why is KiCAD not following rules for nets. VDD turns into GND - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: November 13, 2023, 04:14:08 am
content: I have a schematic I made. I have nets. Like VDD, VSS and GND.On the schematic they look fine. On the PCB editor the nets are renamed. Like VDD does not wanna exist and I get caps with GND on both sides.How do I just make it plot what the hell is in the schematic without making decisions to change something based on something I can't find. I don't need that feature. I figure its some crap with the parts. I just want it to do what it says its doing.I don't want whatever its doing.I can just plot lines everywhere to make it a star ground on the schematic and then put a plane over it.. but WTF, I should be able to use nets. Why the fuck is it changing the god damn net. There is no problem.Oh, ok. I wrote this out and then I figured its trying to help me, cryptically. There was a short through a diode on the ass end corner of a schematic bridging things. I guess it would be nice if it told you plausible short circuit. Maybe it does in the ERC but I Have like 999 problems there. The sky is falling because of some floating N/C pin but the short circuit between VDD and GND is hidden on priority #485

author: Shonky
author_rank: Frequent Contributor
timestamp: November 13, 2023, 05:31:24 am
content: Yep I expected schematic to be wrong when I started reading.And it would have been a short that you created in your schematic. Who put it in the ass end corner of the schematic?If you have a heap of problems in DRC then there's your problem. You should have zero. Then it's simple to find real errors like you were having rather than the ones you just want to ignore.

author: coppercone2
author_rank: Super Contributor
timestamp: November 13, 2023, 05:50:47 am
content: maybe if I was being paid to make it at work I am not gonna go through all that BS, not for this prototype, I wanna get this done !!!i usually proofread it by looking at the print out traces with the data sheets and a marker

author: fourfathom
author_rank: Super Contributor
timestamp: November 13, 2023, 07:24:21 am
content: DRC won't catch this type of error, but if you did an ERC on the schematic it would have plainly told you "Warning: Both VDD and GND are attached to the same items; VDD will be used in the netlist"I don't always get to zero "errors", but I do check all the reports to see if they matter.

author: coppercone2
author_rank: Super Contributor
timestamp: November 13, 2023, 07:30:45 am
content: need assistant to read thisi decided to buy good interconnects and make a smaller pcb that i can hook into a different pCB later to test stuff because the mega boards are not worth it until you have zero uncertainty.i have more options for characterizing the board this way too, I Can know more about it, then making assumptions about the signalsalso I am going to put some AC tvs diodes into small pomona boxes that i can hook up to any bnc connector to protect the input like a connector saver so their universal for prototypes, easy to test the effect of, and not have to rework a pcb with expensive parts on it with solder

author: Kleinstein
author_rank: Super Contributor
timestamp: November 13, 2023, 09:12:43 am
content: There may be a possible direct like in the schematics, likely unintentional.A possibly trouble can be parts with hidden / implicite supply pins. This is common with the single gate logic chips. These parts imply the there supply is GND and VCC even if intended to be used differently.

author: JPortici
author_rank: Super Contributor
timestamp: November 13, 2023, 11:42:14 am
content: Quote from: coppercone2 on November 13, 2023, 04:14:08 amand maybe 998 of them are "pin X is unconnected", which you can exclude from DRC if you prefer

author: Uky
author_rank: Regular Contributor
timestamp: November 13, 2023, 02:15:59 pm
content: ..Perhaps... KiCAD development team could consider adding the possibility of placing a "Dangle"-marker on intentionally unconnected pins. Thus, excluding this check can be avoided.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: November 13, 2023, 02:18:40 pm
content: i think i remember seeing the discussion that KICAD no longer uses netlist?i was not following that progression closely, maybe someone else heard about it and knows more ?https://forum.kicad.info/t/kicad-7-netlist-doesnt-work-as-supposed-to/41206

author: JPortici
author_rank: Super Contributor
timestamp: November 13, 2023, 05:04:31 pm
content: Quote from: Uky on November 13, 2023, 02:15:59 pmthere is already (the "x" symbol that marks the pin as "unconnected")

author: Benta
author_rank: Super Contributor
timestamp: November 13, 2023, 08:58:09 pm
content: Instead of whining, why don't you post the project (or at least the schematic)?Your descriptions are not useful, as you don't quite seem to know what you are doing.

author: coppercone2
author_rank: Super Contributor
timestamp: November 13, 2023, 10:02:46 pm
content: pcb does not exist anymore, the socket I got is chirstmas tree, so its gonna be point to point with some braid. two tiny boards. better anyway since I can test some very different packages there

author: janoc
author_rank: Super Contributor
timestamp: November 13, 2023, 10:22:36 pm
content: Quote from: 3roomlab on November 13, 2023, 02:18:40 pmIt still does, of course. Just you don't need to create it explicitly as a file anymore as it was in the old KiCAD, the netlist gets transferred between the programs in memory.That dude in the post is doing who knows what given the mismatched symbols and what not he had there, not following the correct workflow - then no wonder that things break for him. Garbage in, garbage out. There was nothing wrong with KiCAD there.

author: janoc
author_rank: Super Contributor
timestamp: November 13, 2023, 10:23:41 pm
content: Quote from: JPortici on November 13, 2023, 05:04:31 pmYep, just press "Q" on the pin to mark it as unconnected (or use the menu/toolbar). That feature exists since ages ago.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 14, 2023, 05:01:49 am
content: Quote from: coppercone2 on November 13, 2023, 05:50:47 amKiCad used to be quite simple minded and easy to use, but over the last few years ever more "advanced" features have been added, and more are comming. (There are over 500 feature requests on gitlab).And most features are not very difficult to learn, I find KiCad quite straightforward, but I've been using it for 8+ years (although i have not made very many PCB's with it) and my knowledge of KiCad grew gradually with the program itself.And both ERC and DRC are there to help you. KiCad V7 has gotten a lot more checks, and not all checks are useful for everybody. It is however easy to exclude individual warnings/errors, or whole classes of warnings/errors by right clicking on them in the ERC or DRC dialogs. (The excluded violations can also be easily undone)Quote from: coppercone2 on November 13, 2023, 05:50:47 amMistakes like shorting a diode though it's body with a wire are easy to make and hard to spot. A good tool for checking netlist connectivity in the schematic is to use the highlight function, which is (by default) under the backtick key (upper left corner of the keyboard on US layout, just under .)Rushing a project though KiCad without spending some time on learning KiCad itself does not sound like a good idea to me. There are so many nice things in KiCad that spending some time to learn them (such as for example the "No Connect Flags" already mentioned) helps boosting your productivity to get things done more effectively.

author: coppercone2
author_rank: Super Contributor
timestamp: November 14, 2023, 05:06:21 am
content: this board was unusually changed alot because I used it kind of like a virtual white board so alot of parts and sections were moved around for 40+ hours and parts added/replaced, something to hit by a stray 'group move' and embedded a strand of wire.IMO its as good as altiums junior program (circuit studio), which was wayyyyy better then eagle cad (ptsd flashbacks occur with eaglecad). Nothing like someone telling you not to worry about the phantom grid artifact that won't go away because their scared the license won't transfer over. And I swear that eagle changed via layer connections on me before. Ahh so you are paying me ignore the translucent criss cross artifact on my screen that looks like you went out of bounds in ghost mode on a video game.first time i saw circuit studio I thought wow you can take some guys off the blood pressure meds if you buy this. kicad is similarly good.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 14, 2023, 05:42:53 am
content: Just a tip, don't ignore ERC. Not generally a good idea. If you get a lot of warnings or errors, try to understand where they come from and fix that. (Often a single "fix" can solve a lot of warnings all at once.)

author: Benta
author_rank: Super Contributor
timestamp: November 14, 2023, 05:56:54 pm
content: Quote from: SiliconWizard on November 14, 2023, 05:42:53 amBest advice yet. Listen to it.

author: coppercone2
author_rank: Super Contributor
timestamp: November 14, 2023, 05:58:40 pm
content: Idk how you guys stand erc complaints if you did this for money before. I learned to hate cadIf I had some kinda machine to do it manually like a engraver shrink mill router thing I would use it based on hand drawings lol

author: Shonky
author_rank: Frequent Contributor
timestamp: November 14, 2023, 10:34:23 pm
content: And then you'll waste a lot of time trying work out why your boards don't work.ERC/DRC exists for a reason.

author: PlainName
author_rank: Super Contributor
timestamp: November 15, 2023, 07:50:51 pm
content: QuoteERC and DRC are like compiler warnings in software - the ideal is to get a clean build with no warnings. When I do this - for money or fun - that's exactly what I intend to end up with, because getting any at tells me there is a potential problem that will probably bite me at the worst time. And, of course, if you get a long list of warnings you mentally ignore, you'll probably never notice the extra one that's Bad News, so a clean slate is important just from that aspect.As with software, if you know what you're doing and why you're getting the various warnings, you might elect to disable specific ones, or specific instances. But the fewer such exclusions the better the quality of the job is likely to be.

author: coppercone2
author_rank: Super Contributor
timestamp: November 21, 2023, 07:08:19 am
content: when you run DRC in kicad

author: bpiphany
author_rank: Regular Contributor
timestamp: November 21, 2023, 10:05:10 am
content: Appropriate response?

author: JPortici
author_rank: Super Contributor
timestamp: November 21, 2023, 10:15:23 am
content: I could write a long list of complaints in kicad.the two things bugging me the most at the moment are-different default shortcuts for the same thing in eeschema and pcbnew-shortcuts i can't change or remove ("S" is giving me the most headaches)i agree that "nets that overlap each other for whatever reason get merged" is annoying but it's far from being a dealbreaker, that is an user error anyway, so it's far down in my list of complaints.one thing i'm not going to add to the complaint list is ERC/DRC being overzealous. I do this for money, i also do programming for money and first thing i do is enable every possible warning and setup static analysis. not using check tools because they give too many errors/warning is ridiculous. They can be bogus errors/warnings so you canexcludethose checks, but it must be a manual operation.

author: janoc
author_rank: Super Contributor
timestamp: November 21, 2023, 12:03:02 pm
content: Quote from: coppercone2 on November 21, 2023, 07:08:19 amMaybe that simply means you are doing something wrong that you have so many errors/warnings?In that case KiCAD is actually trying to save your bacon (and wallet) because if your order stuff with errors in it, it is likely to not work or not be manufacturable (or both).If you really think you know what you are doing (you aren't making a strong case for that here, though ...), you have always the option to turn both the individual diagnostics and also overall ERC/DRC checking off. It is right there in the menu. It is not like anyone is forcing you to use it.So I am not quite sure what are you whining about? That it can't read minds? When it doesn't warn you about your mistake (because you ignored/disabled the warnings), it is bad KiCAD's fault because it joined two netsyouhave managed to short together. And when it does warn you, it is bad KiCAD again because there are too many warnings that you couldn't be bothered to deal with in your messy schematic?Hard to satisfy this one ... Maybe you would do better hiring someone who actually knows how to use the software properly to do the job for you?

author: janoc
author_rank: Super Contributor
timestamp: November 21, 2023, 12:12:40 pm
content: Quote from: JPortici on November 21, 2023, 10:15:23 amI am pretty sure that is not the case in KiCAD - two overlapping wires don't get merged. The OP has most likely either put the connection dot between them or connected two wires to the same pin and then KiCAD assumes you do want to have these things connected and will put that dot there for you.Either way that's a user error that KiCAD has no way to know that it is not what you have intended.

author: JPortici
author_rank: Super Contributor
timestamp: November 21, 2023, 12:17:15 pm
content: Quote from: janoc on November 21, 2023, 12:12:40 pmthey don't get merged when you draw them, but when you move/rotate stuff and they happen to overlap. That is annoying but can worked around pretty easily

author: ebastler
author_rank: Super Contributor
timestamp: November 21, 2023, 04:55:29 pm
content: Quote from: janoc on November 21, 2023, 12:12:40 pmThe OP has long since figured out that he made a wrong connection in the schematic. It's actually right in the first post as a later edit:Quote from: coppercone2 on November 13, 2023, 04:14:08 amWhich then led into an extensive discussion of the fact that Kicad's ERC does indeed show many errors if the design has many errors, and whether or not that is a good thing...

author: Kleinstein
author_rank: Super Contributor
timestamp: November 21, 2023, 05:28:56 pm
content: If there is an unintentional conncetion in the schematics, the ERC may not even catch the problem. For the program it is hard to decide if the link is intended or a mistake. So it would not be about having to picky an ERC but possibly an ERC that could give even more warnings. There could still be a warning (e.g. like both ends of 2 pin part connected), but I don't know.When doing the layout one would normally notice such a fault at least. So some manual error check is still a good idea.

author: ebastler
author_rank: Super Contributor
timestamp: November 21, 2023, 06:09:31 pm
content: Quote from: Kleinstein on November 21, 2023, 05:28:56 pmWell, in the present case the ERC would certainly have detected the short between GND and VDD.And it detects clashing outputs as well. Actually, I don't think I have managed to sneak an unintended short past the ERC yet. But it is certainly possible, e.g. with bi-directional signals or parts where the pin properties are poorly defined.