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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-BDF1F32B-796B-4D3D-9C91-43FF8E9DDAF9" xml:lang="en"><title>SDIO
Commands Tutorial</title><shortdesc>Lists commands to the SD bus that are specific to SDIO.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The SDIO hardware interface extends the functionality of SD devices. The
combination of SD card with I/O is usually found in devices that can be ported
easily and make heavy demands on memory. </p>
<table id="GUID-0DC73E53-1A1E-4849-8166-D5FACA2377BE"><title>SDIO Hardware
Interface</title>
<tgroup cols="3"><colspec colname="col1" colwidth="0.66*"/><colspec colname="col2" colwidth="0.67*"/><colspec colname="col3" colwidth="1.67*"/>
<thead>
<row>
<entry valign="top">Supported SDIO Command</entry>
<entry valign="top">Interface functions</entry>
<entry valign="top">Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><p>CMD5</p></entry>
<entry><p><codeph>IO_OP_COND</codeph></p></entry>
<entry><p>Used during initialization to determine the presence of an SDIO
card and set the voltage.</p></entry>
</row>
<row>
<entry><p>CMD52</p></entry>
<entry><p><codeph>IO_RW_DIRECT</codeph></p></entry>
<entry><p>Used to address and access a single register.</p></entry>
</row>
<row>
<entry><p>CMD53</p></entry>
<entry><p><codeph>IO_RW_EXTENDED</codeph></p></entry>
<entry><p>Used to address multiple registers with a single SDIO command. This
is called by the <codeph>IssueMMCCardCommand()</codeph> function.</p></entry>
</row>
<row>
<entry><p>R4</p></entry>
<entry><p><codeph>IO_SEND_OP_COND</codeph></p></entry>
<entry><p>The SDIO response. <xref href="GUID-908B4DA8-8E1C-3B38-90FF-14EC52277B91.dita#GUID-908B4DA8-8E1C-3B38-90FF-14EC52277B91/GUID-FFD5A33A-73D2-3D19-94EF-638049B8B6E7"><apiname>DSDIOStack::ExtractSendOpCondResponse(aResponse,aFunctionCount)</apiname></xref> is
used to extract the SDIO operation response.)</p></entry>
</row>
<row>
<entry><p>R5</p></entry>
<entry><p><codeph>IO_RW_DIRECT</codeph></p></entry>
<entry><p>The SDIO response, handled by TSDIORseponseR5. It also provides
information about the current state of the SDIO bus, error state, and the
byte order the data is read.</p></entry>
</row>
</tbody>
</tgroup>
</table></conbody><related-links>
<link href="GUID-9BBDFF77-5E2C-4E13-BEB3-716CC80B3375.dita"><linktext>SDIO Implementation
Overview</linktext></link>
</related-links></concept>