James Humes wrote:
> Are there any suggestions for fixing this in a way other than my
> insertion of NOPs method?

Yes.  Your method got you into trouble because it tried to do a dumb edit on
the HEX file instead of interpreting it properly, making modifications, then
writing it back out.  There are many legal ways the HEX file can be written
that can be different at the low level syntax.

Another point is that it would be best to put RETLW h'FF' in the source code
with an appropriate comment what the value means and that it will be filled
in during production test.  That would also give you the option of modifying
the value in place after the programming step in case that is more
convenient.  I use this method for a current customer.  The firmware is
first programmed into the device because it needs to run in order to collect
the data for calibration.  Once the data is collected, the FFh is
overwritten with the computed value without reprogramming the device.  You
can always flip 1 bits to 0 but going the other way requires an erase
operation, often on more than a single memory location.  The source code
specifies FFh because that is the erased state.

If you can determine calibration values up front, then making a temporary
custom HEX file will be the fastest way to get there since only a single
programming operation is required.  This should be done by actually reading
the HEX file properly according to the spec, changing selected values, then
writing out a new HEX file with the custom values.  If you don't properly
read the HEX file, you'll probably have this problem again some time in the
future even if you manage to kludge around it now.

Reading a HEX file is easy.  Doing it right in the first place would
probably have taken less time that you already spent finding and thinking
about this issue 7 years later.  Don't make the same mistake again.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist