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    10 <!DOCTYPE concept

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

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

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

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

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

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

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

    19 Group</i>. </p>

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

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

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

    23 types of card. </p>

    24 <section id="GUID-AA07DD5E-0DB7-4B0C-8475-7A36E9F600CA"><title>Purpose</title> <p>SD cards are based on MultiMediaCards (MMC)

    25 but with additional functionality detailed below. Symbian platform support

    26 for SD is built on top of the MMC support. This section describes the additional

    27 functionality available to applications using SD cards. This section also

    28 describes the additional work required to support SD cards. </p> </section>

    29 <section id="GUID-E53DD689-D81A-44A1-870B-3ECE796B86F1"><title>Required background</title> <p>You should be familiar with

    30 the following: </p> <ul>

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

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

    33 <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>

    34 </ul> </section>

    35 <section id="GUID-EC87FA96-C124-43A0-A173-510B8A73FE98"><title>Key concepts and terms</title> <p>An SD card is very similar

    36 to a MultiMediaCard (MMC) but with additional features to support high capacity,

    37 high speed, secure storage. </p> <p>As SD cards are very similar to MMC, you

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

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

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

    41 <section id="GUID-C800CBB8-057F-494B-B0B8-95C6DBE13006"><title>Architecture</title> <p>SD support is divided into two parts,

    42 the Platform Independent Layer (PIL) and the Platform Specific Layer (PSL). </p> <p>The

    43 PIL is implemented as an E32 peripheral bus controller - <filepath>EPBUSSD.DLL</filepath> which

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

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

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

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

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

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

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

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

    52 data bus </p> </li>

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

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

    55 up to 32Gb </p> </li>

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

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

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

    59 area - Symbian Platform does not provide support for using the secure data

    60 area on an SD card. </p> </li>

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

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

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

    64 <section id="GUID-D43830D1-D78F-48A7-8467-4E8A52FE403B"><title>Key Classes</title> <p>The classes used for SD cards are SD

    65 specific versions of the classes used for the MMC cards and the main SD-related

    66 are listed here. </p> <table id="GUID-42E860FB-DF1F-5F11-93EA-DAF25C892B9D">

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

    68 <thead>

    69 <row>

    70 <entry>Class</entry>

    71 <entry>Description</entry>

    72 </row>

    73 </thead>

    74 <tbody>

    75 <row>

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

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

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

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

    80 </row>

    81 <row>

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

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

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

    85 from the SD Card Configuration Register (SCR). </p> </entry>

    86 </row>

    87 </tbody>

    88 </tgroup>

    89 </table> </section>

    90 <section id="GUID-BFBB02C3-1710-4F52-94C9-94386F8AEA5A"><title>Typical uses</title> <p>The typical uses for the SD card classes

    91 are the same as for MMC. </p> </section>

    92 </conbody><related-links>

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

    94 </link>

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

    96 Technology</linktext></link>

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

    98 Architecture</linktext></link>

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

   100 </link>

   101 </related-links></concept>