mcf5407 Freescale Semiconductor, Inc, mcf5407 Datasheet - Page 298

• Manufacturer Part Number: mcf5407
• Description: Mcf5407 Coldfire Integrated Microprocessor User
• Manufacturer: Freescale Semiconductor, Inc

Synchronous Operation
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
Figure 11-21 shows a write followed by a read in continuous page mode. Because the bus
cycle is terminated with a
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.
11-30
Figure 11-20. Synchronous, Continuous Page-Mode Access—Consecutive Reads
RAS[0] or [1]
• If the next bus cycle is pending and hits in the page, the page is left open, and the
CAS[3:0]
DRAMW
D[31:0]
A[31:0]
CLKIN
SRAS
SCAS
next SDRAM access begins with a
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.
ACTV
ACTV
t
RCD
Row
= 2
NOP
command.
WRITE
READ
t
CASL
command, the second cycle begins sooner after the write
MCF5407 User’s Manual
= 2
Column
READ
NOP
or
WRITE
command. Because of the nature
READ
t
CASL
Column
= 2
NOP
t
NOP
EP
PALL