cells set to dont use in library

While trying to do PnR of a design, I see that the dont use attribute of 95% of the standard cells in the .lib file of the standard cell library are set to be true. Why they are included in the lib file if they are supposed to be set to dont use?? Can I change the dont use attribute and use the cells in my design?

Answer is YES. How would you do that depends on the tool.

Every mature PnR tool has option to set this attribute to false on list of cells. You'll have to refer to manual to find the syntax.

Has.
https://amzn.to/2tP6lBi

I know that setting the dont use attribute changes the usability of the cell. My question is why most of the cells are being set to don't use in the library? Can I make all those cells usable and use in the design? Or should I take care of something when I change the usability of the cell?

biju4u90 said:

I know that setting the dont use attribute changes the usability of the cell. My question is why most of the cells are being set to don't use in the library? Can I make all those cells usable and use in the design? Or should I take care of something when I change the usability of the cell?

Click to expand...

Change dont_use attribute to "FALSE", then you can use those cells.
Before doing so, confirm with library vendor whether it is OK or not.

slutarius said:

Before doing so, confirm with library vendor whether it is OK or not.

Click to expand...

That is my question too. Can we set the attribute to FALSE without the vendor permission and use those cells? Is it the vendor who should say whether it is OK? If it is not OK, it will be just like a library without those unusable cells. Why should the vendors add unusable cells in the library?

biju4u90 said:

That is my question too. Can we set the attribute to FALSE without the vendor permission and use those cells? Is it the vendor who should say whether it is OK? If it is not OK, it will be just like a library without those unusable cells. Why should the vendors add unusable cells in the library?

Click to expand...

The dont_use attribute library can be from:
- Library vendor. You can ask Library Vendor/designer if it is from the library itself.
- Tool behavior. You can ask Tool vendor if the Tool add that atribute automaticall to the library.

Making the decision not to use a cell in a library depended on:
- Library vendor who has the experience on characteristic failure after fabrication result.
- Your design has different conditions than library's range. This can cause function failure or fab failure.

So, you need to confirm with library vendor before making the decision to use the cells.

I hope you can clarify your problem clearly before having the solution.

slutarius said:

The dont_use attribute library can be from:
- Tool behavior. You can ask Tool vendor if the Tool add that atribute automaticall to the library.

Click to expand...

I don't think the tool adds the attribute automatically, because when I open the .lib file as a text file, I can see most of the cells to be set as don't use.
What I don't understand is that why the library vendors provide unusable cells in the library!! To be precise, in my library, 95% of the cells are set to be don't use!! If they are not supposed to be used, why do they give them in the library?

biju4u90 said:

I don't think the tool adds the attribute automatically, because when I open the .lib file as a text file, I can see most of the cells to be set as don't use.
What I don't understand is that why the library vendors provide unusable cells in the library!! To be precise, in my library, 95% of the cells are set to be don't use!! If they are not supposed to be used, why do they give them in the library?

Click to expand...

Then, ask your library vendor.