Figure 7-5 DRAM Control Signal Output Timing (2) (2CAS Mode)
Refresh Cycle Priority Order: When there are simultaneous bus requests, the priority order is:
(High)
External bus master > refresh controller > DMA controller > CPU
(Low)
For details see section 6.3.7, Bus Arbiter Operation.
Wait State Insertion: When bit AST3 is set to 1 in ASTCR, bus controller settings can cause wait
states to be inserted into bus cycles and refresh cycles. For details see section 6.3.5, Wait Modes.
ø
( )
CS
RAS
3
( )
HWR
UCAS
( )
LWR
LCAS
( )
RD
WE
RFSH
AS
Read cycle
Write cycle
Refresh cycle
*
Row
Column
Row
Column
Area 3 top address
Note: 16-bit access
*
Address
bus
161
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