Tco Constraints

Hi Ardni

Sorry for the late reply.

Having checked the help, cliques only work on ACEX 1K, FLEX 10K, FLEX 6000, or Mercury devices. You're using a Flex10k right?

Basically you can assign nodes of a design to a defined "clique" - from memory you have to give the clique a name and then assign nodes to it. Members of that clique are then placed in the same LAB or row (depending on what you set). E.g. define a new clique called "My_clique" with all its members being placed in the same LAB. Then where you have large delays between two nodes that aren't quite meeting your timing, add those nodes to the clique and Quartus will place them in the same LAB which will reduce their timing delay. If they are already in the same LAB before you start then don't bother - the clique won't make any difference.

Sorry it's a bit vague - I haven't done it in years.

I'm sure you should also just be able to make a location assignment and assign nodes to a certain row (or possibly even a particular LAB). Try fixing your critical logic elements that don't meet timing to the row right next to the device pin.

For anything you do you'll need to look at the floorplan to see where the delays are and also only change one thing at a time - it will have other knock on effects. From memory when I've done this I haven't had more than about five such assignments. If you change your design (source code) then you'll probably have to delete these assignments and start again.

It's not an easy solution and will only really be effective if you're pretty close on just a couple of paths. if you've got a screen full of timing failures then this approach probably won't help - you'll just waste a few days chasing your tail.

Good luck