AN2008 Motorola / Freescale Semiconductor, AN2008 Datasheet - Page 2

• Manufacturer Part Number: AN2008
• Description: Evaluating ColdFire in a 68K Target System: MCF5307 to MC68EC020 Gateway Reference Design
• Manufacturer: Motorola / Freescale Semiconductor

The Gateway reference design which will be discussed is an integrated circuit board which will bridge an
existing MC68EC020 system to the ColdFire MCF5307 microprocessor, to evaluate the ease of upgrading
to 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 a customer’s
system code to the ColdFire architecture in situ as opposed to the traditional method of initially porting code
to an evaluation platform. This paper is intended to describe the use and operation of the Gateway board.
In using the Gateway solution, the 68K processor initialization code has to be configured to run on the
internal register map of the ColdFire processor. Although the ColdFire architecture is derived from the
680x0 family with a simplified set of instructions and addressing modes, assembler programs while
straightforward to port to ColdFire may require some modification before they will run. To help customers
with this translation process, Motorola has funded the development of an assembler code converter -
PortASM/68K, written by MicroAPL Ltd. in the U.K.
(Consult
http://www.mot.com/SPS/HPESD/tools/companion.html
for more information.)
This utility will run on either PC’s (under DOS, Windows 3.x, Windows95/98 & Windows NT) or Sun
Workstations (under SunOS or Solaris) and is available free of charge via download from the web. This
converter not only converts the 68K assembler code to ColdFire assembler but analyses how the original
code operates allowing the analyzer to produce optimized ColdFire code in two passes, rather than just a
straight translation.
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MCF5307 to MC68EC020 Gateway Reference Design