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AR# 21718

NGDBuild 7.1i - Why do I receive "WARNING:NgdBuild:440 - FF primitive 'inst_name/BU118' has unconnected output pin"?

Description

General Description:

When I run NGDBuild on a design that contains certain CORE Generator IP ( Asynchronous FIFO, Synchronous FIFO and Block Memory), I receive many of the following warnings.

WARNING:NgdBuild:440 - FF primitive 'inst_name/BU118' has unconnected output pin

WARNING:NgdBuild:440 - FF primitive 'inst_name/BU261' has unconnected output pin

Why are these warnings occurring, and can I ignore them?

Solution

Many CORE Generator IP are parameterizable cores with many optional features. Although, these features might not be selected by the user, the netlist generated might still contain these unused ports. During MAP, these unused elements will be trimmed out, but during NGDBuild, these signals are still in the design and unconnected. Most of the core elements have instance names with BUxx, where xx is some number. These warnings can be safely ignored since these elements are unused in your parameterized core and the MAP tool will properly trim the unused elements.

AR# 21718
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article