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Five-Minute Tutorial: Selective Blockage In EDI 11

Comments(3)Filed under: encounter, EDI, five minute tutorial, EDI 11, selectiveBlockage, setPlaceMode, placement blockage, Encounter Digital Implementation11, EDI 11.1, selective blockage
Today I'd like to highlight one of the new features in Encounter Digital Implementation System (EDI) 11: selective blockage. Everyone has used placement blockages before; most of us have used soft blockages also. (As a quick review, a soft blockage is a placement blockage that will keep blocks and cells from being placed there during placement, but cells may be placed there during any ecoPlace/refinePlace, CTS, or optDesign steps.) This is fine for most purposes, but sometimes we want a little more control over what gets placed in the area of a soft blockage.

To use selective blockages, create your soft blockages as you normally would, then set the following:

setPlaceMode -selectiveBlockage true

Setting this variable to true means that by default, buffers, inverters, isolation cells, and level shifters are allowed to be placed inside the soft blockages, as well as any other cells that you optionally specify. If you wish to specify more cells or instances that you would like to allow in the soft blockages, you set the following:

specifySelectiveBlkgGate -cell masterCellName 


specifySelectiveBlkgGate -inst instName

or all in one command:

specifySelectiveBlkgGate -cell masterCellName -inst instName

You can use wildcards to make things easy.

For example, let's say that you have an area that you don't want any functional cells to be placed in, but you do want filler cells to be placed there during your filler cell step. You could do this:

specifySelectiveBlkgGate -cell FILL*

You can also specify cells that you don't want to be placed in the selective blockage:

unspecifySelectiveBlkgGate -cell masterCellName -inst instName

What are some creative uses of selective blockage that you have in mind, or have wished you could do in the past? I'd love to hear some ideas in the comments!

- Kari Summers


By fitz on July 5, 2012
Power grid via stack arrays cause a lot of vertical signal routing congestion.

You will improve routability if you can keep standard cell signal pins out of this via shadow.

In the past I have used vertical soft blockages aligned to all the via stacks.

Now I will try the same thing but allow low pin density cells ( ie.registers )  into the via shadow and keep the nasty cells (ie. aoi222 ) out.

refinePlace should be enhanced to automatically consider / limit the number of signal pins in the via shadow.

By Abhishek Chhajer on December 21, 2012
1. during prects it simplify netlist is set to true then it donot add the new cell in the selective Blockage list.
             For eg. if there is OR and AND cell in series... then the tool may replace it to AO cell. but this AO cell doesnot sit in the blockage area.  (creating problem in my case)
this problem need to be solved.
2. there should be option that the complete path can be set in the selective blockage

By Kari on December 21, 2012
Hi Abhishek, Thanks for the comments. I'm not sure what you mean by a complete path in your second item. For the first one, yes - EDI will not anticipate how the logic may get changed, so you'll have to include that celltype if you want it to be part of your selective blockage flow. I encourage you to file an enhancement request if you feel strongly about this behavior.

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