Verilog Inout?

Question

What is inout in Verilog and how do I use it?

Answer 1

Inout is the type of a port connection to model a bidirectional port. Usually it is for tri-state bidirectional ports and is used in such a way:

inout sdata_io;

Let 'oe' be the output enable signal that enables the output to the stdata_io. Also it is valid to use a dedicated net for an internal use that is driven from that bidirectional port. So:

assign sdata_io = oe ? sdata_out : 1'bz; // if disable - high-impedance state (or will be drives the value of Z in other words).

This need to avoid conflicts at the bidirectional net:

assign sdata_in = sdata_io;

Also it will be valid if we add a pullup:

assign (pull1, pull0) sdata_io = 1'b1;

Answer 2

inout is a port type that is used when you want to use a signal both as an input and an output. But it is a wire and continious assignment must be used for it.