Trouble Tracing USB Signal with Defined Net Class in KiCad

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1

Hi everyone,

I’m having trouble tracing a USB signal. I defined a net class for it in the board setup, specifying a trace width of 1.1mm and a gap of 0.1mm between the differential pair. However, I couldn’t get the defined trace to appear. I’m not sure what I did wrong. Any advice would be greatly appreciated!

Thanks in advance

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2

I think the + in /D+ is interpreted as the Kleene plus for regular expressions so you have to escape it as /D\+

3

I have never played with DP, but do the DP Gap can be smaller than Clearance?

4

Netnames D+/D- should work (just tested, placed on rootsheet)
netclass gap < netclass clearance should also work.
but beware: it must have: netclass gap >= board constraint clearance

  • click (select a track segment of D+/D- and look at the bottom statusbar:
    • check the netname is it “/D+” and “/D-” ?
    • check resolved netclass → “DP” ??
  • id this is correct then at least the netclass assignment is correct.

Note that your second picture shows the “predefined sizes” dropdown in the Track&Via properties dialog. This dropdown is not populated with sizes from the netclasses, but from values defined in File–>Board setup–>DesignRules–>predefined sizes.

Please try to remove the old tracks and draw the differential pair again.