kicad-developers team mailing list archive

[Oliver Walters <oliver.henry.walters@xxxxxxxxx>]

I'd like some direction from a project leader on how I should progress,
rather than wasting my efforts:

1. Adding "DNP" option to schematic components.

This can be achieved now, without breaking the .sch file format. It allows
components to be marked as DNP in the schematic and in the exported netlist
and BoM files.

Should I submit a patch for this part of the feature? I can submit a
suggestion for a fully-fledged assembly variant management system after the
new sch file format is written. But I think this DNP feature is useful for
now. I know I would use it all the time.

2. Add "DNP" option to PCB

I think the schematic should be in charge of managing variants. The logical
information (supplier, resistor value, LED color) etc are contained in the
schematic and these values are what differ in assembly variation. So the
DNP status should be pushed to the PCB (so that footprints can be excluded
from assembly files as required).

a) I do not think that marking a footprint as DNP changes the placement
"type" (SMT / THT / virtual) it is instead a modifier

b) This requires a file format change. Would such a change be supported in
a 5.x release?

c) How should this information be encoded in the module description in the
.kicad_pcb file? Use the 'properties' token? Implement a new custom token?

Feedback appreciated. I'd like to move forward on this and am willing to do
the work to eventually support proper variant management. But need some
support from the higher-ups ;)

Cheers,

On Sun, Nov 25, 2018 at 3:38 PM Oliver Walters <
oliver.henry.walters@xxxxxxxxx> wrote:

> A feature I feel has been missing from KiCad is the ability to mark parts
> as "DNF" (Do Not Fit) so they are excluded from assembly files (BoM / PnP /
> etc).
>
> Many of the existing BoM tools (including mine) offer "hacks" to get
> around this shortfall by having a special field assigned to each component,
> for example.
>
> I have a branch working towards such functionality and am looking for some
> feedback.
>
> I consider this preliminary work towards full support of assembly
> variants. However this will need to wait until the new file format to be
> properly implemented. So for now, only DNF status is presented.
>
> Here are the features I have implemented so far:
>
> *A. Schematic components can be marked as "DNF" *
>
> A new checkbox in the component editor allows part fit to be deselected.
> By default all components are selected. (UI placement not final, just for
> demonstration).
>
> [image: image.png]
>
> Note that when rendered in the schematic, DNF parts are denoted by
> appended text after the RefDes field.
>
> Altium denotes DNF parts with a large red cross - I think that greying out
> DNF parts would look quite nice.
>
> *B. DNF part status is saved in the .sch schematic file*
>
> If a part is DNF , then the component line in the .sch file is appended:
>
> [image: image.png]
>
> Parts which *are* fitted do not get updated - to reduce file changes.
>
> As far as I can tell, this file change is fully backwards and forwards
> compatible. Old versions can open the file and simply ignore the DNF
> parameter. So perhaps this can be pushed into production before 6.x branch
> as it won't break any schematics.
>
> *C. Fitment status saved in exported netlist file*
>
> The fitment status of each component is saved to the exported netlist file.
>
> [image: image.png]
>
> So all this at least allows fit / DNF status to appear to the BOM tools.
>
> What's left?
>
> *1. PCBNEW*
>
> DNF status should be pushed to PCBEW, because:
>
>
>    - Don't show 3D models for parts which are marked as DNF
>    - Don't export DNF parts to the PnP files
>    - (Eventually) ability to switch between assembly variants in PCBNEW
>
> However, this would require a file format change to the .kicad_pcb file,
> and this does not have the same opportunity for version compatibility that
> the simpler .sch files do.
>
> I can make this happen, but I'm guessing it has to wait for the 6.x branch.
>
> A simple example of how this could be included in the file:
>
> [image: image.png]
>
> *2. Multi-Unit Parts*
>
> If you mark one unit of a multi-unit part as DNF then *all* other units
> should be marked as DNF too.
>
> Question: How (from SCH_EDIT_FRAME context) do I find all the components
> that are the same master component as a given sub-part?
>
> *3. Better Display of DNF parts*
>
> I'd like to add a "greyed out" display for DNF parts in the schematic
> viewer.
>
> *4. Nomenclature*
>
> In the files I have used "DNF" or "fitted" - what should the accepted
> nomenclature be here? I've seen DNF / DNP / NC and other examples used. I'd
> like to get some clarity on what I should use going forward.
>
> As I said above, I'd like to move this on to support a full assembly
> variant management system but I feel it's best to wait until new file
> formats. Until then, some feedback on the items above would be great.
>
> Thanks,
>
> Oliver
>
>