Description

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General Description: 

I am trying to perform a functional simulation of the core generated by ModelSim, but it does not work, as the outputs are always undefined.  

However, using a post-route simulation, the core works as expected.

Solution

To perform a functional simulation in ModelSim, the testbench configuration statement must be altered so that it has the following format: 

CONFIGURATION <testbench_cfg> OF <testbench_name> IS 

FOR <testbench_arch> 

for all : <design_name> use configuration work.<design_name_cfg>; 

end for; 

END FOR; 

END <testbench_cfg>; 

- In ModelSim, compile the <my_design.vhd> file and the <tesbench.vhd> file. 

- Then, load the <testbench_cfg> file. 

- Add the entity to the waveform window, and run the simulation. 

This will allow the functional simulation to operate correctly. 

In order to perform a post-route simulation, the testbench configuration statement needs to be altered so that it has the following format: 

CONFIGURATION <testbench_cfg> OF <testbench_name> IS 

FOR <testbench_arch> 

END FOR; 

END <testbench_cfg>; 

- In ModelSim, compile the <time_sim.vhd> file and the <tesbench.vhd> file. 

- Then, load the <testbench> file. 

- Add the entity to the waveform window, and run the simulation. 

This will allow the post-route simulation to operate correctly.