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6,821 Views
Registered: ‎11-06-2015

UCF: tnm_net

Hi, I'm working with a Virtex-6 FPGA, so I have to use ISE. In the UCF Constraints Guide (UG625, http://www.xilinx.com/support/documentation/sw_manuals/xilinx14_7/cgd.pdf, page 194) it is said, that I can constrain a clock net directly without using a tnm_net: NET “net_name” PERIOD = period {HIGH|LOW} [high_or_low_time] INPUT_JITTER value; But there is also the warning/recommendation not to do this: "Caution! This is a secondary method, and is not recommended." Specifying a tnm_net is probably useful, when you have several nets you want to group, but if this is not the case, will there be any problems using this "secondary method"?
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Historian
Historian
6,805 Views
Registered: ‎01-23-2009

Re: UCF: tnm_net

Just don't do it...

 

This "secondary" method has probably been obsolete for more than a dozen years. No one ever uses it. As such there is always a higher likelihood to encounter an untested "feature" associated with this format...

 

Other than the one extra line of UCF code, there really isn't any disadvantage to defining the group...

 

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