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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>The intent behind SDIO is to allow the use of an SD slot for more than

memory cards. SDIO allows I/O devices such as GPS, camera, Wi-Fi, FM radio,

Ethernet, barcode readers and Bluetooth to be plugged into such a slot. </p>

<p>However, with space being limited in modern mobile phones, memory card

slots are usually microSD slots - which are too small to accept SDIO or miniSDIO

cards. Also, memory card slots are often internal to the phone which prohibits the

insertion of SDIO cards. Therefore in Symbian devices, SDIO is typically used

only as an internal peripheral bus on all but hardware reference platforms.

Because of its ability to provide high-speed data I/O with low power consumption,

SDIO can be used to connect components such as Wi-Fi and FM radio peripheral

chips to the main processor.</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_d0e99133_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 described below.</p><ul>

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

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

write operations</p></li>

</ul><ul>

<li><p><i>SDIO Host controller</i> 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><i>General Card Functions</i> 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 Class 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><p>This

API is used by the implementers of the class drivers.</p><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 outstanding requests simultaneously.

 It schedules these requests onto the bus, thereby putting the appropriate

card into 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

an I/O function object provided through the <codeph>IOFunction()</codeph>,

which 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 APIs that are used most frequently

during the implementation of the SDIO class 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>