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I understand what do the global & detailed placement as it can be seen visually but about the routing. I'd say global routing prepares some information for detailed placement. What are this information? Is there some info that summarizes what the global route does? |
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Replies: 3 comments 10 replies
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The global router's job is to resolve routing congestion by giving general guidance to the detailed router. That guidance is in the form of 'guides' which are layer-assigned rectangles that the net should be routed within. If all nets are routed inside their guides the hope is that the detailed router will not hit an area that is too dense to route. The detailed router then tries to implement the nets inside their guides considering the full set of DRC rules. It is possible that it still can't find a solution within the guide and may deviate outside if necessary. The detailed router in OR has a global router built into it. We don't recommend you use it as it is rather untested and suggest you instead ues the global_route command. It will be used if no guides are provided. |
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Ok. Thanks for the explanation. |
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@titan73 here are some slides from my class on global vs. detailed routing. Hopefully it can add to what @maliberty said |
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Thanks for the doc. |
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Is there a way to visualize these guides? |
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I have a routed net selected, but it seems that reading a routed def followed by global_route won’t get me the guide button. |
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If the net is already routed there is nothing for the global router to do and no guides are generated. |
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Thank. |
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You can click the guides button again to turn them off for the selected net. If you right click in the layout there is a pop menu with the choice to clear all guides (and various other things). |
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Works fine. Thanks |
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The global router's job is to resolve routing congestion by giving general guidance to the detailed router. That guidance is in the form of 'guides' which are layer-assigned rectangles that the net should be routed within. If all nets are routed inside their guides the hope is that the detailed router will not hit an area that is too dense to route.
The detailed router then tries to implement the nets inside their guides considering the full set of DRC rules. It is possible that it still can't find a solution within the guide and may deviate outside if necessary.
The detailed router in OR has a global router built into it. We don't recommend you use it as it is rather untested and suggest…