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EDA => KiCad => Topic started by: julian1 on October 05, 2016, 04:56:48 am

Title: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: julian1 on October 05, 2016, 04:56:48 am
In PCB layout, I try to set tracks and vias to their default net-class values, since that makes them super-easy to edit as a group.

But, occasionally for a single net-class, I want some of the tracks to be one width, and other parts of the track to be a different width. For example, a power-rail net-class, supplying small sot-23 transistors, but also supplying to-220 power transistors.

I've tried introducing 0R resistors in my schematics to force a net-class separation - but I'm wondering if there's a another way?.

Any ideas - short of making the track independent of the net-class defaults?

 
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: PCB.Wiz on October 06, 2016, 12:30:00 am
If you look at the Kicad database , what you are doing is probably the best.

If you want to flip between two rules, you can do that in the Design Rules area with two widths for example.
eg define rule-sets GND_N and GND_W, and remap GND net to each of those, as you need to route with differing default widths.
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: richardlawson1489 on December 30, 2016, 06:50:28 am
I agree. You are on the right way. I don’t see any other way. :)
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: technotronix on January 02, 2017, 12:16:46 pm
May you can find some more detailed information here. http://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html (http://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html)
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: julian1 on January 02, 2017, 07:57:21 pm
Different kind of subnet ;-). Also RIP is for joining layer2 subnets.
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: donotdespisethesnake on February 01, 2017, 05:53:05 pm
LOL, I think technotronix is some kind of spam-bot. I can't see who they are spamming for though...could be the long play.
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: julian1 on February 02, 2017, 04:47:27 am
I think it was a fair and funny poke at my incorrect use of "subnet" in the title. I should have said netlist which I think is the correct pcb design term.
Title: Re: Kicad - Is there an easy way to split a subnet without introducing a component?
Post by: donotdespisethesnake on February 02, 2017, 01:00:14 pm
I think it was a fair and funny poke at my incorrect use of "subnet" in the title. I should have said netlist which I think is the correct pcb design term.

I would say a "net", a "net list" is the list of all nets in a schematic.

I think the thing you are looking for is called a "net-tie", there is an example here http://electronics.stackexchange.com/questions/266902/kicad-connect-power-to-bidirectional-pin (http://electronics.stackexchange.com/questions/266902/kicad-connect-power-to-bidirectional-pin) You might need to amend the pads according to DRC rules.

I use the net-tie because it works better with an autorouter, but you can select a custom track width when routing a PCB by hand, which for one-off purposes might be easier.