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About Matched Lengths Between Pairs

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  • About Matched Lengths Between Pairs


    I have DisplayPort signals including 5 differential pairs: D0...D3, CLK.
    These pairs must have the same length.

    I created the class Display_Diff with these 5 pairs.
    I created a rule: MatchedLengths_BetweenPairs and applied it to Diff Pair Class > Display_Diff.
    I set up a tolerance of 2.54 mm ("Group Matched Lengths").

    The Differential Pairs Editor shows that the pairs do not match with the rule (big differences between lengths).
    I am a little bit troubled not having any warning.

    Thanks for help.

  • #2
    Any idea ?


    • #3
      What are the exact expressions? Maybe you may need to use different expressions? I have seen also your previous questions, that could be probably the same problem. Maybe this can help?


      • #4
        Here are both rules


        • #5
          Did you try press "Test Queries"? Does it select the diff pairs? Maybe try to use expressions as in the video I attached above.


          • #6
            Here are both screenshots after "Test Queries".
            Everything looks good.
            The BetweenPairs rule applies to DP pairs only.
            The InPairs rule applies to all pairs: DP and USB.

            I do not understand what the issue is.


            • #7
              Maybe a bug? Did you try the same in different altium version?

              This is a screenshot from my project:
              Click image for larger version

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              • #8

                Where should the rule violation pop up ? On PCB > Differential Pairs Editor ?


                • #9
                  Here attached a screenshot of the Differential Pairs Editor.

                  Attached Files


                  • #10
                    As you can see on the screenshot below, I've tuned the length matching between pairs and based on the longest one.
                    How is it possible to set the amplitude of the ripples ? I didn't succeed in having the box to do that.


                    • #11
                      just move your mouse further .... This is my older video, but it still works similar way:


                      • #12
                        The errors are always visible under the same name as they are setup in the rules:
                        Click image for larger version

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                        • #13
                          I am sorry but I cannot change the amplitude of the ripples.
                          I selected "Interactive Diff Pair Length Tuning",
                          I clicked on the LMB and dragged >>> I got the ripple with a green bar

                          And then ?
                          How can I change the amplitude ?


                          • #14
                            in the properties panel (when you are in the length tuning mode):
                            Click image for larger version

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                            • #15
                              As you can see, the box to make me able to modify the amplitude does not show up