List of Nodes for the -through Option - 2022.1 English - UG903

Vivado Design Suite User Guide: Using Constraints (UG903)
Document ID
UG903
Release Date
2022-06-01
Version
2022.1 English
  • The list of nodes for the -through option should be a list of valid pins, ports, or nets.
  • Multiple elements can be provided.

By default, the timing engine includes the clock skew inside the slack computation.

The -datapath_only option can be used to remove the clock skew from the slack computation. The -datapath_only option is supported only by the set_max_delay command, and requires the -from option.

The following table summarizes the impact of -datapath_only in the behavior of set_max_delay constraint.

The common behavior for the path delay calculation of set_max_delay with or without -datapath_only is:

  • Input delay is included in the path delay calculation when the path starts on an input port and that a set_input_delay has been specified on the port
  • Output delay is included in the path delay calculation when the path ends on an output port and that a set_output_delay has been specified on the port
  • The data pin setup time is included in the path delay calculation when the path ends on the data pin of a sequential element.
Table 1. Differences Between Max Delay Constraint With and Without -datapath_only
set_max_delay set_max_delay -datapath_only
Path delay calculation Skew included when the constraint starts on the clock pin of a sequential element or ends on the data pin of a sequential element. Skew never included.
Hold Requirement Untouched False-ed path
-from Option Optional Mandatory