post-PAR simulation problem

[thomasc]

post-PAR simulation problem

Hi,

I am doing a post-PAR simulation on ModelSim, which is launched by Xilinx
ISE 6.3 post-synthesis simulation. For some reason I don't understand, the
output waveforms are mostly red lines(unknowns) and the results are all
wrong. I guess it might be due to a timing problem but I couldn't figure
out how to fix it. I also heard that this kind of situation might occur
due to setup and hold time of the device I use(Xilinx Spartan-3 XC3S400).


Can anyone let me know why this happens and how o fix it?

Thank you!

 

[Neo]

have you taken into account the setup and hold times in your simulation
TB.

 

[soxmax]

thomasc wrote:

post-PAR simulation problem

Hi,

I am doing a post-PAR simulation on ModelSim, which is launched by Xilinx
ISE 6.3 post-synthesis simulation. For some reason I don't understand, the
output waveforms are mostly red lines(unknowns) and the results are all
wrong. I guess it might be due to a timing problem but I couldn't figure
out how to fix it. I also heard that this kind of situation might occur
due to setup and hold time of the device I use(Xilinx Spartan-3 XC3S400).


Can anyone let me know why this happens and how o fix it?

Thank you!

The red lines represent unknowns. Make sure you set or reset all of
your signals during initialization. You can use a make-believe reset
signal that comes from outside your project to accomplish this task.

Hope this helps
-Derek