Programmable Devices
CPLDs, FPGAs, SoC FPGAs, Configuration, and Transceivers
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19974 Discussions

Bidirectional Pins and inout

Honored Contributor II

I'm trying to understand how to use bidirectional pins and inout. Simple put I have a verilog code that looks like this 


input oe; 

input a; 

output ab; 

inout b; 


assign b = (oe) ? a : 1'bz: 

assign ab = b 


The intended operation is that 'ab' will get what is on the pad 'ab' either 'a' or what is driving 'ab' when tri-stated. 


The seconds part is the top level is a schematic (.bdf). I have used a 'BIDIR' pin connected to the 'ab' and get a compiler warning that the pin tristate that pin 


What am I missing or NOT see? 


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