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RE: SDF generation problem

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Hello Kari,

I’m trying to generate an SDF file in Encounter for backannotation, using the Timing>Calculate Delay command. My problem is that the resulting SDF file has the same value for min, typ and max delays, for example:

(INTERCONNECT I1/I0/I16/Z I1/I0/I14/A1 (0.0003:0.0003:0.0003) (0.0003:0.0003:0.0003))

Or

(CELL

  (CELLTYPE "CKND2D2")

  (INSTANCE I1/I7/I18)

  (DELAY

    (ABSOLUTE

      (IOPATH A1 ZN (0.0247:0.0247:0.0247) (0.034:0.034:0.034))

      (IOPATH A2 ZN (0.0382:0.0382:0.0382) (0.0464:0.0464:0.0464))

    )

  )

)

This is true for both SignalStorm and Encounter’s Delay Calculator. I tried to change the PVT conditions with setOpCond BCCOM | WCCOM | NCCOM but I’m getting the same numbers.

Please assist me with this. Thank you in advance.

 
Best regards,

Alex

IC Design Engineer
Parents
  • Hi Kari,

    No I haven’t set up MMMC, but what I found (strangely enough) is that running Timing>Calculate Delay gives a different SDF file from running write_sdf in the encounter shell! Using the write_sdf command produces a file with min and max values:

    (CELL

        (CELLTYPE  "CKBD2")

        (INSTANCE  CLK__I7)

          (DELAY

                (ABSOLUTE

                (IOPATH CLK C  (0.0259::0.0623) (0.0267::0.0614))

                )

          )

      )

    I’m guessing that the typ values are missing because for some reason Encounter won’t accept my vendor’s typ timing library although it is specified in the conf file. I can tell that this is so because when I do Design>Import after the design is already imported, the ‘Common Timing Libraries’ slit is empty. Any idea why this is happening? Note that I dont get any errors or warnings regarding the typ library when I import the design.

    Back to the SDF issue, what I also found is that some delay values are different in the SDF file produced by Timing>Calculate Delay and in the one produced by write_sdf:

    For example:

    (INTERCONNECT I1/I0/I16/Z I1/I0/I14/A1  (0.0000::0.0000) (0.0000::0.0000))           -- SDF file produced by write_sdf

    (INTERCONNECT I1/I0/I16/Z I1/I0/I14/A1 (0.0003:0.0003:0.0003) (0.0003:0.0003:0.0003))    -- SDF file produced by Timing>Calculate Delay

    I find this rather weird because both methods for producing the SDF file use the delayCal command.....

    Thanks for your (always) prompt response,


    Alex
Reply
  • Hi Kari,

    No I haven’t set up MMMC, but what I found (strangely enough) is that running Timing>Calculate Delay gives a different SDF file from running write_sdf in the encounter shell! Using the write_sdf command produces a file with min and max values:

    (CELL

        (CELLTYPE  "CKBD2")

        (INSTANCE  CLK__I7)

          (DELAY

                (ABSOLUTE

                (IOPATH CLK C  (0.0259::0.0623) (0.0267::0.0614))

                )

          )

      )

    I’m guessing that the typ values are missing because for some reason Encounter won’t accept my vendor’s typ timing library although it is specified in the conf file. I can tell that this is so because when I do Design>Import after the design is already imported, the ‘Common Timing Libraries’ slit is empty. Any idea why this is happening? Note that I dont get any errors or warnings regarding the typ library when I import the design.

    Back to the SDF issue, what I also found is that some delay values are different in the SDF file produced by Timing>Calculate Delay and in the one produced by write_sdf:

    For example:

    (INTERCONNECT I1/I0/I16/Z I1/I0/I14/A1  (0.0000::0.0000) (0.0000::0.0000))           -- SDF file produced by write_sdf

    (INTERCONNECT I1/I0/I16/Z I1/I0/I14/A1 (0.0003:0.0003:0.0003) (0.0003:0.0003:0.0003))    -- SDF file produced by Timing>Calculate Delay

    I find this rather weird because both methods for producing the SDF file use the delayCal command.....

    Thanks for your (always) prompt response,


    Alex
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