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<concept id="GUID-0E5A241A-19F5-5754-B454-45747A8D80E1" xml:lang="en"><title>SD Card

Overview</title><shortdesc>Description of SD card features available to application developers

and what a device creator must write to provide SD card support.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>SD memory cards (Secure Digital memory cards) are flash-based memory cards

designed to provide secure high capacity data storage. </p>

<p>The SD controller supports the <i>Simplified SD Physical layer specification

version 2.0</i> which is owned by the <i>SD Card Association</i> and the <i>SD

Group</i>. </p>

<p>The SD memory card standard is defined to be protocol forward compatible

with MultiMediaCard version 2.11 and it is possible for a MultiMediaCard to

be inserted into an SD memory card socket and host systems to support both

types of card. </p>

<section id="GUID-DDA73F0B-1F92-4A2E-A243-BD595BD1AB5F"><title>Purpose</title> <p>SD

cards are based on MultiMediaCards (MMC) but with additional functionality

detailed below. Symbian platform support for SD is built on top of the MMC

support. This section describes the additional functionality available to

applications using SD cards. This section also describes the additional work

required to support SD cards. </p> </section>

<section id="GUID-3C8A4D9E-52A4-4DDD-B831-09530C5D3927"><title>Required background</title> <p>You

should be familiar with the following: </p> <ul>

<li id="GUID-390334A3-BC5D-5E90-A114-E44C724DE63B"><p><xref href="GUID-79B2CF91-FB95-5E7C-81CC-235A6A660D88.dita">MMC

Controller</xref>  </p> </li>

<li id="GUID-C1841C2F-9D08-59D4-8183-6B1179D33763"><p> <xref href="http://www.sdcard.org/developers/tech/sdcard/pls/" scope="external">SD Simplified Specification</xref>  </p> </li>

</ul> </section>

<section id="GUID-3078C10F-852B-4B2A-A645-53B83E3A9601"><title>Key concepts

and terms</title> <p>An SD card is very similar to a MultiMediaCard (MMC)

but with additional features to support high capacity, high speed, secure

storage. </p> <p>As SD cards are very similar to MMC, you should read the

section on <xref href="GUID-BE6AFD38-5952-537F-848C-C76C8F5FA9BF.dita">MMC Controller

Architecture</xref> before reading the <xref href="GUID-114A23CF-BF8B-54F5-8AF6-FEF007891884.dita">SD

Controller</xref> documentation. </p> </section>

<section id="GUID-F62ED0EA-EC26-4BA9-8916-48CF9540F4A5"><title>Architecture</title> <p>SD

support is divided into two parts, the Platform Independent Layer (PIL) and

the Platform Specific Layer (PSL). </p> <p>The PIL is implemented as an E32

peripheral bus controller - <filepath>EPBUSSD.DLL</filepath> which is a kernel

extension and extends the functionality of the matching MMC library <filepath>EPBUSM.DLL</filepath>.

The <filepath>EPBUSSD.DLL</filepath> library consists of a generic peripheral

bus layer, which is identical to the one used for MMC, and a generic SD card

layer. The SD card layer is a superset of the MMC layer and derives additional

classes for SD cards from the MMC classes. These derived classes support the

additional features found in an SD card. </p> <p>The additional functionality

available in an SD card includes: </p> <ul>

<li id="GUID-832D06C4-3EA0-552B-8002-3CB9CB281BE7"><p>an optional 4-bit wide

data bus </p> </li>

<li id="GUID-04D41D5C-B0E4-51FE-96D8-561EADE20D11"><p>individual SD card addressing </p> </li>

<li id="GUID-B1EA016E-F935-5590-9446-86B0C4825B51"><p>support for card capacities

of 4Gb and above </p> </li>

<li id="GUID-741CF2BF-08A3-50C1-B3B8-DF616C9C5B28"><p>revised erase ranges

allowing smaller ranges to be erased from an SD card </p> </li>

<li id="GUID-BCEA1C92-84C5-5571-9AE0-BA7AC76B3003"><p>optional secure data

area for DRM - the Symbian platform does not provide support for using the

secure data area on an SD card. </p> </li>

</ul> <p>You, as a device creator, will need to write the PSL. Implementing

the PSL is described in <xref href="GUID-E194A923-99E7-5DC1-BB78-D050A4793A60.dita">SD

Controller PSL Implementation</xref>. </p> </section>

<section id="GUID-E171D6A0-8E46-4356-A41D-D76E866D8AFD"><title>Key Classes</title> <p>The

classes used for SD cards are SD specific versions of the classes used for

the MMC cards and the main SD-related are listed here. </p> <table id="GUID-42E860FB-DF1F-5F11-93EA-DAF25C892B9D">

<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

<thead>

<row>

<entry>Class</entry>

<entry>Description</entry>

</row>

</thead>

<tbody>

<row>

<entry><p> <xref href="GUID-3DC34D4F-E693-3BF0-B5D6-DF22FCE37340.dita"><apiname>DSDStack</apiname></xref>  </p> </entry>

<entry><p>The stack of memory cards, derived from <xref href="GUID-B5193656-9819-3E00-A335-EEF1726115A5.dita"><apiname>DMMCStack</apiname></xref>.

Uses the star topography to identify each SD card rather than the bus topography

used by MMC. Also handles individual card initialization. </p> </entry>

</row>

<row>

<entry><p> <xref href="GUID-B170A819-C146-3DD2-85C2-69CC121A9023.dita"><apiname>TSDCard</apiname></xref>  </p> </entry>

<entry><p>Derived from <xref href="GUID-5B985623-6A0B-3FBB-90BD-367F25CC70E7.dita"><apiname>TMMCard</apiname></xref> but contains the erase sector

size and any special formatting requirements for the SD card. Includes information

from the SCR. </p> </entry>

</row>

</tbody>

</tgroup>

</table> </section>

<section id="GUID-F307971E-537A-44C8-8D52-41C762A3C347"><title>Typical uses</title> <p>The

typical uses for the SD card classes are the same as for MMC. </p> </section>

</conbody><related-links>

<link href="GUID-79B2CF91-FB95-5E7C-81CC-235A6A660D88.dita"><linktext>MMC Controller</linktext>

</link>

<link href="GUID-058BAEDF-5E04-5BB4-928F-0E0528FD9465.dita"><linktext>MultiMediaCard

Technology</linktext></link>

<link href="GUID-BE6AFD38-5952-537F-848C-C76C8F5FA9BF.dita"><linktext>MMC Controller

Architecture</linktext></link>

<link href="GUID-C059F39F-BC53-5C92-B05E-863B8CF22859.dita"><linktext>Command Objects</linktext>

</link>

</related-links></concept>