Jan-Erik Soderholm wrote:
> Actualy, since we (currently) are planning to use Wouters
> "Dwarf-boards" as the PIC-platform, I think that I'll see if the code
> is easily ported to a 18F252. There doesn't seem to be any major
> problem with that judging from the shematics. I'll install a copy of
> HOS in the Embedinc/Olin environment and take a look at it.

I'll assume you meant HAL project, not HOS, since HOS is just a template and
doesn't do anything useful or cool by itself.

It will take some work but shouldn't be too bad.  It's been years since I've
been in that code, but some things I can think of off the top of my head:

1  -  The larger program memory space of the 18F252 will allow for longer
total stored sound or high sampling rate.  All in all you get about twice
the length*bandwidth of the 16F876.

2  -  Some of the code is specific to the 14 bit program memory word size of
the PIC 16, and it goes thru some trouble to treat a 14 bit word as two 7
bit samples.  This will have to be rewritten.  However, using 8 bit samples
in individually addressed locations of the 18F program memory will be
easier.

3  -  For quick porting, you can still use the 7 bit samples stored in 8 bit
bytes.  It won't be any worse than the existing version but that way you
won't have to create new sound files.

4  -  The CCP module setup will be a little different.

5  -  The usual gotchas of porting 16 code to an 18 apply.  I probably
didn't count on DECF and INCF not modifying the carry bit, for example, but
its probably looking over everything once to save chasing strange flaky
problems later.

6  -  I think the PIC 16 interrupt routine structure will work on the PIC
18, but I would replace that with the proper PIC 18 structure.  I would
start the interrupt module with the QQQ_INTR18.ASPIC template, then move
code from the old module into it as its it's converted.  The code in this
module will need the most rewrite anyway.


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