1. Home
  2. Field-Programmable Gate Arrays
  3. Timing constraints not applied, ISE & SynplifyPro

Timing constraints not applied, ISE & SynplifyPro

Hi,

I'm a new synplify pro user. This tool seems to be much powerfull than XST for apply timing constraints. But there is something I don't understand : in the synplify pro report, I can see all my timing constraints, and design meets timing requirements. After that, using Synplify pro interface, I launch ISE Place & Route.. When P&R finishs, I look at the report, and I can see all my timing constraints, but for the most importants, I can read : N/A. ISE tells me it can't apply my constraints.. I will understand if it tells me timing were not met, but why can't it apply them ? is there a problem between synplify pro and ISE ? why synplify can't pass my constraints to ISE ?

Thank you by advance,

Best regards, Michel.

Reply to
michel.talon
Loading thread data ...

Open a case with Synplicty.

Communication of constraints from synthesis to place and route and vice-versa is one of the downsides to separate synthesis.

I prefer to apply detailed constraints at the backend.

-- Mike Treseler

Reply to
Mike Treseler

I, too, apply my constraints primarily in the back end. What I've seen in both the constraints passed from the Synplify tool and from applying constraints exclusively in the back end, many constraints end up on a generated net (such as the output of a DCM) rather than the net specified in the original constraint. The result is an "N/A" listing for the constraint specified but a different nearly identical constraint that applies to all the registers (typically) that you intended.

It may be ISE rather than SynplifyPro that's supplying the confusing information.

- John_H

Reply to
John_H

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.