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M68HC12A4EVB Evaluation Board — Rev. 1
User’s Manual
MOTOROLA
Customizing the EPROMs
141
User’s Manual — M68HC12A4EVB Evaluation Board
Appendix E. Customizing the EPROMs
The following blocks in the factory-supplied EPROMs can be reprogrammed
with user code or D-Bug12 code that has been modified for custom operation:
•
$8000–$9FFF — Available for user programs
•
$FD80–$FDFF — D-Bug12 startup code. See
Appendix C. D-Bug12
Startup Code
.
•
$FE80–$FEFF — D-Bug12 customization data. See
Appendix D.
D-Bug12 Customization Data
.
•
$FF00–$FFBF — Available for user programs
Since the EPROMs also contain D-Bug12 and other EVB operating firmware,
the factory programming must be retained and burned into the custom chips
along with the custom code.
Table E-1
maps the EVB’s logical addresses (from
Table 3-5. Factory-Configuration Memory Map
) to the pin-level physical
addresses of U7 and U9A.
Note that the lower half of each EPROM — from $0000 to $3FFF — is unused
and is filled with 1s. This is necessary because of the chip select, CSP0, used by
the MCU for EPROM access. For more information on this subject, refer to
4.7.2 Chip Selects
.
NOTE:
Do not reprogram the factory-supplied EPROMs. Keep them as masters, using
expendable chips for new programming.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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