MOTOROLA
GATEWAY BOARD
1
THE MOTOROLA GATEWAY BOARD
(MCF5202 Microprocessor To MC68EC000 Bus Interface Card)
Jeff Miller
October 15, 1997
1.0 Introduction
The integrated Gateway circuit board will bridge an existing MC68EC000 system to the new ColdFire¨
MCF5202 VL-RISC microprocessor, to evaluate the possibility of moving toward a higher performance architecture.
It can be used to evaluate system enhancements such as on-chip instruction and/or data cache and bursting to external
memory. It can also be used to port software code to the ColdFire architecture directly in a customerÕs system as
opposed to the traditional method of porting code to an evaluation platform. This paper describes the use and opera-
tion of the Gateway board as well as technical information that can be used as a reference design.
2.0 Gateway Board Overview
2.1 Software Considerations
The principal use of this board is to help port system software code from the M68000 architecture to the Cold-
Fire architecture. Users will have to recompile the system software to target the MCF5202 instead of targeting the
M68000. Even though the system will see a hardware interface that looks like a MC68EC000, the software must con-
sist of ColdFire instructions for the MCF5202 to work properly. Refer to Section 8, ÒPorting from M68K Architec-
ture,Ó of the
MCF5202 UserÕs Manual
for an overview of the issues encountered when upgrading from the M68000 to
the ColdFire microprocessor. In addition, youÕll have to keep three key things in mind while porting system software
code from the MC68EC000 system to the MCF5202 system
1.
mapping 32-bit MCF5202 addresses to 24-bit 68EC000 addresses
2.
cache coherency
3.
RMW cycles
MICROPROCESSORS
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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