Kicad newbie: how to add a test point (easily)


#1

I tried to extend a trace and add a large sized via at the end, as a test point (for scope probes).

When I sent it to seeed, they promptly caught the issue that my via had “no solder mask opening”, which obviously would not be suited as my test point.

I read on this forum that there is “do not tent via” option when generating gerber file. But I only have one test point, the rest of the vias are just regular vias, and I like these be covered with solder mask.

The question is whether there is an easy way to insert test point/pad into a pcb layout.


#2

If you don’t want to add the test point in the schematic, a quick and dirty way is to draw a filled zone on the mask layer above the via. If you can live with a square hole, that is a very quick hack, if you want it round-ish, you need to approximate with a filled polygon.


#3

Coming from someone that has yet to use Kicad, why not use a standard thru hole pad? Does it need to be associated with a part on the schematic?

Rick


#4

Pcbnew doesn’t have special services to cater for test points but adding footprints that act as test points works just as well.

Pre-existing ones under the name “Measurement_Points” might be in your libraries. If not you’ll need to make a new footprint that is nothing but a single round smd pad (or however to your liking) and use that.

You don’t need to add these to your schematic. Just remember to give them a net name, otherwise the DRC won’t like you.


#5

And to further expand upon @Veyrdite’s point, you need to do this by right clicking and editing a particular pad, not the entire footprint. The pad dialog is where you can insert a(n existing) net name.


#6

This is the library I used for surface test points (for pogo test pins) If you plan on getting stencils made, make sure the test pads are not present in your solder paste layer. I forgot to check this and my stencils have cut outs on all the test points. I have to manually scrub the paste off.


#7

Thanks for the advise. Yes, without adding the net name, I wasn’t able to connect the trace to it. That’s a very valuable tip.


#8

I was able to add measurement_points to most, but not all of my IC pins. It appears to be because KiCAD does not like the a net to have multiple names (VIN, RUN, EN). The winning net appears to be EN. I’ve tried adding global label, labeling the wire, and on PcbNew, I’ve made sure that I’m putting the net on the pad. What’s the correct way to connect measurement points? Thanks!!


#9

What you are trying to do is physically impossible. If you have 3 signals joined together, they are electrically the same. Therefore, you cannot have separate measurement points.

Since they are electrically the same, KiCad picks one name at random, but does not flag an error. To avoid confusing yourself, use one net name throughout. In the above, you have 5 different labels on the same net, that is 4 too many :slight_smile:

The same applies to BOOT/LDOIN.

If you place a jumper for each signal, then you could isolate them for testing.


#10

Makes sense. Thanks for the quick and graceful response Bob!
In other circuits I’ve placed 0 ohm resistors as jumpers. Are there other (better) options?


#11

Depends on your usecase. See recent discussions


#12

Note that there are a few symbols Test_Point… in the libs (at least in v5-libs) and there is a rather large set of useful footprints in different shapes and types: https://github.com/KiCad/kicad-footprints/tree/master/TestPoint.pretty