Stats

  • Locked Locked
  • Replies 12
  • Subscribers 166
  • Views 19325
  • Members are here 0
More Content
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Creating Rat Ts pin pairs for Total Etch Length constraint

mvonahnen

 It is possible to create pin pairs for the Total Etch Length constraint?  I have a DDR configuration where I need to match the length of the address signals which are branched to multiple chips (4) to the length of the data lines that are a point to point signals.  It is straight forward how the match the signals within the groups (address, cmd, and data) but it is not clear how to match the groups to each other, which is a requirement.

  • redwire
    Cadence covers this example in their Constraint Manager User's Guide.  Look at "Match Groups" in the index. Scroll on down and you'll see how to get busses to match with individual match properties set within the groups.  DDR is explicitly covered.
  • mvonahnen

     Thanks, I have looked over this.  I take it from your response that there is no way to create pin pairs for Total Etch Length?

  • redwire

     Lock in a target on total etch with a single net pin pair and the relative will follow.

  • mvonahnen

    I guess you are missing the point.  I need to match a tree structure with a point to point.  It is straight forward to match pin pairs in relative distance, but how do you match a combination of 3 pin pairs to a single line?  My intent was to specify each of the legs independently and the sum of their distance would be the specification for the data line.

     Other than a two stage routing (once using relative for the tree structure and a second for the point to point lines), I don't see how this can be specified.

  • Khurana

    >>how do you match a combination of 3 pin pairs to a single line?

    Create another match group which is inclusive of 3 pin pairs and single line (single line will also be a "pin pair" since you said it's point to point).

Cadence Guidelines

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.