Managing off board components in KiCad


#1

If you have a design that has off board components, ( switches that are panel mount connected by a wire harness for instance) what footprint do you assign to that switch, or do you just leave it blank and ignore the error?


#2

I’m breaking protocol by posting before introducing myself, and I apologize for that. I’ll get around to it eventually…

I’ve often run into your situation, whether it’s a daughterboard, an off-board component, or non-schematic items that I want on the BOM. The answer to the first two is that the component connects to your board somehow, right? However it connects is the footprint. If it’s two wires from a switch, then make a footprint consisting of the two pads those wires land on. For non-schematic things like an external PSU, I create a symbol consisting of a rectangle without pins and stick it in a corner of the schematic somewhere, with its properties set appropriately.

Julia


#3

Hi Julia,

After the Amp Hour interview, no introduction needed :-). And thanks for taking the time to respond. Do people manage cable harnessing in KiCad? Or is there a better way to do it?


Guy


#4

Try this: https://forum.kicad.info/t/components-off-pcb/14707

I’ve not tried to see if the component shows up in the BOM or other effects. The thread then wanders off topic.


#5

This may be unpopular, but I’m of the opinion that those off-board parts don’t belong on the schematic at all. The reason is complicated, but the simplified reason is the schematic drawing isn’t the “proper” place to collect parts for your BOM - that would be on the assembly drawing.

Having said that, I agree, for a single board prototype with no significant off-board stuff, shoe-horning those parts on the schematic makes sense. I would do that too if necessary. Just be aware that’s not “how it’s done” in the industry (I’m open to correction, since it’s been some years since I’ve made a large technical data package).

I wish I lived near Chicago and Chris’ KiCon, because I’d really like to make a detailed presentation and/course on engineering drawing practices some day.


#6

There’s “the right way” as rclott hinted. At the systems level, the panel-mount switch + cable assembly may stand on its own at an equal level on the assembly hierarchy as the PCBA. Or, it could be that the switch is mounted to the panel as part of the panel subassemby, and the PCBA is is joined to the panel (with the switch mounted)… (Or the switch/cable assembly is attached to the PCBA first, tested, and then later the whole setup is mounted to the enclosure…)

As a practical matter, since I do most of my design in ECAD (I use Altium myself, but it doesn’t matter), I usually just use a separate schematic sheet to capture the “miscellaneous” items. It might have to sit in its own project (depends on your software’s ability to cleanly exclude the items from being part of the netlist on the PCB), but it’s easier for me to just stay in my ECAD software than to have to separately manage the non-electronic stuff in a different environment.

It also has to do with how the different parts are managed – if you’re a bigger established company with supply management solutions, you have to be more formal about splitting your design along separately orderable pieces. For a solo or smaller shop, that’s just excess work…