User Defined Scan Reorder in placement

[asinghct]

HI,
I want to scan-chain reordering after placement (or in placedesign) in a manner given below
Suppose I have two scan-chains 1 and 2
Chain 1 (3 flops) - a, b, c
chain2 (3 flops) - d e f

What I need is to re-stitch chains in a given order (defined by user ) for example in this case chain 1is now a, b,d and chain 2 consists of
c e f.

Due to some issues I want to restitch chains in a definite order, a typical scan-order does is only placement aware and reduces wire length,
However, in my case wire length is not an issue and I want a user defined scan-chain stitching after placement.

Pls note that grouping the scan-cell so that they are kept together while re-ordering will not work here as, scan-chain that we are getting from front-end
dft flow (in scan def) is different from the user defined chains that we want post placement.

I am using cadence soc encounter and have acess to mentor tools also
Thanks
Kumar

 

[lostinxlation]

I don't know if backend tools can do that, but if I were you, I'd write a perl (or wahtever language) script to modify the scan chains in netlist or def file and reroute the new nets on the backend tool.

 

[ConradATPG]

Most scan stitching software will accept a list of flip-flops and stitch the chains in that order.