Using two ground nets as one

Layout
1

Hello, I’m making my first KiCad project and learning a ton about circuit design.

I have my schematic pretty close to finished for a v1. I currently have a GND net and a GNDA net but after watching a couple videos of Rick Hartley it sounds like I should be using a single ground plane without a net tie and only separating the components.

I could change all my GNDA schematic symbols to GND but I would like to keep the names as is

  1. in case I later want to revert and have separate the nets
  2. to separate the analog and digital in my mind while I’m routing the PCB.

Is it possible and how can I tell KiCad to treat GND and GNDA more like the same net and keep the names?

2

You can make your own net tie footprint. Will the right custom net tie shape fix the problem?

I once made one on an inner layer. It involved some difficulty but I was able to do it.

3

A net can only have one name, and power nets take on the name of the power symbol.

If you connect GND and GNDAtogether in schematic, the net will, internally, become a single name (GND or GNDA), but the symbols will keep their labels.

This means that in Schematic, you can visually see which ground a component uses. However, in PCB, they will all have the same net name.

If you change your mind, break the connection in Schematic.

4

Does that produce ERC errors?

BTW when I designed a board with a net tie on an internal layer:

  1. I think I was probably using KiCad 6.X

  2. I think I cheated. I think I used a text editor to edit (probably the pcb file) because the net tie is a component of sorts, and KiCad does not like to put components on internal layers. (I cannot imagine why… :smiley:.)

5

I’m with BobZ. Use an inconspicuous net tie (but not a neck tie, that’s for management boards :wink:) and connect the ground planes to the nearest ground net.

6

Well, the default severity for two nets attached to the same item is a Warning.

Even if its default level was an error, no one will tell the ERC police if you exclude (or ignore) a message that you fully understand the cause of.

7

Thanks, Understood. But I do live in some fear of the ERC police. Around here, they wear hats which have a rotating microwave dish antenna.

8

You just need a rotating tinfoil hat. :rofl:

9

A net tie does not work in this case. It will preserve both nets (and their net names), but the nets will only be connected to each other at the location of the net tie.

To combine the two nets into a single big net, just connect the GND and the GNDA nets together in the schematic as baldengineer already suggested. You will loose one of the net names, because a net can only have one name, and ERC will generate a warning because KiCad does not know whether the nets are connected intentionally or accidentally, but you can easily suppress that warning by right clicking on it in the ERC dialog.