My first schemas, defaults ERC

Morning alls
I have done my first schemas, and some errors after ERC.
1> I don’t understand, GND are connected, I have placed Power-flag. (orange color)
2> not power supply in LM358, but I don’t know doing this.
3> Pin not driven (red color)
If possible to help me . regards

Thank you

Warning: symbol ‘GND’ has been modified in library ‘power’
KiCad has some issues with GND (all power) symbols. You should not modify them (as a beginner), but just use them as is. To be sure you use unmodified library symbols for GND, first edit the properties of one of your GND symbols, then use: [ Update Symbol from Library and update all onboard GND symbols from their library defaults.

Error: Symbol U5 has input power pins in units [Unit C] that are not placed
U5, an LM358 has three Units. Two of the units are the opamps themselves, and the third (Unit C) are the power pins. Make sure you place all units on your schematic, connect the power wires (and properly passivate unused opamps). You can change the “Unit” in the properties panel of anyone of the symbols on your schematic.

Error: Input Power pin not driven not driven by any Output Power pins
The net on the +28V power symbol needs a: PWR_FLAG symbol (See below).


You very likely need these PWR_FLAG symbols on most of the power nets. I usually put these power flags near the connectors where power enters the PCB. They allow ERC to verify that you IC’s are getting powered from “somewhere”. Voltage regulators most often have one of their pins set to a power output, and then that net does not need the PWR_FLAG symbol. The use of these PWR_FLAG symbols often leads to some confusion for beginners, and how to use them as been mentioned a lot on this forum. See for example: ErrType(3): Pin connected to some others pins but no pin to drive it

I understand the OP’s questions here. I also run into the issue with “modified power symbols” every third update. Extremely annoying.
And that the LM2904 (base symbol for the LM358) doesn’t even have a proper “Unit C” symbol crowns it.
I love my personal libraries.

Hello, thanks you for return.
GND is OK, perfect.
Again error with power flag after adding , I don’t know why.
I have not understand to add power supply in LM358, must I do modify symbol lib ?? or generate new ?
I have an other problem with L1 L2 L3 > library not include PSPICE
thank you very much.

A LM358 symbol in the Kicad library has 3 parts… A, B & C. Part C is the power supply. See @paulvdh above, or the below screen grab.

The top line shows the three parts taken from the Kicad library. The bottom line shows how part C (the power supply can be added to part A. Part C may also be added to part B or left separate as in the top line.

Ha ok, sorry , it’s ok now.

I have again two errors…;-(

Have in mind that ERC is very simple test not understanding electronic.
You have somewhere two pins defined as power output and connected together. ERC don’t understand that power can sometimes come from two sources.
If you have power input pins connected to net and no power output pin is connected to that net ERC is also not happy.

Ok, manually I checked my schematics it is correct, so that means everything is ok for routing??

It depends how sure you are of your manual check.
I don’t have such doubts as I never run ERC :slight_smile:

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Not really, @frank63 just has added a PWR_FLAG to a pin which KiCad knows is already a power output. This is useless and makes KiCad think there are two power outputs (one from the pin, one from the PWR_FLAG). PWR_FLAG should only be used when KICAD doesn’t already see a power source, but you know that there is one. Either because the power flows through some passive component (fuse, filter, …) or because the power comes through an external connector.

I didn’t noticed all these PWR_FLAGs in the schematic corner so simply based on what error message says. Not distinguishing PWR_FLAG pin from other pins ERC misled me. May be if I’ll be using it myself I wouldn’t be fooled if I had more experience.

Hello alls,
I have done modified my schematic, and I have 3 x ERC errors, but I don’t understand why ? it is very simple here…see red arrow.
Thank you

I might help to switch the language to english for the screenshot, many people here probably don’t know French well enough.

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Also very difficult to see what is happening when the top of the schematic is cut off and half the bottom is covered with the error panel.

I am guessing it has to do with the missing PWR_FLAG symbols. I see three ERC error arrows on power inputs.

Sorry for language, see update.
I have only one power flag for GND, alls power supply are now uniques from 12V.
12V >>>>. regulator 6V
12V >>>> stepup 28V >>>> regulator 15V

Yep, I guessed right.
If you get any sort of error message (whether it’s in KiCad, GCC, another programming language or other software) the quickest way usually is to just paste the error message itself in a search engine. Just like:

Or directly on this forum, where it has also been answered 50+ times:

I will say once more:

When you satisfy it by adding some PWR_FLAGs that will not mean that your circuit is correct.

Why we don’t see U1 and U2 type at schematic?
Even don’t knowing what they are I can say - their application here looks amazing.
Are you sure that you want to load U1 with 6/180 = 33mA and U2 with 15/220 = 68mA?
If you are sure of your schematic then - ok. If no - discuss your circuit at some electronic forum.

The best answer :wink:

it’s stronger than me :slight_smile:

Next step >> routing

Not exactly :slight_smile:
In PCB design 90% of work is placement and it is your next task (if you are sure your schematic is correct - last we sow is not).

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