# Error: Identifier "ODDRE1" does not identify a component declaration.

#### Cesar0182

##### Member level 3
Greetings ... comment that I am trying to simulate a project made in Vivado 2017.3 and the simulator I am using is Modelsim SE 64 10.5, the error I have is the one shown in the attached image.

Initially the simulation worked correctly, but to this project I added a new IP created in ISE 14.5, which initially gave me the error:
therefore I decided to update it to the version of Vivado 2017.3, but even so I still had the same error, later I wanted to verify if the same thing happened in the Vivado simulator, but incredibly it worked without problems there. But still I ended up removing the IP from the project. And from there that my project began to show me that error that I share and so far I have not been able to find a solution to this.
Could someone help me with this please.

##### Super Moderator
Staff member
If this purely a simulation issue, wipe out the entire simulation directory. I normally run Modelsim with a scripts. I usually have two different scripts, one to compile vendor libraries and one to compile the design files, in either case the first couple of lines in the file checks for and deletes the libraries it compiles.

It seems to me you compiled the IP from ISE 14.5 and it overwrote or added something that is causing the problem.

As you indicate you ran the Vivado simulator without problems I'm assuming you use the Vivado GUI to launch your simulation, which automatically generates a Tcl script to compile and run the simulation, so the proper libraries are almost always correctly called out. BTW, I also write my own scripts to run Vivado simulation due to the Vivado generated script not supporting some of the testbench methodologies I use on a regular basis.

#### TrickyDicky

Your error indicates you didnt include a component for ODDRE1
ODDRE is part of the unisim library
Did you include the components library at the top of the file?

Code:
library unisim;
use unisim.vcomponents.all;

##### Super Moderator
Staff member
Your error indicates you didnt include a component for ODDRE1
ODDRE is part of the unisim library
Did you include the components library at the top of the file?

Code:
library unisim;
use unisim.vcomponents.all;
Thanks for pointing this out, I don't run VHDL simulations all that often so wasn't certain about the error message pointing to a missing library or component declaration.

If you decide to run vsim using the command line then the switch "-L unisim" needs to be added. The primitive libraries are added automatically when using the GUI to run simulations.