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# 34810

11.x Implementation - Can instantiated but unused IOB primitives be removed from a netlist?

Description

I have a encrypted netlist which contains instantiated input/output primitives for signals I will not use in the design. When I run through the ISE tools, the unused signals are then brought up to the top level of my design. Is there any way to prevent this from happening and have the unused signals removed by the ISE tool?

Solution

Pads will be inferred by the implementation tools if there are I/O bufferprimitives (IBUF, OBUF, OBUFT, etc.) in the logical netlist. To prevent the implementation tools from instantiating pads, the I/O buffer primitives need to be removed.

Contact the 3rd party provider of the encrypted netlist to check whether they can provide a netlist without I/O buffers. Typically, this can be done by turning off the "Add I/O Buffers" property for XST (Refer to Xilinx Answer 34771). 3rd party synthesizers have similar switches, which can be found in their documentation.

Linked Answer Records

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
34771 10.1/11.x NGDBuild - "ERROR:NgdBuild:770..." N/A N/A
AR# 34810
Date Created 03/17/2010
Last Updated 12/15/2012
Status Active
Type General Article
Tools
  • ISE Design Suite - 11.1
  • ISE Design Suite - 11.2
  • ISE Design Suite - 11.3
  • More
  • ISE Design Suite - 11.4
  • ISE Design Suite - 11.5
  • Less