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Sajith_K_Intel's avatar
Sajith_K_Intel
Icon for New Contributor rankNew Contributor
6 years ago
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How do we set a "keep" or "preserve" attribute to a wire, from QSF or without modifying the code?

How do we set a "keep" or preserve attribute to a wire in my design, from QSF without modifying the code?

Quartus 19.4 have PRESERVE_REGISTER setting, but for registers. What I would like to place attribute is on a wire. The wire name is getting changed due to packing/merging to LUTs and other combo nets.

4 Replies

  • KhaiChein_Y_Intel's avatar
    KhaiChein_Y_Intel
    Icon for Regular Contributor rankRegular Contributor
    5 years ago

    Hi,

    Yes. The attribute preserve is supported through HDL only.

    Thanks.

    Best regards,

    KhaiY

  • sstrell's avatar
    sstrell
    Icon for Super Contributor rankSuper Contributor
    6 years ago

    Unfortunately, I don't think this is possible without using a synthesis attribute in the code. However, have you tried preserving the registers before or after the logic where you're seeing the name changes?

    And if you don't want the packing and merging you mention to occur at all, look at some of the logic options/assignments that start with "Auto" that might prevent the changes from happening.

    #iwork4intel

    • Sajith_K_Intel's avatar
      Sajith_K_Intel
      Icon for New Contributor rankNew Contributor
      6 years ago

      @sstrell​ it did not work as expected. Also since the design is large, there are multiple registers on either side of the node. it is hard to put preserve on those every registers.

      I was wondering why Quartus do not support this feature, while they support it through HDL modification.