Datasheet

11-30 MCF5407 User’s Manual
Synchronous Operation
• If the next bus cycle is pending and hits in the page, the page is left open, and the
next SDRAM access begins with a
READ or WRITE command. Because of the nature
of the internal CPU pipeline this condition does not occur often, however, the use of
continuous page mode is recommended because it can provide a slight performance
increase.
Figure 11-20 shows two read accesses in continuous page mode. Note that there is no
precharge between the two accesses. Also notice that the second cycle begins with a read
operation with no
ACTV command.
Figure 11-20. Synchronous, Continuous Page-Mode Access—Consecutive Reads
Figure 11-21 shows a write followed by a read in continuous page mode. Because the bus
cycle is terminated with a
WRITE command, the second cycle begins sooner after the write
than after the read. A read requires data to be returned before the bus cycle can terminate.
Note that in continuous page mode, secondary accesses output the column address only.
A[31:0]
SRAS
SCAS
DRAMW
D[31:0]
ACTV NOP READNOP
RAS[0] or [1]
CAS
[3:0]
READ NOP
NOP
PALL
t
CASL
= 2
t
RCD
= 2
t
CASL
= 2
t
EP
Row Column Column
CLKIN