I’m laying out a small signal analog board and have to route ground returns separately back to a star ground. However, in layout its not letting me do this - it’s showing a net link to the closest ground point and if I try to route past with a separate track, its highlighted in green and wont let me do it. Is there a way to override this? I’ve gone into the interactive router settingas, but dont seem to be able to disable this. I want to avoid using flashpads.
Here is an image of one example
I do not want to connect the thin track to the thick track, but to select the top copper layer and through the component and connect it to the star ground about 1 " away.
The collision highlighted in green is telling you there is a collision with a different net.
The ratsnest indicate that the two tracks belong to the same net and they are not (yet) connected. It only shows the closest distance. They can be connected at any other place.
Thanks. But I am not able to connect to where I want to go, despite it being the same GND net. If I try to join to the closest point, its ok. If I try to go past it and connect to a GND point further away (closer to the star ground), it will not let me make the connection - the track and via come up green and I cannot connect.
The best solution is probably to use net ties. In the schematic, you place a net tie in between each GND symbol and each IC pin that has to connect to the star ground. And on the PCB, you put all these net ties very closely together around your star point. This makes your star gnd a separate net, and each and every GND net has to be routed separately to it’s own net tie.
If I ‘Allow DRC Violations’ in the interactive route settings dialog box and I try to route from the GND (0V) incoming tab connector to the star ground, it will not let me do that.
If I route from the star ground to the GND tab connector with DRC OFF it lets me do that OK
Then I turned DRC back on again. The track looks good with no errors flagged.
I dont know enough about KiCAD yet, but it might be its objecting to the tab connector which is seeing as an input (my guess) going to GND. The TAB connector is the 0V connection that goes back to the PSU. Anyway, I’ll do some more digging over the coming days and see what comes up.
Might be I have to rename the 0V connector as GND?
KiCad only does live DRC checks during routing. If you turn off the checks for this and route it anyway, then there will still be a DRC violation, but you only see it if you run PCB Editor / Inspect / Design Rule Checker / Run DRC.
Yes, probably. If you have one net with the name “GND” and another net with the name “0V” then the names are different, and thus they are different nets in KiCad. There is nothing special to the “GND” name. It is just a net name, and often it is used as some convenient reference sometimes.
They are not the same net. They have different names, and thus they are different nets.
It is possible to use multiple different labels on a net. So you can use both “0V” and “GND” on the same wire. KiCad does give a warning for this (Because it does not know whether it’s accidental or intentional), but those ERC warnings can be easily suppressed (or disabled completely if you don’t like them at all).
For me, that was already a reasonable assumption I made myself, but on a medium like a forum, where questions and answers take from a bunch of minutes to hours to go back and forth it’s better to unambiguous. Especially towards beginners who are more likely to make faulty assumptions without realizing it.
