Re: [Kicad-developers] RFC: position file changes

[Cirilo Bernardo]

On Thu, Jun 16, 2016 at 10:22 PM, Wayne Stambaugh 
wrote:

> My preference is to define a reference position parameter for the
> footprint this way it could be any position the user chooses.  There may
> be reasons to use values other than pin 1 or the center of the
> footprint.  That one part that never seems to auto insert correctly
> comes to mind.  If you've done enough AI, you know what I'm talking
> about.  If the reference position is not defined, the center of the
> footprint is used.
>
>
I'll need some coaching on what various columns in centroid files mean.
In most centroid files I've seen there is only a "PosX, PosY" but some
have "RefX,RefY,CenterX,CenterY,PadX,PadY".

Now is it "RefX,RefY" which correspond to "PosX,PosY" or is it
"CenterX,CenterY"? Presumably the other coordinate specifies
the true centroid location as opposed to the footprint's nominal
location, but this still doesn't help us unambiguously determine
the Reference Pin Orientation.

Anyway, if I read you correctly, the "Reference Position" parameter
would require a change in the PCB file format since it would be
an offset relative to the footprint's nominal position. If we're going
to make a change to the PCB file format itself I think we'd need to
be very clear on what's written by the Position Export and how we
determine what columns will be written and how to respond to
missing data (Reference Pin).

- Cirilo


> On 6/16/2016 3:14 AM, Cirilo Bernardo wrote:
> > I will look into this; we can name any unreserved footprint property as
> > "RefPin" (do we translate it?) and if the pin exists then we can generate
> > the PinX PinY values in the centroid. The issue now is when do we output
> > PinX, PinY columns and how do we handle the case where a user may
> > have forgotten to explicitly define the RefPin on some parts?
> >
> > - Cirilo
> >
> >
> > On Thu, Jun 16, 2016 at 4:13 PM, Lorenzo Marcantonio
> > >
> wrote:
> >
> > On Wed, Jun 15, 2016 at 07:12:50PM +0300, Eldar Khayrullin wrote:
> > > It will be good if it will be selectable as option
> >
> > Not an option, make it explicitly *select* the pin 1 for
> orientation, it
> > will save troubles!
> >
> > Adding it to the footprint properties would be the easiest IMHO
> >
> > --
> > Lorenzo Marcantonio
> > CZ Srl - Parma
> >
> > ___
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> >
> >
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Re: [Kicad-developers] RFC: position file changes

[Wayne Stambaugh]

My preference is to define a reference position parameter for the
footprint this way it could be any position the user chooses.  There may
be reasons to use values other than pin 1 or the center of the
footprint.  That one part that never seems to auto insert correctly
comes to mind.  If you've done enough AI, you know what I'm talking
about.  If the reference position is not defined, the center of the
footprint is used.

On 6/16/2016 3:14 AM, Cirilo Bernardo wrote:
> I will look into this; we can name any unreserved footprint property as
> "RefPin" (do we translate it?) and if the pin exists then we can generate
> the PinX PinY values in the centroid. The issue now is when do we output
> PinX, PinY columns and how do we handle the case where a user may
> have forgotten to explicitly define the RefPin on some parts?
> 
> - Cirilo
> 
> 
> On Thu, Jun 16, 2016 at 4:13 PM, Lorenzo Marcantonio
> > wrote:
> 
> On Wed, Jun 15, 2016 at 07:12:50PM +0300, Eldar Khayrullin wrote:
> > It will be good if it will be selectable as option
> 
> Not an option, make it explicitly *select* the pin 1 for orientation, it
> will save troubles!
> 
> Adding it to the footprint properties would be the easiest IMHO
> 
> --
> Lorenzo Marcantonio
> CZ Srl - Parma
> 
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> 
> 
> 
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Re: [Kicad-developers] RFC: position file changes

[Cirilo Bernardo]

I will look into this; we can name any unreserved footprint property as
"RefPin" (do we translate it?) and if the pin exists then we can generate
the PinX PinY values in the centroid. The issue now is when do we output
PinX, PinY columns and how do we handle the case where a user may
have forgotten to explicitly define the RefPin on some parts?

- Cirilo


On Thu, Jun 16, 2016 at 4:13 PM, Lorenzo Marcantonio <
l.marcanto...@cz-dynamic.it> wrote:

> On Wed, Jun 15, 2016 at 07:12:50PM +0300, Eldar Khayrullin wrote:
> > It will be good if it will be selectable as option
>
> Not an option, make it explicitly *select* the pin 1 for orientation, it
> will save troubles!
>
> Adding it to the footprint properties would be the easiest IMHO
>
> --
> Lorenzo Marcantonio
> CZ Srl - Parma
>
> ___
> Mailing list: https://launchpad.net/~kicad-developers
> Post to : kicad-developers@lists.launchpad.net
> Unsubscribe : https://launchpad.net/~kicad-developers
> More help   : https://help.launchpad.net/ListHelp
>
>
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Re: [Kicad-developers] RFC: position file changes

[Lorenzo Marcantonio]

On Wed, Jun 15, 2016 at 07:12:50PM +0300, Eldar Khayrullin wrote:
> It will be good if it will be selectable as option

Not an option, make it explicitly *select* the pin 1 for orientation, it
will save troubles!

Adding it to the footprint properties would be the easiest IMHO

-- 
Lorenzo Marcantonio
CZ Srl - Parma


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Re: [Kicad-developers] RFC: position file changes

[Eldar Khayrullin]

It will be good if it will be selectable as option

В Среда, 15 июн. 2016 в 12:40 , Cirilo Bernardo 
 написал:

Hi Eldar,

 The problem I have is that different standards have different 
orientations. Even IPC now have "Orientation Level A", which is what 
is described in 7351B, and another one where Pin 1 is in what the EIA 
packaging standards call "Quadrant 3" (bottom left). The EIA 
specification in turn specifies a different orientation for Pin1 
depending on the SMT package. To make things worse, some 
manufacturers provide the same part in different orientations on 
tape. So while I can specify that the given orientations are 
according to IPC-7351B, to help users determine the orientation 
without ambiguity, it is good to have the Pin1 location in the 
position file as well.


- Cirilo


On Wed, Jun 15, 2016 at 2:21 AM, Eldar Khayrullin 
 wrote:

Look at IPC 7351 - 16 ZERO COMPONENT ORIENTATIONS and Figure 16-1.

В Вторник, 14 июн. 2016 в 6:53 , Cirilo Bernardo 
 написал:



Hi folks,

 Some assembly houses prefer to have a Pad1 location in addition
to the part centroid location; this makes the orientation of the
component unambiguous and can help in cases where the user's
footprint doesn't align with the tape orientation of a component.
Would this be a useful addition to the placement file or are there
any objections to it?

- Cirilo



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Re: [Kicad-developers] RFC: position file changes

[Cirilo Bernardo]

Hi Eldar,

 The problem I have is that different standards have different
orientations. Even IPC now have "Orientation Level A", which is what is
described in 7351B, and another one where Pin 1 is in what the EIA
packaging standards call "Quadrant 3" (bottom left). The EIA specification
in turn specifies a different orientation for Pin1 depending on the SMT
package. To make things worse, some manufacturers provide the same part in
different orientations on tape. So while I can specify that the given
orientations are according to IPC-7351B, to help users determine the
orientation without ambiguity, it is good to have the Pin1 location in the
position file as well.

- Cirilo


On Wed, Jun 15, 2016 at 2:21 AM, Eldar Khayrullin 
wrote:

> Look at IPC 7351 - 16 ZERO COMPONENT ORIENTATIONS and Figure 16-1.
>
> В Вторник, 14 июн. 2016 в 6:53 , Cirilo Bernardo <
> cirilo.berna...@gmail.com> написал:
>
> Hi folks,
>
>  Some assembly houses prefer to have a Pad1 location in addition
> to the part centroid location; this makes the orientation of the
> component unambiguous and can help in cases where the user's
> footprint doesn't align with the tape orientation of a component.
> Would this be a useful addition to the placement file or are there
> any objections to it?
>
> - Cirilo
>
>
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Re: [Kicad-developers] RFC: position file changes

[Eldar Khayrullin]

Look at IPC 7351 - 16 ZERO COMPONENT ORIENTATIONS and Figure 16-1.

В Вторник, 14 июн. 2016 в 6:53 , Cirilo Bernardo 
 написал:

Hi folks,

 Some assembly houses prefer to have a Pad1 location in addition
to the part centroid location; this makes the orientation of the
component unambiguous and can help in cases where the user's
footprint doesn't align with the tape orientation of a component.
Would this be a useful addition to the placement file or are there
any objections to it?

- Cirilo

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Re: [Kicad-developers] RFC: position file changes

[Lorenzo Marcantonio]

On Tue, Jun 14, 2016 at 01:53:09PM +1000, Cirilo Bernardo wrote:
> Hi folks,
> 
>  Some assembly houses prefer to have a Pad1 location in addition
> to the part centroid location; this makes the orientation of the
> component unambiguous and can help in cases where the user's
> footprint doesn't align with the tape orientation of a component.
> Would this be a useful addition to the placement file or are there
> any objections to it?

IIRC the 'pad 1' position was already requested in the past. Of course
*in addition* to the centroid.

The real issue is determining *which* is the pad 1! from 'easy' case
like alu capacitors (is 1 the positive?), diodes (but then there is no
single convention, 1 is A o K?) to some rather esoteric ones (partially
populated BGA, pin 1 is maybe A2). The correct way to handle this would
be to simply add an attribute to the pretty schema saying the identity
of pin 1...

-- 
Lorenzo Marcantonio
CZ Srl - Parma


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