169
T
p
Address bus
ø
RD
RAS
HWR
UCAS
,
LCAS
External read
Idle cycle
Data bus
T
r
T
c1
T
c2
T
1
DRAM space write
DRAM space read
T
2
T
c2
T
3
T
i
T
c1
Figure 4.49 Example of Idle Cycle Operation in RAS Down Mode (2)
(Read after Write) (IDLC = 0, RAST = 0, CAST = 0)
Idle Cycle in Case of Normal Space Access after DRAM Space Access: While the DRMI bit is
cleared to 0 in the DRACCR register, idle cycle insertion after DRAM space access is disabled.
Idle cycle insertion after DRAM space 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 are valid. Figures 4.50 and 4.51 show examples of idle cycle
operation when the DRMI bit is set to 1.
When the DRMI bit is cleared to 0, an idle cycle is not inserted after DRAM space access even if
bits ICIS1 and ICIS0 are set to 1.
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