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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-A5D862E4-3EC3-45C0-B635-23A02E5BB11F" xml:lang="en"><title>GPIO
Overview</title><shortdesc> General Purpose Input/Output (GPIO) allows easy serial expansion
of I/O through an interface.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>GPIO provides additional control and monitoring when the microcontroller
or chipset has insufficient I/O ports, or in systems where serial communication
and control from a remote location is advantageous. </p>
<section id="GUID-00227A5E-77BF-434F-B84F-880742E59151"><title>Required background</title><p>Before
beginning you should know the following:</p><ul>
<li><p>Understand platform implementation.</p></li>
<li><p>Understand GPIO concepts and terminology.</p></li>
<li><p>Know the architecture of the platform on which you are implementing.</p></li>
<li><p>Understand the functions you are implementing. </p></li>
</ul></section>
<section id="GUID-A4ECE25C-66A4-4161-9BD7-9FA431D5EE71"><title>Architecture
Description</title><p>There are two parts of a GPIO. They are the input path
and the output path.</p><ul>
<li><p><b>Input Path:</b></p> The input path is used to connect an external
signal to the internals of the microprocessor. This mode is generally used
for analog input and output to avoid oscillations in the internal digital
data bus when the signal level at the input is near the HIGH or LOW threshold. </li>
</ul><ul>
<li><p><b>Output Path:</b></p> The output path is used to bring external signals
from the internals of the microprocessor to the external world.</li>
</ul></section>
</conbody></concept>