Intel® Quartus® Prime Software
Intel® Quartus® Prime Design Software, Design Entry, Synthesis, Simulation, Verification, Timing Analysis, System Design (Platform Designer, formerly Qsys)
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2 FFs synchronizer constraint

Altera_Forum
Honored Contributor II
‎03-17-2013 01:49 PM
1,415 Views

Hi, 

I am using a 2 FFs synchronizer in my design, and it requires a constraint that tells quartus to place the 2 FFs as close as possible to each other. 

how do i set this constraint? is it in the sdc file? what is the syntax? 

 

Thanks. 

 

G.
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Altera_Forum
Honored Contributor II
‎03-17-2013 02:33 PM
634 Views

set_max_delay -from FF1 -to FF2 1.0 

That puts a 1ns constraint on it. That's quick and easy. Note that TQ has metastability analysis tools, whereby you can get it to recognize synchronizers. The fitter then automatically puts them close together, and will calculate an MTBF for each synchronizer and the whole design. This takes more work though, which is why most people do the first.
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Altera_Forum
Honored Contributor II
‎03-18-2013 10:38 AM
634 Views

how do i set the TQ to recognize synchronizers? i didn't find it.

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Altera_Forum
Honored Contributor II
‎03-18-2013 01:18 PM
634 Views

Search on metastability and it should come up: 

http://www.altera.com/literature/hb/qts/qts_qii51018.pdf
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