AR# 40985

12.4/13.4.14.7 Pack - WARNING:Pack:1542: The register xxx has the property IOB=TRUE ...

Description

My design is getting the following warning message for an input Flip-Flop.

It was successfully packed into the input IOB.

Why is this warning message about an "output register" being printed?
 
 

WARNING:Pack:1542 - The register sharc/adsp_hbg_n_r has the property IOB=TRUE,
   but was not packed into the output side of an I/O component. The output
   register symbol "sharc/adsp_hbg_n_r" has loads outside the I/O component.
   The output register symbol "sharc/adsp_hbg_n_r" has loads outside the I/O
   component.

Solution

In this case, the Flip-Flop which is driven by an input buffer also has output buffer connectivity because it drives the 3-state enable pins of several OBUFTs.

Although the designer considered it to be an input Flip-Flop only, the tools also evaluated it for an output IOB pack.

That is why a warning message about the failed output IOB pack is printed despite the successful input IOB pack.
AR# 40985
Date 09/10/2014
Status Active
Type Error Message
Devices
Tools