Vicent Colomar Prats wrote:
> Olin, do you really ask me that? I do not think so. I think you are
> experienced engineer so why to make a question you know the answer,
> just to create more confussion? I think this only ads more offtopic
> to this post.

I was trying to ask questions that would provoke a little thought on your
end and reveal to yourself the silliness of your statements.  Apparently
that didn't work, so I guess I have to go thru this in little baby steps.
Your statement was:

> But I maintain that I prefer to protec
> unused pins thru limiting resistors against leaving them unconnected
> or tied to Vcc/Gnd.

So I asked:

> What are the resistors supposed
> to limit, considering these are unconnected pins in the first place?

Remember that we were talking about unused pins.  The discussion is in part
about what, if anything, they should be connected to since the circuit does
not have them connected to anything.  If they are left unconnected then
current can't flow to them.  Can't you see that limiting current in this
context makes no sense?  There already is no current to limit.  And that is
assuming you meant current should be limited and not some other value.  Note
that your statement never specified what these resistors are supposed to
limit.  Normally one would assume current from context, but since that makes
no sense in this situation it makes your statement ambiguous.

Then I said:

> And it's not clear what is supposed to be on the other end of those
> resistors from the PIC pin.

This was more to point out how poorly written your statement was.  The best
result would have been that you would have been embarassed that you made
such a ambiguous statement and that someone pointed it out in front of 2000
people, and you'd hopefully be more careful in composing future statements.
Trying to defend it only makes you look worse.

Explanation: Look at a resistor carefully and you will see it has two leads,
not just one.  That means when you describe how a resistor is connected, you
have to specify what both ends are connected to.  Your statement only
specified one end be connected to the PIC pin.  Not describing what the
other end is supposed to be connected to is poor communication and bad
engineering.

I and others here keep beating on this, but unfortunately it still refuses
to sink in too often.  Engineering is about intelligent tradeoffs and
requires attention to detail.  This includes not only the design itself, but
the documentation and any other descriptions of that design, such as
discussions about it here.  A engineer that designs something but doesn't
document or communicate that design is no engineer at all.  As Dave Tweed
pointed out recently, you can view the end result of engineering as a pile
of documentation.  That's really all the schematic, bill of materials,
assembly drawings, parts locator, special build instructions, theory of
operation, test procedure, etc, are.  These need to be taken just as
seriously as producing the design in the first place, since without them the
design has no value.

And all this documentation needs to be clear and precise.  There is no place
for sloppiness.  This is especially true the wider and more diverse the
audience is, since there will be less common knowledge and communication
conventions you can assume.  The PIClist is such a place.  Inexact and
sloppy descriptions are especially bad engineering here.  There are also a
significant numbers of newbies here that might not be able to tell bad
engineering from good.  So yes, I and some others are going to continue to
hammer on sloppiness presented here.  Get used to it, or better yet, be more
careful so that there is no need for such comments.


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