how to write inverted clock signal in ucf?

Question

Like - create_generated_clock [get_pins xyz] -source clk -divide_by 4 -invert

I need to convert sdc to ucf .

How to write -invert in UCF constraint ?

Answer 1

A inverted clock clock_n <= not clock is equal to a clock with a phase shift of 180 degree assuming a duty cycle of 50/50 percent.

But why are you describing this clock manually? It looks like a clock from a PLL, DCM or MMCM. These generated clocks are automatically derived from CLKIN* of the clock modifying block (CMB in xdc terms) in both cases: UCF and XDC.

UG612 describes UCF timing constraints. Have a look to pages 27 to 32: http://www.xilinx.com/support/documentation/sw_manuals/xilinx11/ug612.pdf