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<@U018LA3KZCJ> Not sure if this makes sense but can I tell openroad to route a specific wire in a pa...
# openroad
s
@Matt Liberty Not sure if this makes sense but can I tell openroad to route a specific wire in a particular layer? If so, how can do that?
h
Same here, I would be highly interested in that. I would like to specify layer and width, that would be super helpful for analog integration in digital-on-top.
m
There isn't a way to specify layers per net today. We do allow clocks vs signals to be specified at global routing. If it is important open an enhancement request to OR in GH. What is your use case?
h
My use case is: I assemble a top-level chip design completely in OR. I have analog/mixed-signal macros, where I want the analog signals to be routed by OR, to avoid having manual and automatic routes mixed. These analog signals should be pushed to higher layers, plus they should be wider to lower resistance. So I would like to be able to say, “hey OR, this is an analog signal, route this first and as efficient as possible, and please use met3 and up, and make it 2um wide.”
Maybe a useful alternative would be to provide a DEF with manual routes that should be used by OR between placement and routing so that I can intercept the flow with manual analog routes efficiently.
m
For layer width you can use create_ndr though it hasn't had a lot of usage yet
You should be able to create manual pre-routes and feed them to OR. There isn't any automation for that flow but we already avoid fixed objects in the power grid so it wouldn't be too different.
m
@Matt Liberty Can you point out a snippet where CTS nets are being assigned higher metal layers? I Remember we did that for BP but I can't seem to find it.
It seems like it is hardcoded here for clock signals, can we make it generic? Would you accept a PR for that? Example: 
set_routing_layers -signal Metal2-Metal10 -clock Metal6-Metal9
or maybe we could add a -power option?
m
@mehdi your example is already accepted: set_routing_layers [-signal min-max] [-clock min-max]
s
@Matt Liberty How to use this command to route special signals other than clock? Is it possible?
m
It isn't possible for other nets today
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