描述

The design has a top level ngc (top.ngc) and a lower level ngc called system.ngc and a system.ncf in the project folder. But, while implementing the design, the NCF seems to be taken into account.  

And, as a result of this, following error comes up. If I attempt to run translate again with no changes to the design, it fails with the following errors:
ERROR:NgdBuild:1197 - The constraint <TIMESPEC TS_system_i_clock_generator_0_clock_generator_0_DCM0_CLK_OUT_0_ = PERIOD "system_i_clock_generator_0_clock_generator_0_DCM0_CLK_OUT_0_" TS_sys_clk_pin  HIGH 50%> is overridden by the constraint <TIMESPEC TS_system_i_clock_generator_0_clock_generator_0_DCM0_CLK_OUT_0_ = PERIOD "system_i_clock_generator_0_clock_generator_0_DCM0_CLK_OUT_0_" TS_sys_clk_pin HIGH 50%>. Please set XIL_NGDBUILD_CONSTR_OVERRIDE_WARN to demote this message to a warning. 

How can we overcome this issue?

解决方案

There are two ways of working around this issue:- 

1. Try including -uc option instead of using -i option in the Ngdbuild. The "uc" option will make the tool parse UCF. 

ngdbuild -ise "ProjNav.ise" -intstyle ise -dd _ngo -nt timestamp -i -bm edkBmmFile.bmm -p xc3s200-ft256-4 top.ngc top.ngd  

2. The other option is to Open the ISE project and Recreate the Constraints Database. 

This issue is fixed in the next release of software.