mcf5208 Freescale Semiconductor, Inc, mcf5208 Datasheet - Page 29

• Manufacturer Part Number: mcf5208
• Description: Mcf5208 Coldfire Microprocessor Data Sheet
• Manufacturer: Freescale Semiconductor, Inc

5.8
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.
5.8.1
The following timing numbers indicate when data will be latched or driven onto the external bus, relative
to the memory bus clock, when operating in SDR mode on write cycles and relative to SD_DQS on read
cycles. The SDRAM controller is a DDR controller with an SDR mode. Because it is designed to support
DDR, a DQS pulse must remain supplied to the device for each data beat of an SDR read. The ColdFire
processor accomplishes this by asserting a signal called SD_SDR_DQS during read cycles. Take care
during board design to adhere to the following guidelines and specs with regard to the SD_SDR_DQS
signal and its usage.
Freescale Semiconductor
SDRAM Bus
BE/BWEn
SDR SDRAM AC Timing Characteristics
FB_CLK
FB_CSn
D[31:0]
A[23:0]
R/W
OE
TS
TA
MCF5208 ColdFire
FB1
FB2
Figure 15. Flexbus Write Timing
®
Microprocessor Data Sheet, Rev. 1
FB6
FB7
FB3
FB3
Electrical Characteristics
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