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Moving DFA constrained parts

Pkeefie

  All,

We use to add a 15 mil overage to our Place_Bound for every footprint to acomadate our assembly vendors 30 mil min between components. All of our parts are now being created with a DFA shape that is the same size as the actual part. I then set the constraints to be 30 mil part to part and the place_bound is the same size as the DFA shape. Now when I move the parts after a quick_place I can't tell if I'm to close to a part till I move it a few times to see the DRC, then I have to move it away to clear the DRC.

  Am I missing something or do I have to move each part 3-5 times to get it in the right location without being to far way from another part. With my old Place_bound I could just butt them up against each other and see that they were not to far away from each other. Does anyone use this feature in Allegro? I can't go back to the "old" days and place using a .025 grid, parts will be to far apart.

 Thanks

paulk

  • mcatramb91

    Paul,

    If everything is setup correctly you should get real time feedback as you violate the DFA Clearance while the component is on your cursor.  By real time feedback I mean you would see a bubble appear between the DFA Boundaries and a slight pause in the component movement indicating a minimum clearance condition before placing the component.  You have to be in Place Manual to see this feedback and you do not get any feedback when using Edit > Move to move components.

    Hope this helps,
    Mike Catrambone

     

  • Pkeefie
    Mike, That's my point, I'm in Edit>Move and as far as I can tell I'm guessing the correct location to avoid the DFA / DRC. Are you using this feature yourself? I would think that folks would be screaming for real time feedback during edit > move! Maybe everyone gets the placement right the first time with Place_manual. :) maybe I shouldn't be smiling! I'll typically do quick place to rooms or just pick them off the schematic but I always have to move them. I see people looking at the topic on line but I'm still not convinced many folk are using this feature. Some one suggested I use a 25 mil grid to move parts but they will be to far apart and I'll feel like I'm back in 1982 using Sci-Cards :)

      This is what I see now, the DFA shape is purple.

      This is what I was looking at with my old library, if I overlap a place_bound I get a DRC but I can actually see what the bound location is.

    Thanks for your very quick response but I'm still lost.

    paulkeefe

  • mcatramb91

    Paul,

    In order to see the real time feedback you need to use Place Manual.  I have heard users complain about this when the DFA Checks were first rolled out but since then Cadence adding functionality to hide the Place Manual window or execute the command with seeing the window at all using Place Manual with the -h switch.  There is also a icon to execute the place manual command with the -h switch - icon looks like a Quad Pack with U1 in the middle, just mouse over it and you will see a tool tip with says "place manual -h"  When you are in place manual you have the ability to select a component to move it where ever you like so it acts the way Move does.

    I have been using the DFA checks for a while now and it did take time getting use to using Place > Place Manual instead of Edit > Move but it made it much easier with the ability to hide the Place Manual window.  I did not see your images from your last post for some reason, please reply and attach them to the post using the options tab.

    Hope this helps,
    Mike Catrambone

  • edhickey

    Paul,

    Please use the Place Manual-H Icon as Mike suggested to get DFA feedback while moving components. This command also supports mirror and rotate on the RMB menu. If using 16.2, it's even easier. Go into Place Application mode and just make a single LMB pick on a component to move it, use of icons or menu paths is not required.

    One other note on DFA. You may experience some level of resistance when the clearance bubble appears. This is controlled by a user preference variable called dfa_pause_level. The range is 0 -3 (least to most resistance).

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