14 Replies Latest reply on Dec 10, 2018 11:57 AM by Markus Olsson

    route lengthening

    Graeme Parker


      As a new user to SW PCB I'm still getting used to where the tools are hidden.

      How do I interactively lengthen a route using a trombone shape trace?


        • Re: route lengthening
          Injy Gadalla

          Hello Graeme,

          Launch the Interactive Route command from Route. The cursor will change to Cross hair, click to start the route from the pad and press the Shift+A.

          Adding accordions,provides a dynamic means of optimizing and controlling net length by allowing variable amplitude wave patterns to be inserted according to the available space, and obstacles in your design. Press the Tab key to access the properties dialog while Adding accordions.

          The length tuning offers 3 approaches for specifying the target length. The length can be:

          • Manually defined
          • Based on a net that has already been routed
          • Defined by design rules

          To choose which of these methods is being used, press Tab during length tuning to open the Interactive Tuning Length dialog. The bottom of the dialog includes options that define the shape and dimensions of the tuning pattern, these can be controlled using the shortcuts detailed below. Options for selecting from the three Target Length modes are at the top of the dialog.

          Manual: The manual mode is exactly that, you enter the length in the Target Length field. The list on the right keeps track of the values you have typed in, in case you want to use one again.

          From Net: After selecting From Net you can choose a net from the list on the right. The length of this net will become the target, but it will be overridden if there are more restrictive design rules defined - we'll look more closely at the rules in a minute.

          From Rules: You need to have one or both of the Length and Matched Length design rules defined to use this mode.SW PCB will then obey the most stringent combination of these rules.

          There are 2 key ingredients to mastering the length tuning tool: knowing the shortcuts, and understanding the Net Length Indicator display. Let's start with the shortcuts available during length tuning:





          , (comma)

          Decrease tuning amplitude

          . (fullstop

          Increase tuning amplitude


          Decrease tuning pitch


          Increase tuning pitch


          Decrease corner miter


          Increase corner miter


          Toggle starting direction


          Open the Interactive Length Tuning dialog


          Whenever you are adding tuning segments with the length tuning tool, the Net Length Indicator displays. Use the Shift+G the Net Length Indicator provides a visual gauge of how closely the current route length matches the required length.
          The indicator consists of a white box, 2 vertical yellow bars, and a vertical green bar. Within the white box a colored slider will appear, indicating the current length of the net, with the exact length displayed in text on top of the slider.

          Hope this helps!


            • Re: route lengthening
              Graeme Parker

              That's great, thanks. I've nearly got the hang of it.

              When my accordion/trombone has been placed, can I re-position it or adjust its size?

                • Re: route lengthening
                  Injy Gadalla

                  Hello Graeme,

                  Yes you can, it is just a trace and you can double click on it to access its properties dialog.


                    • Re: route lengthening
                      Graeme Parker

                      Thanks Injy.

                      The problem is, when I place the accordion and try to move it as a whole, some of the vertices stay put and thus the accordion deforms.

                      If I double click to get properties, all I get is the property of one of the track segments that are part of the accordion. I don't see how, after this item has been placed, I can adjust its size (as a whole entity, not a single track).

                      Is there a video that you know of that shows this in practice?

                      I'm from a Zuken Cadstar background (a small player in PCB CAD) and track lengthening is very different. Here, you select an existing track and add the accordion. The accordion has resize boxes and is treated as a single entity unless you want to decompose it into individual traces. The amplitude, spacing and shape are easy to adjust simply by dragging the relevant adjustment point.

                      See here (start at 55s): A few of the routing tools available in CADSTAR - YouTube


                      Supplementary question: is lengthening available for differential pairs? When I try to route a diff pair, then shift-A does not seem to work.

                • Re: route lengthening
                  Injy Gadalla

                  Hello Graeme,


                  From the home menu, under the Select command, you have the option to select connected copper.  This option will allow you to select all routed tracks and electrical objects connected to the same net.  Once it is selected you can edit the properties as a whole using the PCB Inspector panel. In the Inspector click the all types of objects to just limit the edit the tracks. Once you edit a field the changes will propagate to all selected track objects.




                  Hope this helps



                  • Re: route lengthening
                    Markus Olsson



                    Where do you define the length rule?