Connecting nets without wires on schematic - Page 1
Forum section: electronics / general

author: John Coloccia
author_rank: Super Contributor
timestamp: November 19, 2016, 09:44:34 pm
content: In Diptrace, I've gotten used to the idea of "net ports". They're one pin components you can make, and the idea is that you drop it on your schematic in a convenient place like any other component (a resistor for example, or even better a ground symbol), and attach nets to it. So for example, I can make a net port named "VCC", and whenever I need to attach something to VCC I can simply drop the net port there, hook it up and voila. Really neatens up a schematic. I guess it's essentially just naming the net, and identically named nets get attached to each other, but it does it visually and without risk of typo.LTSpice has a similar thing. I think they have a component called a net label, or something like that, that essentially functions exactly like the Diptrace Net Port.Is there any equivalent way of doing this in KiCad?Thanks!

author: PCB.Wiz
author_rank: Super Contributor
timestamp: November 20, 2016, 02:05:56 am
content: Quote from: John Coloccia on November 19, 2016, 09:44:34 pmIf you run your mouse down the right side menu, and read the hover-hints, you'll see there are a couple of choicesPlace Net Name- names any net and like-names join. There is a clear dot on the text, and that dot does need to contact a valid trace to connect.orPlace Global Label- similar action, but includes an outline symbol for the text, and colours differently.Works the same way, needs to have the connect-dot on a valid trace, and that names the NET.

author: John Coloccia
author_rank: Super Contributor
timestamp: November 20, 2016, 04:18:13 am
content: Quote from: PCB.Wiz on November 20, 2016, 02:05:56 amThanks! It's not too far off what I'm looking for. I was hoping there was a component that I could create so that I wouldn't risk a typo. I'll play around with this some, though. Might be close enough.

author: salbayeng
author_rank: Frequent Contributor
timestamp: November 20, 2016, 04:32:25 am
content: I haven't used kicad.But most schematic editors have a power supply symbol, you can double click/edit properties and change the shape of the symbol and the net name it is attached to.(I'm using Protel 99, and you can have "net labels" or "power supplies" or "ports" that are kind of similar functionality,you need to exercise caution to be aware if the labels are local or global or used with symbols, and note that nets like Vcc and gnd may already be assigned on some components)You should always label the important nets anyway, as it makes the schematics easier to read, and easier to work with PCB layout.

author: julian1
author_rank: Frequent Contributor
timestamp: November 20, 2016, 06:31:37 am
content: QuoteWhen you have one named global label - just position the mouse over it and use 'c' as shortcut to create a copy and drag it to where you want.

author: John Coloccia
author_rank: Super Contributor
timestamp: November 20, 2016, 12:07:20 pm
content: Quote from: salbayeng on November 20, 2016, 04:32:25 amThis hidden pin thing really disgusts me about KiCad. You make some decision at the component level that drives how you should organize you nets at the schematic level, and do it in such a way that it's a ticking time bomb unless you go to every stinking component looking for these power pins?? I think there are a couple of programs that do that, but it seems to me like a profoundly bad idea.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: November 22, 2016, 01:57:07 am
content: Quote from: John Coloccia on November 20, 2016, 12:07:20 pmOther CAD pgms have hidden pins too, (some call them SIGPINs) but KiCad is actually smarter here, in that you can enable hidden pins on a symbol, and connect to them if you wish.Hidden pins made sense way-back-when, with a sea of TTL gates using a single 5V Vcc bus.

author: Monkeh
author_rank: Super Contributor
timestamp: November 22, 2016, 03:07:06 am
content: Quote from: PCB.Wiz on November 22, 2016, 01:57:07 amYou mean like say, Eagle, with power pins and optional symbols? Nothing out of the ordinary here, just normal functionality..

author: John Coloccia
author_rank: Super Contributor
timestamp: November 22, 2016, 04:14:02 am
content: Oh, don't get me wrong. I know it's not a KiCad "thing" and other programs do it. I just think it's scary. I'll bet there are a lot of people that have been bitten by it at some point.

author: Thor-Arne
author_rank: Unknown
timestamp: November 22, 2016, 06:53:11 am
content: Like PCB.Wiz said, it made sense before.Today it doesn't.It's quite common to have both 3.3V and 5V logic on the same board.This will of course create issues when both have a hidden power pin named VCC.Currently KiCad doesn't alert you about having multiple net names on the same net either,so it's all up to the one doing the layout to see these problems.My solution is to use my own library, where there is no hidden pins.There has been some talk about changing the way power pins is handled.

author: John Coloccia
author_rank: Super Contributor
timestamp: November 22, 2016, 09:35:39 am
content: Quote from: Thor-Arne on November 22, 2016, 06:53:11 amI do that in DipTrace now. Every component I use comes from my own libraries.

author: salbayeng
author_rank: Frequent Contributor
timestamp: November 22, 2016, 09:39:03 am
content: On an EDN article I made a similar comment on hidden power pins, and the OP responded that every engineer he knew had been bitten by this, and I thought it was just me.I made my own symbol that fixed the problem. I Think the particular part was a CD4086? XOr gate, and it was in a manufacturers library (NS or TI?) that probably dates back decades!

author: suicidaleggroll
author_rank: Super Contributor
timestamp: November 29, 2016, 11:39:23 pm
content: Quote from: John Coloccia on November 20, 2016, 04:18:13 amGo to add a component and pick the "power" library. Those should all function the way you're describing.

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2017, 03:37:07 am
content: The hidden pins are annoying as heck. I edit the module and make them visible whenever I come across it, then I don't have to deal with it again for that part. This is one reason I mostly create my own components rather than searching for existing libraries.