A more common "migration" would be from the 16F74 or 16C74 to the 18F452
or 18C252. Microchip has an ap note on this migration. The 18 has several
more instructions that can simplify your code, but you don't have to use
them right away. The 16 and 18 behave a little differently on setting
flags or condition codes, especially on increments and decrements. Watch
for that. Also, the word size changes the way you do jump tables. You have
to shift left, then do a branch instruction. The goto is a 4 byte
instruction, so you'd have to do two shifts to use it. Also, bank
switching is considerably easier. There are more FSRs, and they are bigger
(high and low byte).

I'd have a look at the above mentioned ap note, change to the appropriate
Microchip include file, and test your code!

Harold


> Rafael Vidal Aroca wrote:
>>     Hi, i'm migrating a 16F628 based system to 18F452
>
> That's quite a jump.  18 pins to 40, 2K to 16K words program memory, 14
to 16 bit core.  That's practially a new design, not a "migration".
>
>>     2. May I use the code I have running in 16F628 in 18F452 with no
>> changes,
>
> Of course not.  The two processors have different instruction word sizes
for
> one thing.  If you wrote the original code with portability in mind, or
used
> something like my development environment (http://www.embedinc.com/pic)
then
> the source code only requires minimal changes and a rebuild.  If you
didn't,
> it's going to be more tedius.
>
>
> ***************************************************************** Embed
Inc, embedded system specialists in Littleton Massachusetts (978)
742-9014, http://www.embedinc.com
>
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