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Why net parasitics is not annotated?

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kumar_eee

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Hi,
After reading the SPEF, when I run "report_annotated_parasitics" command, it shows few nets are not annotated.

Why the parasitic is not annotated?

Rgds,
KK
 

matter

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If you are using recent versions of PT, they have parallelised the parasitics reading section. So try an update_timing or report_timing command and then do your report_annotated_para.
read_para ...
read_sdc
update_timing
report_annotated_para ...
 

birdy123

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hi matter, I think kumar is asking the reason of "few" nets.. My point whatever you have mention is 100% correct but looks like kumar question is not with respect to all the nets .. its for few of the nets...

Kumar , before suggesting you any thing .. I would like to know the error/warning messages. There may be several reason that a particular net/ set of nets are not annotated..
Can you just post 2-3 message here for my referance?
 

matter

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Hi Birdy123, Yes, you are correct. I missed the "few nets" detail in the original post. Looks like you are helping in the right direction.

Regards
 

kumar_eee

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Hi Guys,
I followed the following steps as per my company CAD flow.

1. SPEF extracted from QRC tool.
2. Reading the SPEF in Gold-Time/ETS.
3. Run the "report_annotated_parasitics" command to find the status.

Step 3 gives me a kind of statistics like Total nets, Nets annotated, Nets not annotated.

My Question here is, When you dump the spef, it should contain the parasitic details for all the nets. I hope everyone agree with me.
But, I could find a few nets are not annotated after step 3.

What could be the reason for not annotating or parastics not available for few nets?

Rgds,
Kumar
 

matter

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Kumar, I am not familiar with Goldtime. But based on my exp with PT, it is possible that there can be nets without annotation. Most of the EDA tools work the same way, so I am guessing that the report_annotated_para command in Goldtime should have given you some reason as to why certain nets are not getting annotated. Generally PT's report_annotated_para command will give reasons like Driverless nets, Loadless nets etc. Try using the -verbose if available in goldtime to get more details for debugging.
 
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