Novel autorouter tackles topology - not shapes

Altium has unveiled Situs, its next-generation Topological Autorouter that will be included in the upcoming version of its Protel board-level design system.

Altium has unveiled Situs, its next-generation Topological Autorouter that will be included in the upcoming version of its Protel board-level design system.

The Situs autorouter breaks new ground for the PCB industry as it incorporates Altium's next-generation Topological Autorouting technology, which allows designers to move beyond the constraints of current shape-based technologies.

The advanced features and functionality of Situs combine ease of use with layered levels of control to give all designers the level of detailed control they need.

The name Situs comes from "Situs analysis", a branch of mathematics that is the study of the properties of geometric figures or solids that are not normally affected by changes in size or shape, commonly known today as topology.

Altium reckons Situs marks the beginning of the next generation in routing - Topological Autorouting - a technology that moves beyond traditional rectilinear shape-based routing by adding a topological board-analysis stage to the autorouting process.

Traditional shape-based routers tend to construct their initial model of a PCB based on the overall position and shape of each object on the board.

In addition, many autorouters are limited to looking at objects as rectangular shapes.

With Situs, the PCB is initially modelled by the spatial relationships of each object relative to another, without reference to their size, absolute position or shape.

Situs uses this topological analysis to perform its path-finding functions.

Because Situs considers only the relative position of objects, it is free from the artificial geometric constraints suffered by shape-based routers.

It does not need to know how to route between two objects to choose a path; it only needs to know that a path exists.

This flexibility allows Situs to easily cope with nonstandard board and component configurations and establishes more intelligent and natural routing paths on the board.

Once routing paths have been established, they are mapped back to a more conventional shape-based space for inclusion in the PCB design.

With this approach, the paths for routing can be any size, angle or shape and only need to be mapped back to the PCB design as a last step.

This topological approach frees Situs from the constraints of orthogonal rectangular shapes and allows better use of board real estate and more efficient routing on high-density boards.

Situs topological autorouting also offers more promise for current and future board and packaging technologies, such as blind and buried vias, staggered grid, high-density BGAs and so forth.

Topological Autorouting also minimises rework on autorouted boards.

A common criticism of current-generation shape-based routers is that the boards they produce have an unnatural autorouted look.

The initial topological analysis made by Situs allows it to construct much more natural routing paths.

By using its native 45-degree and any-angle routing abilities, as well as intelligently assigning connections to layers, Situs effectively routes boards and components of any geometry without introducing illogically placed tracks that need to be rerouted later.

An extensive series of smart cleanup passes increases the natural look of boards routed with Situs, leading to aesthetically sound results with a minimum of postroute cleanup work.

This promises significant time savings for designers, significantly reducing overall development costs.

Situs will be included with the next generation of Altium's Protel board-level design system, due for release in Q1 2002.

Situs will be fully integrated with the Protel PCB layout and editing environment and will operate directly on the Protel PCB design database, completely eliminating design rule and design data translation issues.

This high level of integration means that Situs will also include far more extensive support for the Protel PCB design rule system than was previously possible.

Situs will support all Protel design rules and scopes, with the initial exception of some high-speed rules.

Support for these remaining high-speed rules is expected to be included in future updates.

One of the core design requirements set for Situs was that it offered a high level of routing control while being easy to set up and use.

This goal has been achieved through the use of layered levels of control.

Designers can either allow Situs to automatically set all parameters and strategies based on its analysis of the board configuration or manually control routing using unique and intuitive parametric "tradeoff" controls that allow them to set preferences and adjust costings - via count, for example, over routing length.

While Situs offers experienced users the depth of control needed to tackle any routing task, the multilevel control options also ensure that inexperienced designers will be able to achieve good results with Situs straight out of the box.

Pricing for the new version of Protel is expected to be in line with the current Protel 99 SE pricing model.

Existing Protel customers who are members of Altium's recently announced Altium Total Support (ATS) programme will be shipped the new version, which includes Situs, free of charge as part of their ATS membership.

As previously announced, all new Protel 99 SE full suite licenses come with 12 months free membership to Altium Total Support (valued at US$1995), which guarantees free access to the next Protel version, including the Situs autorouter when it is released.

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