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ERROR: (IMPSP-9099): Scan chains exist in this design but are not defined for xx% flops

Hi there,

I have a small design (basically a counter) which latches the output to multiple different registers at time.
So I guess that Genus is using Scan FFs with their Enable input to select the active output FFs.

The use of those FFs with Scan functionality causes Innovus to fail:

ERROR: (IMPSP-9099): Scan chains exist in this design but are not defined for 54.84% flops

However, when I forbid genus to use them by
set_db use_scan_seqs_for_non_dft false
then it works fine but my design becomes 50% larger.

So I don't want to do it, but how can I route the design in innovus then? It it sort of strange, doing this for 15 years now but never had this issue.

It sais it has DFFs with scan functionality, but there is no scan chain defined. So I can't delete it, because there is non...

Thanks for any hints,
Joachim

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JayBee over 2 years ago

Apparently, I was able to fix it by setting:

setPlaceMode -place_design_floorplan_mode true

But I have no idea which other implication that has.
Only thing I noticed is that I have to set it back to false immediately after the initial place, because otherwise routing is creating DRC errors.

Maybe somebody has any idea or suggestion what I could do better...

Cheers and thanks !
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DimoM over 2 years ago in reply to JayBee

Hi Joachim,

does the rest of the design have a scan chain ? If this is not the case you can use the following switch:
setPlaceMode -place_global_ignore_scan false

Taken from here: Placement aborts with IMPSP-9099/IMPSP-9100 error if scan chains are not completely defined in the design or missing scan chain

It seems like the option you are using now is only for feasibility checks:
"Runs placement in the floorplan mode. This mode is used for prototyping and runs quickly to gauge the feasibility of the netlist, but might not place design components in legal locations."

- Dimo
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JayBee over 2 years ago in reply to DimoM

Hi Dimo,
thanks for your help!
You are totally right, the floorplan option that I am using right now is not good, because it does not place nicely and relies on the router to fix it.
Your solution is *much* better! When I saw it, I immediately thought I had seen and use this before, but I could not recall.
Thanks again, Joachim
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JayBee over 2 years ago in reply to DimoM

Hi Dimo,
thanks for your help!
You are totally right, the floorplan option that I am using right now is not good, because it does not place nicely and relies on the router to fix it.
Your solution is *much* better! When I saw it, I immediately thought I had seen and use this before, but I could not recall.
Thanks again, Joachim
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