Forum Discussion
Occasional ContributorAbout loading constraints
The constraints you used will remove the Unconstrained path being reported out because the -to node (RLO_CLK_node) that is false path is the same.
At the end, designers need to know their design requirement and know where & when to use set_false_path. These constraints tell Timing Analyzer not to analyze specific paths or clock transfers. Once a path has been cut by either of these commands, there is no way to un-cut it, i.e. these constraints have the highest priority.
Regards,
Richard Tan
Super ContributorIt seems that the path is Invalid in the Report Exception. Invalid means that: No paths are affected by this exception. This occurs when a timing exception has valid -from, -to, or -through collections, but there are no actual paths from the -from nodes to the -to nodes.
You can use the wildcard again to fix that.
set_false_path -from [get_pins {s_rlo_clk_cnt|*}] -to [get_ports {RLO_CLK_NODE}]
You can also use the following false path to removes this port from showing up in the Unconstrained Path:
set_false_path -to [get_ports {RLO_CLK_NODE}]
Regards,
Richard Tan
Yamada1Thank you for answering.
We have confirmed that this can be avoided by using a wildcard for the target as in the case of input ports.
I tried it and realized that I was able to avoid this by changing line 17 of the SDC file as shown below, but is this correct?
set_false_path -from [get_pins {s_rlo_clk_cnt|clk}] -to [get_ports {RLO_CLK_NODE}]
We apologize for the inconvenience and appreciate your understanding.
