How to attach multiple circuits to same connector?

[kevinz]

I hereby certify that I am not simply asking someone else to design a footprint for me.

How can I connect multiple parts of a circuit to the same connector? I think an example or two would help me explain what I’m trying to do.

1. I have a resistor ladder of 8 push-buttons, wired off-board, on the front panel. Each button needs a connection to the resistor ladder, and a GND. I’d like to use a single 2x8 pin header connection to the push-buttons.

2. I’m trying to connect multiple strings of NeoPixels through a single connector. Each string has a +V and GND, and a digital input. Each digital input connects to a different GPIO pin on a microprocessor. Lets say I have four strings, and would like to use a single 3x4 pin header. Hope two images will help:
   
   

How can I indicate that the connection to each circuit is to just a part of a single connector?

Thanks for any advice. If my question isn’t clear, let me know and I’ll draw up the circuits.

-Kevin

[Piotr]

@kevinz

If my question isn’t clear,

I understand that you used at schematic and PCB 3 connectors having 8 pins each and you ask how to replace them wit 8 connectors having 3 pins each.

It is how I understand this:

@kevinz

connection to each circuit is to just a part of a single connector?

The answer is: start from using 3 pin connector symbols. Use 8 of them at schematic, make there wire connections and there should be no problem to map it at PCB.
If you ask how to clearly make these connections at schematic my recent post can be helpful:

First prototype PCB. Any tips or pointers? (arduino giga hat)

When connecting microcontroller to bus I place wires from each pin to bus then deciding what is connected where I just manipulate with labels. Unused pins are left with unconnected wires and I don’t remember ERC complaining on it. Ops… got an idea that I may be permanently switched off some warnings. Down to 0603 you can relatively easy hand solder having soldering iron with sharp tip. If it were my schematic the I2C connectors would look something like that: [I2C] And only one line (bus) …

[kevinz]

Hi, @Piotr, thanks for replying.

I’m not sure if what I’m asking is just a semantic difference, but it seems to me to be significant.

In this drawing that I just completed, I drew J8-14 as two-pin connectors.

However, I want them all to have a footprint as a 2x7 pin header. I understand that I can stack the 7 1x2 connectors together to form a 2x7 connector, and if you’re telling me that’s the right way to do it, I will.

I think that my question is similar to how to design with multiple logic gates, say, for instance 4 NAND gates in a single 14-pin DIP package, In this example, there’s four separate circuits but just one footprint.

Does this help? Thanks, again, for trying to help me.

-Kevin

[Piotr]

@kevinz

However, I want them all to have a footprint as a 2x7 pin header.
…
there’s four separate circuits but just one footprint.

Such gates have to have special symbol consisting of several parts. So you need special connector symbol consisting of several parts. I have never heard of such symbols.
I don’t use KiCad libraries. I use only my own libraries. So in such need I would just do the needed symbol.
But I don’t understand why you want it. If you want to use 2x7 pin header then why not use 2x7 pin header symbol. 4xNAND symbols are done as separate gates as to allow you to place them at schematic according to signal flow (so between NAND gates you can use other gates or flip-flops) to make schematic easier to understand. I have never heard of such need for connectors to be placed according to signal flow and then at PCB together.

[kevinz]

If you want to use 2x7 pin header then why not use 2x7 pin header symbol.

So, if I understand correctly, you’re suggesting I draw it like this:

Yeah, that works. I don’t know. I just like the symmetry and appearance of the separate connector symbols. I think it conveys something about the circuit, that the single connector confuses slightly. I don’t know. I’ll have to think about it some more. I just thought what I was asking for was common practice and that I just couldn’t find it in KiCAD.

Thanks again, @Piotr, for your help.

-Kevin

[Piotr]

@kevinz

So, if I understand correctly, you’re suggesting I draw it like this:

Yes. But from first post it looked that you rather need 3x8 and not 2x7. As 3x8 may not be among standard pin-headers than may be you needed rather a serie of 3 pin-headers.

[3Dogs]

If you really want to scatter connections around the schematic, you can “connect them by name.”
Just put the single 2x7 header symbol at the side of the schematic, and have connections with net names on each pin. Then, use those net names wherever you want in the rest of the schematic.

[jmk]

Why not something like this?

A single 9 pin connector. All the Gnds are connected at the switches.

[kevinz]

Thanks for responding, @jmk.

Why not something like this?

Well, to me, this seems to imply that the circuit board contains both pin and socket connectors and switches, when it really just contains the connectors.

-Kevin

[jmk]

I changed the drawing in my above post.

To make your schematic easy to understand, you need to include all the circuit.
If the schematic is large, you may wish to have different sheets (pages) for different sections. eg. Have the front panel symbols on a different sheet.
If the schematic is small, you may wish to have everything on the one sheet. The choice is entirely yours.

The example I drew now clarifies what is not on the PCB.
NOTE: P1 and switches 1 to 8 have had their Attributes in their Properties edited so they are now “Excluded from the board”. This means when you start the PCB using “Update PCB from Schematic”, P1 and the SWs. will not be present for your PCB.