Today there are many methods to address transmission line routing techniques. One of those is the Auto Route feature found in Siemens PCB Layout products which allows rapid routing connections that references established board parameters and constraints rules. In this portion of the Routing Methodologies and Best Practices webinar, basic methods and approaches will be demonstrated, proven, and captured for reuse.
- Installation Flow / Licensing
- Auto Routing Pass Types
- Memory
- Fanouts / No Via or Bias
- Tune Delay
- Partial Route
- Tune Crosstalk
- Net Ordering
- Post Route
Questions and Answers from the Webinar:Question: Does the Auto Router use Sketch Routing?
Answer: No, Sketch Routing is considered to be Auto Interactive Routing.
Question: Can created schemes be used by other users?
Answer: Yes, schemes can be saved to a user defined location that can be shared to other users.
Question: Does the Auto Router route Any Angle or Curved Traces?
Answer: No, Any Angle angle routing is an interactive Plow method only and Curved traces are Interactive or post routing Miters can be added after Auto Routing.
Question: Should I Fanout the entire board first?
Answer: It is not required, but for some designs the user may find that having a Via in place prior to routing may provide for better completion.
Question: If I choose a Layer in a Scheme, does it override Layer choices in Constraint Manager?
Answer: No, Constraint Manager wins and drives all rules within the Auto Router.
Question: Can I with avoiding vertical parallel routing and avoiding crosstalk by maximizing the space that you have fenced off?
Answer: Maybe incorporating data from HLDRC? A: Routing is based on rules within Constraint Manager. HLDRC is a rules checking system and is not recognized by Constraint Manager. Based on clearance in Constraint Manager, the Crosstalk pass in the Auto Router will flag areas and separate traces of the design that do not adhere to your Crosstalk or Parallelism rules.
Question: Why do all autorouters have routes hug each other? If you have the room use it. This example has a lot of empty space and unnecessary hitches in the routes.
Answer: The shape based router looks for the shortest transmission line path available. The router does provide post processing route passes for Via Reduction, Smooth and Spread, to better provide clearances for Design for Manufacturing. Note: The Smooth pass should not be used on Differential Pairs as it may separate the routed trace pairs.
Question: Is there possibility to auto-route all the way from surface to base layer?
Answer: Yes, based on the selection of layers in the Auto Route scheme, and the available enabled layers in Constraint Manager, the Auto Router will route the connection to completion using the layers needed.
Question: How does it do with Class to class routing of diff pairs and match sets to each other?
Answer: It will route all traces based on the Class to Class rules and Matching rules within Constraint Manager.
Question: So a side file is no longer used/needed for spread pass?
Answer: The side file can be used if you wish to increase the Spread of specific traces by more than 2X, which is the default state without a side file. This work only when the Spread Pass type is used in a routing scheme.
Question: Do route fences need to be built into the layout before you attempt to use the auto router?
Answer: Yes, these can be used to constrain critical signals or busses to specific areas of the design, including adjacent layers.
Question: Does using COM scripting for automation invoke the same AutoRoute engine that the Layout GUI utilizes?
Answer: Yes, the automation available today works with the AutoRouter engine.
Question: Is there a difference between the autorouter Tune Crosstalk and using the Resolve in the hazard explorer on those nets .... they both seem to use spacers.
Answer: Yes, one is tuned for interactive performance, one is not. You can get different results using Auto Route Tune Crosstalk compared to Resolve in Hazard Explorer. THe same engine is used with different characteristic input.
Question: How do you determine what via is used for the fanout and route scheme?
Answer: The Vias set in Setup Parameters and/or Net Classes in Constraint Manager drive the vias used in fanout and routing.
Question: Hi thank you for the presentation. How are your experiences with e.g. Auto Routing 5 DDR4-Memories? I have issues with tuning with Auto Router, because the tool starts with any net, tunes everything as long as there is enough space. So after a while, space runs out and one or to nets in the middle of a byte group wasn't routed and there is no space left. What would you try or what order of the functions (longest first...) would you recommend?
Answer: Although the Auto Router can route many complex topologies and circuits, density in some designs may cause the router to have a lower completion rate. Suggested methods for dense designs and complex routing may have better completion and success using Sketch Planning and Routing technology.
Question: Do you recommend using fences/routing in smaller groups to ensure that the auto router doesn't make it impossible to route remaining open netlines?
Answer: Depending on your design and density, using fences can constrain groups of signals to defined areas to keep them from encroaching unused area that may be needed for remaining nets?
Question: Should route and via grids be gridless?
Answer: Yes, the Auto Router is a shape based router and adheres to your clearance rules and provide much higher density routing when used gridless.
Question: Can you compare performance with specctra? Thanks
Answer: Not to compare to another competitor, but in comparing technology the Xpedition Auto Router is a true 45 degree and shape based, constraint driven routing system. Whereas other technologies in the past were conflict routers that although had good completion rates, they created thousands of drc errors that had to be post processed for completion of the design.
Question: So the questions on the class to class is can you neck down in areas as needed for connector and device routing where is conflicts with the class to class rule for diff pairs for instance.
Answer: For necking down of trace routing, the Auto Router uses clearances in the Constrain Manager for Route Areas, and also uses the Editor Control setting for Expansion and Minimization of trace routing widths.
Question: Will phase matching and noise rules be routed without violations?
Answer: Yes, we will not create clearance violations, but it is possible that other violations could be created like Match Length, etc.
Question: Is there any option to do Arc auto routing.?
Answer: Curved trace routing and mitering is a post process after the Auto Router completes.
Question: Is No Via or Bias the only pass that does not adhere to layer biases?
Answer: Yes, if you would prefer to route without Layer Directional biasing, the prefered method would be to use Sketch Planning and Routing techniques.
Question: If you turn off DRCs will it complete the auto route with errors?
Answer: The Auto Router completes routes based on the rules in Constraint Manager, with DRC off, the router will will not create DRCs.
Question: Are there more multi purpose, best practice autorouter schemes available for download for getting started quickly?
Answer: The Xpedition Tutorial has a few schemes available, and the demo material provided in this webinar will be made available with all of the schemes presented available for use.
Question: Is it possible to use the autorouter with Pads Pro?
Answer: Auto Router is not available in Pads Professional at this time.
Question: Speaking of rules areas; I assume the A/R respects rule areas?
Answer: Yes, all Rule Areas created in Constraint Manager are adhered to.
Question: How does autorouter handle overlapping rule areas?
Answer: Per normal usage of Rule Areas, if they overlap, the smaller of the Clearance rules in Constraint manager for a specific Rule Area is used.