MC68EN302 PRODUCT INFORMATION
MODULE BUS CONTROLLER
The MC68EN302 module bus controller provides basic interface capabilities to the module bus as well as basic
system responsibilities. The features of the module bus controller are:
• Interface Between Internal 68000 bus and the Module Bus.
• Provision for Dynamic Bus Sizing, Using the Chip Select Logic of the 68302 Core.
• Handling of Interrupts for the Ethernet Controller and DRAM Controller.
• Coordination of Bus Mastership from External Sources, the Module Bus, and the MC68EN302 Core.
Figure 3. BusStructure
DRAM CONTROLLER
• Provides two CAS lines
• Provides two RAS lines (two banks supported)
• DRAM address multiplexing on standard address bus
• Programmable up to three wait states
• 100 nS DRAM for zero wait states at 20 MHz
• 80 nS DRAM for zero wait states at 25 MHz
• CAS before RAS refresh and refresh support during system reset
MC68EN302
MODULE
BUS
CONTROLLER
ETHERNET AND
MODULE BUS
68000 BUS
P
A
D
S
INTERNAL
68000 BUS
EXTERNAL
302 BUS
INTERNAL
B
U
F
F
E
R
S
DRAM CONTROLLER
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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