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216 Views
Registered: ‎05-26-2019

Timing constraints editor on implementation duplicates constraints in XDC file

Hi all,

 

I am learning FPGA design. I have small design with 2 RAM instances of RAM IP generated modules, a multiplier and some LEDs, Switches in circuit.

 

After synthesis & implementation, I try to create a new constraints file with custom IO planning and timing constraints. I can successfully place IO Ports Pin maps, but when it comes to timing maps, when I add a set_maximum_delay constraint, the constraint editor creates multiple duplicates after re-running implementation with new constraint file. Any suggestions would be greatly appreciated. Thank you.

 

Vivado Version: 2018.2 (SW build 2258646)

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Xilinx Employee
Xilinx Employee
166 Views
Registered: ‎07-16-2008

回复: Timing constraints editor on implementation duplicates constraints in XDC file

Would you please elaborate on "the constraint editor creates multiple duplicates"? 

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159 Views
Registered: ‎05-26-2019

回复: Timing constraints editor on implementation duplicates constraints in XDC file

So When after initial IO planning, I go on to create clocks and set inpt and output delays. At this point,the implementation results look normal.
1. Then I add multi-cycle path and false path constraints and the implementation results and XDC file looks as expected. But when I add maximum_delay timing constraint, suddenly I see multiple duplicates in the XDC file after running through implementation. And whenever I edit any maximum_delay constraints in timing editor and run implementation, then it make a duplicate of the already previously duplicated constraint.

If I try to remove these constraints by hand, it doesn't work.
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Xilinx Employee
Xilinx Employee
147 Views
Registered: ‎07-16-2008

回复: Timing constraints editor on implementation duplicates constraints in XDC file

If you add set_max_delay constraint via Constraint Editor, it's saved in memory and not written to target XDC until you save the design. Do you mean you observe multiple lines of the same set_max_delay constraint after you save to XDC?

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