[(mostly)SOLVED] No idea how to resolve 'attached to the same items

[olliver]

Hey all,

I’ve been busy working on a little project, and have removed all but one ERC error, that I cannot figure out.

Looking at other forum posts, I see they actually have visually multiple nets attached, but I do not and know not of which ones.

In the screenshot you’ll see an LMH-7322, which has two power pins, called VCCO. This shouldn’t be a NET, just the name of the pin. Its on PIN1 and 18 (top of my head, pin 18 is an invisible pin on the same location, cause we don’t have symbol pin mappings yet :p)

Also, I have a power plane for +2v5. All chips (4 in total, or rather, 2 chips, with 2 units each) have a few of these +2v5 (and also -2v5) rails.

Nothing is giving an error, except this VCCO and +2v5 thing. Looking at the schematic file with a text editor, I don’t spot anything obvious either, just the pin names.

I’ve tried to add a net-tie, just to see if it would matter, but alas. Interestingly, when I was looking at the same file on my laptop yesterday, it was puking on U2B, but on my Desktop right now, it’s U2A. But still only 1 error shows.

Since I’m a new forum member, I can’t post the schematic yet, https://gitlab.com/olliver/lapod/-/raw/add/lapod_logic_analyzer_breakout_and_pods/pod_lmh7322/pod_lmh7322.kicad_sch?ref_type=heads&inline=false but note that this is my WIP stuff, so will get force-pushed a lot and eventually removed from that location

P.S. be gentle, I am not an EE, far from it even

[Piotr]

I opened it with KiCad 7.0.10 (schematic standalone) and ERC shows me 0 Errors and 138 Warnings.

I have a warning saying that +2V5 is connected with VCCO (both are Hidden pins) and +2V5 will be used as net name.
I think the reason is hidden pin of IC. You should not use it. Hidden power pins are used by KiCad to set a net name. And here KiCad has two names to chose and don’t knows how user thinks of thet net. So a warning to inform that net is named may be not like you think of it.

I never use ERC so have no experience in understanding it.

[olliver]

Ouch could it be that you are missign the ‘.pro’ where some things are excluded? I also use 7.0.10.

Here’s my settings:

though turning those ignores to warnings, I still only have 32 violations in total. I’ll open it in eeschma and check. Nope, only 1 error (and the 3 text field that are to be ignored).

What erros do you get? Can you ‘save’ the erc output and share it?

As for the hidden pins, I thought that was ‘the kicad way’ to have multiple power pins, without having to connect them. By making it hidden, you don’t get the uglyness of garbled text.

BUT! Changing the visibility fixed the issue. So thanks for that; sad that this makes it very ugly It’s still confusing though, because the two pins are identical (except the number of course), both are VCCO etc.

[Piotr]

@olliver

you are missign the ‘.pro’ where some things are excluded?

I know that many things depend on settings. I don’t care these settings as I don’t use ERC.
Most Warnings I have are “The current configuration does not include the library ‘Device’.” and it is true, as I use only my own libraries so no KiCad libraries have in the library list.

Using hidden power pins was common in 80s with TTL ICs. When all symbols had power named as VCC and you have your power symbols as VCC than probably KiCad would have no problem with it.
But now as we are using so many supply voltages and several ICs can have VCC (the same name) that need be connected to different voltages using hidden pins for that has no sense. Last time I used hidden pins in IC was probably around 1990. You should not use symbols with hidden pins. Point!

[Piotr]

@olliver

What erros do you get? Can you ‘save’ the erc output and share it?

There is no sense in it, and, as I have KiCad at PC not connected to net, each file I have to copy between PCs. In past I had the second KiCad installation (with default settings) at PC I am writing but it is Win7 so not for KiCad V6+.

@olliver

sad that this makes it very ugly

KiCad way is to have separate symbol for supply. So 2 OpAms IC has 3 symbols (Amp+Amp+Supply) and you can locate all supply symbols in schematic corner.

[olliver]

You should not use symbols with hidden pins. Point!

Point taken! but then it would be nice if KiCad could make the distinction ‘visibly’ hidden, just for aesthetic reasons, or hidden like it is right now, which does have consequence.

Could be as simple as just allowing the pin number to be hidden (as those numbers overlap making things ugly.

There is no sense in it, and, as I have KiCad at PC not connected to net, each file I have to copy between PCs.

Ah, no worries, don’t need to trouble you; and if it’s mostly warnings about the library, understood. That’s fair.

KiCad way is to have separate symbol for supply.

Sure, but I thought the ‘standard opamp triangle’ has those as part of their symbol. Heck I took the design of the symbol from the TI datasheet, where they model it the same way. I thought that was conventional wisdom.

[Piotr]

@olliver

I thought that was conventional wisdom.

I use 0 OpAms and logic gates only occasionally (single gate ICs) so I use symbols with power pins directly at them. There is so little of them so no problem with it. Also I prefer to see how each IC is powered in the place where I see signals in it. I don’t connect any IC directly to VCC net, but always through ferryte bead and C.

@olliver

Could be as simple as just allowing the pin number to be hidden

In all symbols where pin function comes from symbol (like transistor) I have pin numbers switched off.