UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 52440

Vivado Constraints - What is the difference between -combinational and -divide_by when using create_generated_clock?

Description

The Vivado Tcl Reference Guide includes the following on page 140:

"-combinational - (Optional) Define a combinational path to create a "-divide_by 1" generated clock"

Why would I need a new switch when this can be done already using the -divide_by {1} switch?

What is the scenario in which I would use this combinational switch?

Solution

-combinational:

The source latency paths for this type of generated clock only include the logic where the master clock propagates.

The source latency paths do not flow through sequential element clock pins, transparent latch data pins, or source pins of other generated clocks.

This option is not intended to be used with logic that manipulates the clock, such as CMB (Clock Modifying Block).

-divide_by:

-divide_by arg - (Optional) Divide the period of the master clock by the specified value to establish the period of the generated clock object.

AR# 52440
Date 08/08/2017
Status Active
Type General Article
Tools
  • Vivado Design Suite
Page Bookmarked