# How to solve SDF error: cannot find timing check?

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#### anhtuan

##### Member level 4
I receive the message below when i run post-layout simulation with back annotation in VCS:
"SDF error: cannot find timing check"
Can anyone tell me how to solve this problem?

#### dft_guy

sdf cannot find timing check

That means that the cell library that you are using for simulation does not contain the timing check that is present in the SDF and is being annotated - or it may be present in the library, but timing checks are not enabled during compile time. The timing checks in the library are in the 'specify' block...

John
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#### anhtuan

##### Member level 4
find version of a sdf file

SDF file is error at the RECOVERY line. Here is a piece of code containing the error:

(TIMINGCHECK
(HOLD (posedge RN) (posedge CK) (-0.0581:0.0000:0.0000))
(RECOVERY (posedge RN) (posedge CK) (0.0000:0.3371:0.3371))
(HOLD (posedge D) (posedge CK) (-0.1019:0.0000:0.0000))
(HOLD (negedge D) (posedge CK) (-0.1210:0.0000:0.0000))
(SETUP (posedge D) (posedge CK) (0.0000:0.4512:0.4512))
(SETUP (negedge D) (posedge CK) (0.0000:0.6792:0.6792))
(WIDTH (negedge RN) (0.2730:0.6131:0.6131))
(WIDTH (posedge CK) (0.1224:0.2682:0.2682))
(WIDTH (negedge CK) (0.2244:0.4722:0.4722))
)

So i think the problem is: the cell library have not define the RECOVERY parameter (in specify block). Is that right?
The question is how to solve this error? Thank you!

#### dft_guy

back annotation with sdf 2.1 files

So i think the problem is: the cell library have not define the RECOVERY parameter (in specify block). Is that right?

Yes, that's right. Go take a look. Also, the SDF files from version 2.1 and 3.0 vary a bit. The cell library may be based on a different version than the SDF file. You'll find the version of the SDF file at the top of the file.

John
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#### anhtuan

##### Member level 4
sdf error

Yeah, my SDF file is 2.1 version.
But what can i do to solve the problem? Should i:
-Ignore the error (if this error is not important)
-Or find a different version of library cell (if this error is important)
Could you suggest me a solution?
Thank you very much!

#### dft_guy

failed to find hold timingcheck

You should probably take a look a the library, and see if it has a $recrem timing check specified (recrem = RECoveryREMoval). if so, most likely it supports sdf 3.0, and the best course of action is to try to output the sdf in 3.0 format. It may also be that the library spports both, but requires a compile-time switch to conform to one or the other. if there is no$recovery OR \$recrem in the specify block, then just ignore it. But that's the last resort. The synthesis library and simulation library should not be that far off..

John

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#### kiranks9

##### Member level 3
+sdf +error

when u r compiling the library cells, u can use the options like timing check for simulation perpose afterwords check back annotation happen properly or not

#### chipmonkey

##### Member level 2
Re: SDF error

@anhtuan: were you able to solve this issue.. im also facing the exact same issue:sad:

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