kicad-developers team mailing list archive

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

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