I've developed some IP using Xilinx ISE, and this required settings some multi-cycle path constraints in the UCF file:

NET "lowlat_result<0>" TPTHRU = "through_lowlat_result";
# ....
NET "clk" TNM_NET = clk;
TIMESPEC TS_clk = PERIOD "clk" 125 MHz HIGH 50%;
TIMESPEC TS_multipath_factll_result = FROM "FFS" THRU "through_lowlat_result" TO "FFS" TS_clk / 20;

I want to now utilize this VHDL code in a Xilinx Platform Studio (EDK 13.2) custom peripheral. There is no generated UCF file for the peripheral itself. Can I add one?

Or, do my constraints need to go in the main data/system.ucf file? I'm not sure of how the scoping works for net names in entities many layers deep.


2 Answers 2


This question has been solved in this link [http://forums.xilinx.com/t5/Embedded-Development-Tools/Specify-user-constraints-UCF-for-Xilinx-Platform-Studio-custom/td-p/344231]

  • \$\begingroup\$ Thanks for posting that link to my question on the Xilinx forums -- I'd forgotten that I'd asked on both sites. Link-only answers aren't particularly good on SE sites however, so I added an answer quoting the answer from Xilinx. \$\endgroup\$ Feb 26, 2017 at 20:23

I asked this question on the Xilinx Community Forums, where it was answered:

You can include the user constraints in the system.ucf available at $EDK_Project/data folder.


  1. Use EDK/XPS to generate bitstream (Hardware --> Generate Bitstream).
  2. Terminate the flow at ngdbuild(Step1 of snapshot)
  3. Launch constraints_editor to source system.ngd($EDK_Project/implementation folder) and system.ucf ($EDK_Project/data folder) [Step2 and Step3]
  4. Apply constraints based off this link. http://www.xilinx.com/support/documentation/sw_manuals/xilinx13_1/pce_c_overview.htm

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