ERC Errors - don't understand why


As title I have errors stating unjoined pins I have deleted them recreated them Tried using junctions between pin and wires but nothing. Interestingly some pins of the IC to wire have connected - really confused


Add power flags to the GND and +5V nets.

Somewhere else in your circuit you need to connect SCL and SDA using global labels. Perhaps you did not place the MCU yet?

regarding error type 3, in this FAQ article there is a bit more detail about it: ErrType(3): Pin connected to some others pins but no pin to drive it


Thanks both for the reply - my apologies you having to answer this, know doubt for the umpteenth time, after reading the answer (Rene_Poschi)

Yes Bobc, there will be other things to connect to it, and I will probably spill over to a second schematic sheet.


Sorry me again - where are the ‘Power Flags’ located?

I have tried right clicking on the +5V Symbol then Properties>Edit Properties and Symbol Properties is shown.

The GUI is not intuitive in use! How would I know to place another flag after I’ve chosen a +5V component - doesn’t make sense.


Read the documentation ?

use the add power symbol dialog (The same you use to add the +5V symbol) and type pwr_flag into the search field.

Edit: added this also to the FAQ article as this info was clearly missing from it. Thanks for pointing that out.

Bobc I have read the link you gavr before diving in. I’ve just reread it and can’t seem to find anything specific.

Rene_Poschi Ah! so there’s two symbols for power??? Should I use the power flag symbol instead of all my +5v symbols?

Incidentally, I got rid of the error(s) by deleting the +5V and GND symbols redoing them and then Annotate.

Thank you both

This is explained in the FAQ article.

But here again as a TlDr:
Normal power symbols are invisible power input pins. This makes them global labels.

The power flag is of type power output. It is not a global label. (So two PWR_FLAG symbols are not connected to each other)

OK so this could be the problem then - I have imported two IC’s with exposed VCC and GND pins into KiCAD and I’m trying to connect them to +5V.

I’m getting really frustrated, what am I supposed to do? (Show hidden pins option is clear)

Other than the Global Variable errors which I don’t care about, I now only have two errors left One on +5V and one on GND.

How do you suggest I proceed


You proceed by reading both the documentation that @bobc posted a link to and the FAQ article @Rene_Poschl posted a link to.

At the IC use the +5V and GND power symbols to connect your IC to those two power nets. Near where you source (or generate) each of those nets (battery, connector, power regulator, etc) Attach a single PWR_FLAG symbol to each of the +5V and GND nets. This helps embed some documentation to remind you that the power and ground nets are sourced near the flag symbols.

(Note you may not need a PWR_FLAG symbol on the output of a power regulator as they are usually power-output type pins. But if you pass that output through any passive components like a fuse or a filter you would need both the +5V and a PWR_FLAG on the output of the passive component(s).)

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I feel you have just given me a virtual middle finger and told me where to go!

I tried using Kicad about two months ago and I struggled with the interface. I have since read a lot of documentation and checked out YouTube. Only when I felt reasonably comfortable have I tried to proceed. Clearly I either missed a bit or not fully understood it. So guess what I asked the forum for some pointers. I do not appreciate asinine or obtuse comments when I am trying to learn and asked for help.

Next time kindly be more sympathetic with your post as you do not know the background of users asking t for assistance.

SembazuruCDE Thank you, I will look into this

No, he gave you sensible advice which you are wise to follow. I already gave you the answer and you ignored it.

You know, that works both ways. If you are trying to get help, lose the attitude. And if people take the time to reply, have the respect to read their advice.

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No, it was the index finger pointing to the links above. :wink:

Had you read the FAQ article Rene posted you would not have asked that question as the FAQ states:

(The PWR_FLAG is found in the power library supplied with kicad. Use the “place power port” dialog and type PWR_FLAG into the search field. Place it like any other power symbol.)

Again, this is answered in both the documentation and the FAQ article.

Why do you expect someone to spend the effort to retype an explanation that has already been given in the links that you can’t be bothered to read?

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I mentioned in my response that i added this info because of his question :wink:

Sorry, I didn’t realize that was the bit you added. At the end of the FAQ it also states:

Enabling “this is a power symbol” will ensure that it is shown in the “add power port” dialog.

Which does indicate where you could expect to find the standard power_flag symbol.

You have to miss the getting started:
where at page 18 PWR_FLAG is described.

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