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AR# 57808

Vivado Constraints - Order dependency of -THROUGH switch

Description

In the below schematic, if I want to constrain the path between FDRE_inst1 and FDRE_inst4 using the FROM THROUGH TO constraint, do I have to specify the THROUGH elements in order?
 
cap.png



Solution

Yes, the elements mentioned for the -THROUGH switch should be written in order.
 
In the above example the following constraint is valid:

 

set_multicycle_path 2 -from [get_pins FDRE_inst1/C] -to [get_pins FDRE_inst4/D] -through [get_cells LUT1_inst2] -through [get_cells LUT1_inst3]

However, the following constraint is invalid and the tool will not identify the path.

set_multicycle_path 2 -from [get_pins FDRE_inst1/C] -to [get_pins FDRE_inst4/D] -through [get_cells LUT1_inst3] -through [get_cells LUT1_inst2]

AR# 57808
Date Created 10/04/2013
Last Updated 12/16/2014
Status Active
Type General Article
Devices
  • FPGA Device Families
Tools
  • Vivado Design Suite - 2013.2
  • Vivado Design Suite - 2013.3
  • Vivado Design Suite - 2013.4
  • More
  • Vivado Design Suite - 2014.1
  • Vivado Design Suite - 2014.2
  • Vivado Design Suite - 2014.3
  • Less