how to use a .ucf file?

[Marija]

Hello all, <p>I understand that I can assign <BR>
timing constraints using a .ucf <BR>
file. <p>I tried defining one (using the <BR>
wizard) and including it in the <BR>
project. In synthesis properties <BR>
it is not possible to point out <BR>
a .ucf file, and a .xcf file is <BR>
expected. I left this blank. I <BR>
selected the option 'write timing <BR>
constraints file' and run the <BR>
synthesis process. I see the tool <BR>
consulting the .ucf file and gives <BR>
no warnings. I ran Implement <BR>
design processes and have a <BR>
information that all of the timing <BR>
constraints are met. When I run <BR>
the simulation using <BR>
ModelSim, .sdf and .vhd file <BR>
generated by the ISE tool, the <BR>
results look like the timing <BR>
constraints are not met (even if I <BR>
select a frequency much smaller <BR>
than the tool accepted). <p>Hints? <p>Thanks in advance, <BR>
Marija

 

[Jim Wu]

ngdbuild should automatically pick up a ucf file if it is included in the
project. You can also try adding "-uc ucf_file_name" to the ngdbuild command
line.

I'd double check the clock frequency on the waveform. You clock generation
code may assume a time unit and only use a number as the period. This may
not work if the timing simulation uses a different time unit than the one
used in the functional simulation.

HTH,
Jim
jimwu88NOOOSPAM@yahoo.com
http://www.geocities.com/jimwu88/chips



"Marija" &lt;gemini@verat.net&gt; wrote in message
news:ee83aea.-1@WebX.sUN8CHnE...
Hello all,
I understand that I can assign
timing constraints using a .ucf
file.
I tried defining one (using the
wizard) and including it in the
project. In synthesis properties
it is not possible to point out
a .ucf file, and a .xcf file is
expected. I left this blank. I
selected the option 'write timing
constraints file' and run the
synthesis process. I see the tool
consulting the .ucf file and gives
no warnings. I ran Implement
design processes and have a
information that all of the timing
constraints are met. When I run
the simulation using
ModelSim, .sdf and .vhd file
generated by the ISE tool, the
results look like the timing
constraints are not met (even if I
select a frequency much smaller
than the tool accepted).
Hints?
Thanks in advance,
Marija