MCF5480 Freescale Semiconductor, Inc, MCF5480 Datasheet - Page 15

• Manufacturer Part Number: MCF5480
• Description: Mcf548x Coldfire Microprocessor
• Manufacturer: Freescale Semiconductor, Inc

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The SDRAM controller supports accesses to main SDRAM memory from any internal master. It supports standard SDRAM or
double data rate (DDR) SDRAM, but it does not support both at the same time. The SDRAM controller uses SSTL2 and SSTL3
I/O drivers. Both SSTL drive modes are programmable for Class I or Class II drive strength.
9.1
The following timing numbers indicate when data is latched or driven onto the external bus, relative to the memory bus clock,
when operating in SDR mode on write cycles and relative to SDR_DQS on read cycles. The MCF548x SDRAM controller is a
DDR controller that has an SDR mode. Because it is designed to support DDR, a DQS pulse must be supplied to the MCF548x
for each data beat of an SDR read. The MCF548x accomplishes this by asserting a signal called SDR_DQS during read cycles.
Care must be taken during board design to adhere to the following guidelines and specs with regard to the SDR_DQS signal
and its usage.
Freescale Semiconductor
SDRAM Bus
SDR SDRAM AC Timing Characteristics
FBCSn, BE/BWEn
TSIZ[1:0]
AD[31:Y]
AD[X:0]
CLKIN
R/W
ALE
OE
TA
MCF548x ColdFire
Figure 12. FlexBus Write Timing
FB1
A[31:Y]
FB2
FB6
®
Microprocessor, Rev. 4
TSIZ[1:0]
A[X:0]
DATA
FB7
FB3
FB3
SDRAM Bus
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