Best practices: Pin-on-pin connection? Junctions dots?


#1

Hi! is a pin-to-pin connection without wire allowed in the schematics? My ERC/DRC (Kicad version 4) doesn’t complain, but a guy told me it’s not allowed, so I’m now unsure…

And one additional question, do I need a place junction if
I have two pins and one wire on one spot (as on the
image)?


#2

It may not be encouraged, but I think you are asking does it work ?
That’s something you can check for yourself.

Parts with no connection, have halo circles on their pins, and those go away when connected.
You can also check the netlist, to be 100% sure.


#3

Alright, then it’s perfectly fine as is, shown on the schematics screenshot, since no halo circles or anything appears.


#4

There are many things to be considered in making the schematic. The bottom line is how well it conveys the information you intend. In this case where you are sure nothing will be added it is pretty concise. If unsure I like to add a trace that is ‘three units’ long so if I do connect I can do that in the middle of the trace.


#5

We must have gone to different schools together.

Dale


#6

Working with schematics on a daily basis, none of the schematics that were provided contained the “Junction Dot”. It is not needed, and can actually cause problems with readability, especially on paper schematics that get handled a lot.

There is no reason to add the extra wire connections in the schematic if the symbols are created to be reasonably spaced.

Here is a screen of what to NEVER do, even if KiCad requires the “Junction Dots” for some connections at this point in time:

If KiCad developers were not swayed by an individual to FORCE “Junctions Dots” on every schematic junction, this is what it could look like:

Currently the KiCad ERC requires some connections to have “Junction Dots”. Some of the “Junction Dots” are just visual clutter, and some of them are actually needed to make the connection between nets.


#7

Everyone has different preferences for this in terms of readability. KiCad errors on the side of caution and will place a junction dot whenever there are more than two items at a position. Likewise, it will remove junction dots when there are only one or two items at a position.

In terms of netlist, KiCad will connect everything at a pin end, junction dot or no.

–edit– I see @sprig also answered this. They have good suggestions for standardizing your notation as well. Both options follow IPC convention (2612) as well as the older ANSI Y14.15.


#8

PLEASE program the option of “no junctions dots ever”!

I do not need “junction dots” in my schematics at all.

What I would like is to make the “non-connect” larger, bolder, and possibly highlighted after ERC.


#9

One reason to place a small wire in between is to get a place for using the highlight net tool. Right now it can only be activated on a wire. (Bug report regarding this: https://bugs.launchpad.net/kicad/+bug/1804944)

How do you then communicate (in a fool proof way) where connections are and where they are not?


#10

Never allow “junction dots” and “4-point connections” in the schematic that the technicians need to use.

ON EDIT: Sorry, but I can/will not upload examples.


#11

There was a discussion a while back and folks would at least like to see the connection dots as configurable. I’d like to make mine smaller than default in most cases.


#12

It seems the size should be configurable in the nightlies. The bug report is marked as “fix committed” https://bugs.launchpad.net/kicad/+bug/1545422


#13

Dimensions->Junction size

EDIT: changin the sizes of the already existing junctions require closing and reopening the file or some other trick, only new junctions get the size automatically.


#14

Can you add this as a wishlist item with some details of what you’d like to see to the bug tracker? That will help us to prioritize it and look to implement it in the future.


#15

Yes . . . many shops have “house rules” that prohibit this. The restriction is rooted in limitations of the “diazo” (and earlier “blueprint”) reproduction process. Designers who do that may be soundly berated by the old guy in Configuration Control. (You know, the one with sleeve garters and a green eyeshade. Or else his female counterpart, the frumpy sourpuss, will appear at your desk and rap your knuckles with a ruler.)

As best I recall, the KiCAD conventions regarding junction dots are compliant with every set of house rules I have ever encountered, and more conservative (less error prone) than many.

Dale


#16

If you configure them smaller than line width they disappear anyhow. :wink:

Still I think just large enough to barely notice is my aesthetic limit on these. Just a quick check that it is connected if in doubt. The current size DEMANDS attention.


#17

See above, if you make the dot = wire size, they visually vanish, and looks like that’s in there already.


#18

Granted if the connection dots are there but hidden by being the same size as the line width, then you will never see where you accidentally made a 4-way junction instead of two crossing nets. Configuring the junction dots off would also force disallowing 4-way junctions at the tool level (KiCad) instead of having it be a “house rule”.

Also, it isn’t quite “in there already”, as it is only in the nightlies. Not in the 5.0.1 official distribution. (I haven’t been checking the 5.0.2 development builds so I don’t know if it is there, or only in the nightlies targeting 5.1.0).


#19

Then somebody will complain they want no dots AND 4-ways. Enforcing another rule just enforces another problem to someone with an exception. Size configuration should be sufficient if you don’t want to see them. I don’t code much so I don’t know the implications of doing this in code though. With things like BGA’s becoming more common who knows what will happen in that maze?


#20

I knew someone would eventually see the KiCad “Junction Dots” as a problem for some industries. As I stated, I have not seen a schematic with junction dots since sometime around 1986 (well aside from some in really old manuals that were created well before then).

Only question then is, "Does this setting also affect the “Not Connected” indicator? Because it would be really nice to be able to make the “Not Connected” indication as obnoxious in size as the current “Junction Dots” are; and possibly change the color to something equally obnoxious.