You get any ERC error exactly once per net.
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Yes, but I got no 0 for the GND net. It is a different net (or at least it is supposed to be!) than the PGND net. They are connected by a 10 ohm resistor.
Yet, the errors are eliminated when I put a PWR_FLAG on a net segment that’s connected to a connector.
This suggests somewhere there is a short between PGND and GND?
Meant to say I got 0 error for the GND net, just the PGND.
Or you have anything on the GND net that supplies it with a power output pin. Or the error is shown on some other pin than the GND symbol.
I said that poorly…
When I add a PWR_FLAG to a net on GND, the errors on PGND disappear. I guess that’s because PGND is “driven” through the 10 ohm resistor.
But, I would expect all pins connected to the GND net would have the error when the PWR_FLAG isn’t on the net. But, just the PGND has it.
Yeah, I"m looking for that. But, if that was the case, I would not get the errors on the PGND when the PWR_FLAG is not there.
Use the highlight net tool to see if the two nets are connected.
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Yes, the highlight net tool says they are connected! But I sure can’t find the connection.
Still looking…
Did you make one of the power symbols yourself? Are you aware that they work by having an invisible power input pin whose pin name is responsible for defining the net name? Tutorial: How to make a symbol (KiCad v5.1.x) section “Creating a custom power port (power symbol or power label)”
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No, I did not make myself.
Yes, I’m aware of the invisible power pin input.
But, now that you mention it… I did import a schematic from Eagle. I thought I switched all the GND symbols to Kicad flavor, but maybe there’s an instance on one that’s identical looking that’s actually different. Checking that now.
Eagle import places global labels as it can not import power symbols so maybe there is one such label left (they are rather small so easy to miss)
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Ok, looking for that.
I do have the Eagle grounds, but they are power input. Probably best to just replace all the Eagle ground signals. I haven’t learned how to do the equivalent of Eagle’s “replace component”, so I’ll figure that out and replace them all.
You can use the “edit symbol library references” dialog that is found in the tool menu.
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Perfect! But, I can’t edit that, can I?
Edited it–looks exactly the same. But, that fixed it!
Not so fast–just fixed it because it disconnected the GND signal when I did that.
Still searching
So, the two GND symbols I’m using (from KiCad) are GND and GNDPWR. I’m assuming the corresponding global nets are GND, and GNDPWR. NOT net GND for both, right?
FINALLY FOUND IT!
Just like you said–a tiny GND label in a subsheet. Left over from before I decided to have a separate ground for power and small signals.
Thanks for the help! Glad I bothered to track it down–it was a real issue.
Hello!
If I may add my own explanation for something which I now think it’s obvious… but took me ages to understand… (not proud of it). I will add a recent example.
Basically Kicad expects your circuit to have some power at some point in the circuit. We can’t blame the software on that point.
Usually I design boards with an input power connector. As for the connector type on the schematic, it might be a row of pins, for instance 01x05 for the symbol. These generic symbols are usually “passive”, so when Kicad checks ERC, it finds out that the circuit has no power at all, although the connector used is actually a power connector. For example a circuit using a power connector like this will generate 5 errors, one per power net.
Now the only way to prevent to have errors is to tell Kicad, this is a power net. And if you add a power flag for each of the power lines, then you will have no more errors. I think it’s more logical to set this flag on the power connector itself, that’s why I group them all here.
What is difficult to understand at first, ist that although you have many similar nets, you will have an error on only one of them, and the position of this error is random. Probably the first in the parsing order of the ERC tool. You can see on the next image than the top +5V has no ERC issue while the bottom rght one has.
I’m aware that this is a little out of the original poster question, but I would be pleased if it can save some time to newcomers.
Pascal
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