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jamesjisun
Visitor
Visitor
5,625 Views
Registered: ‎08-13-2011

can I specify which interconnection to use during synthesis?

Hi there,

 

I am wondering if I can ask the synthesis tools to use interconnection I prefer? such as if there is long wire available, please use long wire instead of doublewire or other kind of wire.

 

Thanks,

J

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7 Replies
eteam00
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Registered: ‎07-21-2009

Not as far as I know.  Why would you want to do such a thing?

 

-- Bob Elkind

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jamesjisun
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Registered: ‎08-13-2011

Hi Bob,

 

Thanks for the reply. I want to use long wires to compare the performance of my design with short wires.

 

Cheers,

J

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joelby
Advisor
Advisor
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Registered: ‎10-05-2010

I doubt there's much call for a parameter to do this, but you can fiddle with the routing of your design using FPGA Editor, and to make the changes a bit more permanent, add user constraints for the routing.

 

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jamesjisun
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Registered: ‎08-13-2011

 


@joelby wrote:

I doubt there's much call for a parameter to do this, but you can fiddle with the routing of your design using FPGA Editor, and to make the changes a bit more permanent, add user constraints for the routing.

 


Yeah, I am trying to do this.  However, it's too complicated in FPGA editor. I can point out which long line I want to use, but it's hard to get it routed to a specific SLICE. Is there a way that I can select long line and let it autoroute for the rest of the path instead of the whole path being rerouted?

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joelby
Advisor
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Registered: ‎10-05-2010

You could do something crazy, like wire two pins on the far side of the FPGA together and use them as an input and output.

 

That should give you a large routing and pad delay, which is even adjustable if you have a big spool of wire.

 

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jamesjisun
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Registered: ‎08-13-2011


@joelby wrote:

You could do something crazy, like wire two pins on the far side of the FPGA together and use them as an input and output.

 

That should give you a large routing and pad delay, which is even adjustable if you have a big spool of wire.

 


actually, in that case, FPGA editor's autoroute will utilize short wires to be segmented instead of a long wire placed...

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joelby
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Registered: ‎10-05-2010

Sorry, I think I was taking the definition of 'long wires' a bit too literally.

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