kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Mon, Sep 08, 2014 at 10:27:45PM +0100, Brian Sidebotham wrote:
> Sorry, but I don't like this patch because I want control of where the
> reference text goes on both assembly and silk layers. It doesn't
> necessary want to go in the centre of an electrolytic cap for example.
> Only for the very basic components is the centre an okay choice.
> 
> I would rather just allow to have a reference object on the assembly
> layer as well as the silk layer.

I implemented the IPC rule which tell that's the reference on assembly
goes to the insertion point (for pick and place cross-check). I think
it's OK if someone doesn't like it :D In fact it's silly for THT
component were the insertion point often is on pin 1.

However at the moment the reference simply *doesn't* appear on assembly
so it doesn't actually breaks the plot IMHO; at least at the moment is
useful.

I agree with you that a separate designator would be useful. The whole
story is here
http://blogs.mentor.com/tom-hausherr/blog/tag/reference-designator/
In short, silk refdes must be always outside the part, assembly refdes
needs to be always inside the part; quite a conflicting requirement...
since on silk you need to always hand place it (if it fits on the board,
i.e. never in my case:D) and many CAD have no separate assembly origin
it get placed on the insertion point (if you can't move it as you
reasonably asked).

The big problem is that reference and value are two slots in the module
class, not entities in the module and are treated in a special way (in
eeschema instead they are simply the 'first' in the attribute list). And
that text (other than in the file format) isn't really handled in layers
other than silk (could work but probably something would glitch). In
fact, if you noticed it, they are not even controlled by layer but from
the 'visibles' palette (and have their own colors).

How to handle that? The obvious thing would to have a separate AssemblyRef
member. And duplicate the whole shebang for handling the current
reference field *all over* pcbnew, adding a keyword in the file format
and so on. Well, it smells to me:P what if you also want value on
assembly? :D

Also how to handle it in the UI? do we allocate another visible index?
Even the picking code would need to be duplicated...

Suggestion on how to handle it are well accepted. I was thinking maybe
in some kind of printf-like expansion in user text where you could place
%R or %V or something and put it on whatever layer you wanted to achieve
the effect. The %-thing would be easy, checking that text works on
different layers is not :D for assembly we could just put a rule that
use a default if no other text is specified on the layer...

So a first step (useful in any case) would be changing text-in-module entity
specifications from:

- Reference lives on SilkTop (and it's controlled by a own 'visible')
- Value lives on SilkTop (and it's controlled by it's own 'visible')
- User text lives on SilkTop (and it's controlled by the master 'show
  text' visible)

...to:

- Reference and Value *no change* (seems fine to me)
- User text on any layer allowed in the module (i.e. the usual
  restrictions which change from one day to another); I think it could
  be controlled by the same master visible but taking the layer color.

That would be useful for having comment text in the module (I've missed
the feature in the past, actually...). Probably the new module editor
can handle the layer change, I didn't check. Otherwise I think that
simply adding the usual layer chooser would do the trick.

In the meantime I have no problem in backing out (maybe partially, only
the 'pull to origin' piece) the patch. Maybe Yet Another Option on the
plot dialog for enabling the movement? An assembly plot with the refdes
placed like on silk would be better than without refdes at all.

Tell me how do you like it

-- 
Lorenzo Marcantonio
Logos Srl