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<concept id="GUID-7D535B68-CA7F-4796-80FB-AE7A27642A88" xml:lang="en"><title>SDIO

Overview</title><shortdesc>SDIO is an Input/Output interface based on the SD card standard. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>SDIO is an I/O interface based on the SD card standard. SDIO cards are

used to fill a growing demand for multimedia content. It is an interface that

extends the functionality of devices with an SD card slot. This kind of combination

is usually found in devices that can be ported easily and make heavy demands

on memory.</p>

<section id="GUID-82B34422-2F2D-4D1E-860A-556FEB7FF41B"><title>Required background</title><p>You

must have an understanding of SD card before using SDIO. </p></section>

<section id="GUID-D5194E78-3B55-40C9-A832-7E24C2CC43D3">       <title>Architecture</title><fig id="GUID-00983E3C-72BE-40EC-9F93-216741F00CD6">

<title>SDIO Architecture</title>

<image href="GUID-A819DE06-7B00-4643-9D3E-EFE14132981C_d0e318193_href.png" placement="inline"/>

</fig>           </section>

<section id="GUID-CF3292E0-0BF4-4FC2-9253-D052AF89AC1E"><title>Description</title><p>The

SDIO is divided into key modules as shown in the diagram above and described

below.</p><ul>

<li><p>Memory card performs the SD or the MMC card operations. It registers

the card driver, initialize the card, and sets permissions for the read and

write operations</p></li>

</ul><ul>

<li><p>SDIO Host controller is the most important module in the SDIO architecture.

It has a driver that allows card initialization, bus width settings, clock

frequency setting, sending and receiving of commands and SDIO interrupt handling.</p></li>

</ul><ul>

<li><p>General Card Functions module contains functions that are useful during

the development of other card drivers. The module supplies the read/write

SDIO/SD/MMC card register operations as well as select/deselect card, read

card status and reset card procedures.</p></li>

</ul></section>

<section id="GUID-19CA14BB-BE60-4063-BB68-E960357D2C96"><title>Key Concepts</title><ul>

<li><p><b>SDIO Interrupts:</b> SDIO Interrupts are level-sensitive interrupts.

They communicate with the host through the SDIO line.  The signal is held

active until the host acknowledges the interrupt through some function unique

I/O operation.</p></li>

</ul><ul>

<li><p><b>SDIO Driver:</b> SDIO Driver supports the SDIO Host Controller.

The driver includes functions such as initialization, bus settings, clock

frequency setting, sending and receiving of commands, and SDIO interrupt handling.</p></li>

</ul><ul>

<li><p><b>SDIO card controller:</b> SDIO card protocol is a super-set of the

SD card protocol. The SDIO Card Controller shares some of its functionality

with the SD controller. The Symbian platform SDIO card controller is implemented

as a set of SDIO card classes, each of which is derived from the corresponding

SD card classes. The SDIO card controller provides support for SDIO cards

within the E32 kernel. It manages access to the SDIO card hardware interface

and provides an API for class drivers to access SDIO card functions. </p> </li>

</ul></section>

<section id="GUID-069B6CC3-9811-4BD8-869E-596BC1C0313F"><title>API summary</title><table id="GUID-B0DC509E-F1BC-450F-9BBE-C3FFF85AEB06">

<tgroup cols="2"><colspec colname="col1"/><colspec colname="col2"/>

<thead>

<row>

<entry valign="top"><p>API names </p></entry>

<entry valign="top"><p>Description</p></entry>

</row>

</thead>

<tbody>

<row>

<entry><p><xref href="GUID-F84A87F1-7DDD-37D7-A936-EB5DEC4F4740.dita"><apiname>DSDIOSTACK</apiname></xref></p></entry>

<entry><p>The stack can handle multiple requests outstanding simultaneously.

 It schedules these requests onto the bus, there by putting the appropriate

card in transfer state automatically and running the appropriate state machine

function. </p></entry>

</row>

<row>

<entry><p><xref href="GUID-8E2210D1-CCE7-34B3-9D19-B7F79481CD67.dita"><apiname>TSDIOCARD</apiname></xref></p></entry>

<entry><p>This class owns the I/O function objects. It provides access to

the appropriate I/O function object that is provided through the IOFunction()

that returns a pointer to the object concerned. </p></entry>

</row>

<row>

<entry><p><xref href="GUID-87D13F47-6680-34DD-956E-AB2A8C21AE19.dita"><apiname>DSDIOSESSION</apiname></xref></p></entry>

<entry><p>This contains functions for setting up a session object to perform

SDIO specific command sequences such as initialization, scheduling, invoking

and submitting the session.</p></entry>

</row>

<row>

<entry><p><xref href="GUID-522BF42B-1A3F-3FF7-B227-39AC1A285C10.dita"><apiname>DSDIOREGINTERFACE</apiname></xref></p></entry>

<entry><p>This contains the API that are used most frequently during the implementation

of the SDIO drivers. It contains member functions that allow single byte read

or write operations to a given register address together with the corresponding

ones for multi-byte access</p></entry>

</row>

<row>

<entry><p><xref href="GUID-7CC8E73B-0656-3ABD-AA70-6C309E74C035.dita"><apiname>TSDIOFUNCTION</apiname></xref></p></entry>

<entry><p>This contains member functions for access and control of function

specific features such as function enable, function ready. It also has the

member functions for access and control of FBR features such as CSA access

and function block size. </p></entry>

</row>

<row>

<entry><p><xref href="GUID-0CABFFC3-743C-35EB-99E0-1B0452E4A42B.dita"><apiname>TSDIOINTERRUPT</apiname></xref></p></entry>

<entry><p>This contains the usual interrupt object member functions It provides

the abstraction of a per-function interrupt even though each function actually

shares a single interrupt request signal on the card. </p></entry>

</row>

</tbody>

</tgroup>

</table></section>

</conbody></concept>