Confusing warning from Design Rules

I have completed a schematic. In it i have 8, i believe places where rather than tie grounds together manually i simply put a power port “GND”. They are all (i think) connected to something - a jack, a power supply ground, an input that ought not float, etc. One – only one - shows the error “Pin connected to other pins (true) but not driven by other pins (false)”. I sat false because 7 other things are called “GND”. Moreover, none of them have this error, so why is it being treated inconsistently.

I’m very confused. help :slight_smile:

Attached is the circuit snippet to see.

Pin connected but not driven

Everything ;labeled with GND ought to be connected to the screw terminal that goes to the product star ground.


a very confused guy

The GND symbol (like all power symbols) is created by use of a power input pin. ERC wants to have a power output pin on any net that has a power input as it otherwise assume that this net does not receive power. The solution is to tell ERC where you supply the power for this particular net. I assume your GND really comes from a connector which is most likely defined with passive pins.

You can either adapt the connector symbol (makes sense if you have a fully specified connector symbol for power supply inputs to help ensure all your systems use the same connection for power), or place the special symbol PWR_FLAG (that is simply a pin defined as power out with the symbol setup to not be exported to the board or BOM).

See ErrType(3): Pin connected to some others pins but no pin to drive it

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Your assumptions are correct.

I’l place the power flag.

What still confuses me is why, if that’s the case, i don’t have 7 more errors of the same type. 8 items on one net. How can one need a power drive and the others don’t? Weird. But thanks. Now i can sleep better :slight_smile:

The GND label is global and the DRC considers that your GNDs are all interconnected before it consider which one of them is actually the power source. Which label is identified as not being driven is (semi) random. You only need one source and PWR_FLAG per net. It would be pretty inconsistent to have to place a flag with every power source.

Each ERC error is reported only once. The ERC considers all your 8 errors the same error.

Thanks Pedro and John; clears up my mystery