XST design frequency setting

To learn the tool, just give ISE a known good synchronous hdl design file. It will tell you what Fmax is, and draw you an rtl schematic.

Then read the docs and the command files it made.

-- Mike Treseler

UCF file?

NET "clk" TNM_NET = "clk"; TIMESPEC "TS_clk" = PERIOD "clk" 0.025 us;

Hans

XST timing constraints are set up in the .xcf file

In the 9.2i XST user manual %xilinx%\doc\usenglish\books\docs\xst\xst.pdf

Look at: "XST Constraint File (XCF)", page 325 "XST timing options", page 336

The XST command line field is described in the first section listed above.

In the ISE GUI, you add this file to the flow by:

- right click on the "Synthesis - XST " line of the processes window, and select "Properties"

- in the "Synthesis Options" category: - set "Property Display Level" to "Advanced" - check the "Use Synthesis Constraints" button - fill in the "Synthesis Constraints File" field

If you want XST to forward annotate these to P&R tools, also check the "Write Timing Constraints" option.

Brian