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Explorer
Explorer
8,041 Views
Registered: ‎03-18-2008

ISE Intelligent script

who can provide the script?

If the current P&R timing is not meet,and the ISE can re-implement based the initial constrain with 0.01ns step add/sub automatic until the timing ok?
So that the ISE can always work no manualy intervention.

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Professor
Professor
8,033 Views
Registered: ‎08-14-2007

Re: ISE Intelligent script

I'm a little confused by your wording.

 

Do you mean to vary the timing constraints  in steps until the design passes.  In that

way to find the "best" achievable timing?

 

Usually constaints are understood to be absolute requirements.  e.g. some external

device MUST have outputs 3 ns before the next clock edge or your design will not

work reliably.  Changing the constraints means changing the system level design.

-- Gabor
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Explorer
Explorer
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Registered: ‎03-18-2008

Re: ISE Intelligent script

I only have a critical timing. Eg: my constrain requirement is 8ns.if it is not meet,i wish the script can subtract a 0.01ns step base 8ns.(7.99,7.98,7.97...........) until the timg is ok.then,it can stop.So, i wish get the correct result in the morning through the whole night P&R work .
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Professor
Professor
7,951 Views
Registered: ‎08-14-2007

Re: ISE Intelligent script

Generally speaking, reducing the constraint time does not help to meet timing.  If you find that

changing timing by .01ns at a time helps, the real mechanism that helps is using a different

random seed for the placement.  I would suggest just trying multipass P&R with a constant

constraint value of 8ns.  You don't need a special script for this.

 

Regards,

Gabor

-- Gabor
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Explorer
Explorer
7,859 Views
Registered: ‎03-18-2008

Re: ISE Intelligent script

So,it will auto finish if timing is closure?

 

However,it is ok if there is a option intelligent script

 

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Historian
Historian
7,817 Views
Registered: ‎02-25-2008

Re: ISE Intelligent script


m006 wrote:
I only have a critical timing.Eg: my constrain requirement is 8ns.if it is not meet,i wish the script can subtract a 0.01ns step base 8ns.(7.99,7.98,7.97...........) until the timg is ok.then,it can stop.So, i wish get the correct result in the morning through the whole night P&R work .
I'm not sure I see the benefit of your script.
 If my period constraint is 8 ns, and if I meet it, I don't care if it can also run at 7.99 ns or whatever.
 And if it does NOT run at 8 ns, the fact that it DOES run at 8.1 ns isn't helpful, either.
 -a 

 

----------------------------Yes, I do this for a living.
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Explorer
Explorer
7,800 Views
Registered: ‎03-18-2008

Re: ISE Intelligent script

As long as the timing can archieve within 8ns. then,stop retrying and generate bit file

 

it is ok.

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