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AR# 10278

7.1i XC9500 CPLDFit - The fitter report incorrectly shows outputs as I/Os

Description

General Description: 

I created a design with inputs and outputs, but no bidirectional ports. After fitting, the fitter report shows bidirectional I/Os for some signals that should be outputs only.

Solution

Check your fitter options. It is likely that "Pin Feedback" is enabled. This means that the software is allowed to use an output as a bidirectional signal in order to feed the output back into the device to be used by other logic (i.e., a bidirectional signal). If you do not want this, disable "Pin Feedback" in the fitter options and re-implement your design.

AR# 10278
Date Created 08/29/2007
Last Updated 05/07/2014
Status Archive
Type General Article