[PCB_FORUM] Re: CONCEPT->CM->dcf->allegro?

Hi

Since I did not see any response to this thread, I thought I would put in my 
two cents worth.

Back where I used to work, they are using the "bogus allegro data base" also, 
shadow brd, for their electrical constraints only and then all other 
constraints are coming from Concept. I found using dcf files to transfer 
constraints was not always reliable as information such as target nets of 
relative-propagation-delay groups were sometimes lost. Using CM in Concept was 
tried but it was not able to understand xnets in Concept. You had to setup the 
xnets in Allegro and then back annotate the Concept. But with the schematic 
being the source of changes, keeping everything in sync was difficult. I 
understand CM in Concept is better now. The issue I have with having the shadow 
brd file is keeping track of what is the source of all the constraints.

If you are starting a new schematic, keeping track of the constraints in CM 
would be easier as the constraints in CM are different from the constraints 
entered by attributes in Concept. I believe the constraints in CM took priority 
but that may mean you may have unwanted constraints from attributes. It has 
been awhile since working CM and Concept so I do not know if much has changed.

My biggest issue with working with CM in Concept is that once Concept is 
"constraint manager enabled" there is no control of direction of the 
constraints. What was back-annotated from Allegro to Concept used to be 
controlled by the pxlBA.txt file. That is no longer the case after Concept is 
"constraint manager enabled. I have worked with Cadence on this issue several 
times and they do not consider this an issue. Maybe it is just me but I believe 
there should be one controlled source of all constraints. If there is any 
confusion of what the constraints should be, there is one source.

I hope I am not sounding too far-fetched of my expectations and if there are 
suggestions on what to do with my concerns, I am open to hear them.

Daniel
________________________________
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx 
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Hendrickson 
(jerryh)
Sent: Tuesday, August 22, 2006 3:23 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] CONCEPT->CM->dcf->allegro?


Hi all,
Is anyone entering Constraints in CM, in Concept? If so, are you exporting a 
dcf file and importing into Allegro? Or are you importing the CM information 
directly from the import logic? And, Have you seen any issues?

Currently our methodology is having the design engineers enter constraints in 
CM in a bogus allegro data base, exporting a dcf file and then have the CAD 
engineer import the dcf file into allegro. L


Thanks,
Jerry

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