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AR# 44918

Vivado Constraints - UCF versus XDC (SDC)


What are the differences between UCF and XDC constraints/commands?


There are many differences between UCF constraints and XDC commands. Below are a list of some of these differences:

  • UCF constraints are defining the internal delays of the FPGA, but XDC commands are defining the internal and external relationships between the clock and the upstream/downstream devices for the I/Os
  • UCF constraints are timing group (TNM, TNM_NET, TIMEGRP) based, but the XDC commands are instance (get_cell), net (get_net), pin (get_pin), and port (get_port) based
  • UCF constraints define the requirements as a maximum delay, but XDC commands can define both the minimum and maximum delay for a given path


AR# 44918
Date 08/07/2013
Status Active
Type General Article
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