Re: gEDA-user: Has anyone used SSOP28.fp?

[Steven Michalske <smichalske@xxxxxxxxx>]

On Jun 7, 2007, at 10:33 AM, L.J.H. Timmerman wrote:

> Hi Dave and all,
>
> If I remember this correct (on top of my head) the Gerber exporter
> ignores 1 mil lines by:
> <code>
>   if (gc->width == 1)
>     return;
> </code>
>
> It might be possible to filter out 1 mil (or a smaller, specific  
> width)
> lines and arcs for paste layers by ignore everything wider than 1  
> mil in
> a similar way in the mentioned stencil-hid.
>
> <code>
>   if (gc->width > 1)
>     return;
> </code>
>
> Filtering could/should be done in in the stencil_draw_* () functions.
>
> The stencil_fill_* () functions should translate any outline  
> parameters
> to arcs and lines.
>
> In this way those lines and arcs could be in the footprint without
> breaking the new-lib footprint file format.

Shouldn't the file format be forward compatible with a warning?
if an unknown parameter is introduced in the file format,  pump out a  
warning and continue?

example

Pin(-388 0 110 30 140 48 "3" "3" 0x00000001)
ElementLine (-388 160 -388 140 10)
PadSolder( ********* )


WARNING PadSolder unknown PCB element.


this wont protect earlier releases of pcb,  but allows for expansion  
of definitions.

Steve



>
> If you need boilerplate code for exporting of DXF entities let me  
> now, I
> got a dxf lib for writing to files (not reading) from my DXF exporter
> hid.
>
> Just my EUR 0.02
>
> Kind regards,
>
> Bert Timmerman.
>
>
> On Thu, 2007-06-07 at 09:04 -0700, Dave N6NZ wrote:
>> L.J.H. Timmerman wrote:
>>> Hi Dave and all,
>>>
>>> On Wed, 2007-06-06 at 11:24 -0700, Dave N6NZ wrote:
>>>
>>>> a) pcb paste layer gerber is directly from the pad layer, and I  
>>>> think in
>>>> many cases that lays down too much solder.  I haven't experimented
>>>> enough to be able to say for sure.  I'd like to see some paste  
>>>> layer
>>>> control added to the footprint definition.
>>>>
>>> Since this is on a per thickness, per material basis for the stencil
>>> involved, I think this could be better handled in a specific  
>>> "stencil"
>>> exporter with a configurable positive(=larger) or negative(=smaller)
>>> offset value for the pad-outline.
>>
>> That would be cool.  But I also think you want to be able so specify
>> different shrinks on a per-footprint/pad basis.  For example, for  
>> those
>> packages with a big heat-sink pad, that pad may want a different  
>> shrink
>> from the rest of the pins on the package, and different from the
>> default.  So, I could see some kind of format like:
>>
>> default -10% # any footprint, any pad
>> sot223.2 -30% # sot223 footprint, pin #2 gets special treatment
>>
>> Maybe something like that should even go into the footprint  
>> definition?
>> (I'm thinking newlib here, I never use the M4 stuff.)
>>
>> But in the end, I think the pad size adjustment in pcb should  
>> apply to
>> what is written to the paste layer gerber.  Converting to pad outline
>> vectors is better done in the gerber previewer or some other gerber
>> reader, since that yields a more general tool suite.  Of course, I  
>> won't
>> complain if pcb directly puts out the file that I need :)
>>
>>>
>>>> b) My current method for prepping a file for the laser cutter is  
>>>> a bit
>>>> of a kludge.  Ideally, I'd like to see the gerber previewer have  
>>>> the
>>>> option of exporting .dxf of the pad outlines from the paste layer.
>>>>
>>> If the exporter can be made configurable for not doing fill  
>>> operations
>>> on a pads in a pads-only-mode, then it's also possible to do this  
>>> for a
>>> DXF exporter.
>>
>> Yes, the fill just gets in the way as far as my laser cutting s/w is
>> concerned.
>>
>> -dave
>
>
>
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