r
T
c1
T
c2
T
1
DRAM space readDRAM space read
T
2
T
c2
T
3
T
i
T
c1
Figure 6.78 Example of Idle Cycle Operation after DRAM Write Access
(IDLC = 0, ICIS1 = 0, RAST = 0, CAST = 0)
Idle Cycle in Case of Normal Space Access after Continuous Synchronous DRAM Space
Access:
Note: In the H8S/2378 Group, the synchronous DRAM interface is not supported.
• Normal space access after a continuous synchronous DRAM space read access
While the DRMI bit is cleared to 0 in DRACCR, idle cycle insertion after continuous
synchronous DRAM space read access is disabled. Idle cycle insertion after continuous
synchronous DRAM space read access can be enabled by setting the DRMI bit to 1. The
conditions and number of states of the idle cycle to be inserted are in accordance with the
settings of bits ICIS1, ICIS0, and IDLC in RCR. Figure 6.79 shows an example of idle cycle
operation when the DRMI bit is set to 1. When the DRMI bit is cleared to 0, an idle cycle is