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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-490C3D1E-58B0-5295-BB56-87BD77F5D33E" xml:lang="en"><title>Device
Driver Helper Suite Overview </title><shortdesc>This document provides an overview of the Device Driver Helper
Suite. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<section id="GUID-6C03BA8C-7615-4ACB-866C-6CFE42DDD91B"><title>Purpose</title> <p>The Device Driver Helper Suite is a set
of APIs which provides a standard interface from Symbian platform to proprietary
hardware. </p> </section>
<section id="GUID-138063EC-497F-42D8-A09E-0A321CA68E5C"><title>Architectural Relationship</title> <p>The Device Driver Helper
Suite consists of four modules corresponding to four generic types of hardware: </p> <ul>
<li id="GUID-854C33DD-ADCF-5A5D-B339-CFDC3847B28B"><p>IIC buses </p> </li>
<li id="GUID-CF57BD6F-F2F0-5390-B1F2-986AC537B90D"><p>I2S buses </p> </li>
<li id="GUID-F036F24D-EA69-595D-8278-EB3C320E9B16"><p>GPIO </p> </li>
<li id="GUID-0C855E0E-0988-5EA1-B303-C000285E9206"><p>Hardware registers. </p> </li>
</ul> <p>The four modules are related by functionality since they all consist
of interfaces which enable Symbian platform to communicate with external devices.
The modules are not related in a class hierarchy. </p> </section>
<section id="GUID-EE68DDD8-8B9C-4B55-9DE7-807F27E66DFA"><title>Description</title> <p>Hardware devices have numerous different
instruction sets which are specific to the different manufacturers. The Device
Driver Helper Suite serves two groups of people. Firstly it insulates Symbian
platform developers from specific instruction sets by providing them with
generic interfaces to classes of hardware. Secondly it gives hardware manufacturers
a standard interface which they implement to provide compatibility with Symbian
platform. </p> </section>
<section id="GUID-3607B5AA-C3A8-4E1A-9A7D-1DC06CA434A1"><title>Components</title> <p>The four components of the Device Driver
Helper Suite correspond to four ways of accessing hardware. IIC and I2S are
two different methods of accessing hardware over buses, GPIO accesses hardware
over pins, and registers are used to access hardware directly. </p> <p><b>IIC</b> </p> <p>IIC (Inter-IC) buses are serial buses used to exchange data between
different components of a hardware system, typically where the exchange is
not time-critical. </p> <p><b>I2S</b> </p> <p>I2S
(Inter-IC Sound) is a bus standard developed by Philips to model the interface
between producers and consumers of digital audio data connected together in
a CPU-based system. </p> <p><b>GPIO</b> </p> <p>GPIO
(General Purpose Input-Output) is a type of input-output over pins or pads
which are grouped in modules or banks of up to 32 pin or pads each. </p> <p><b>Hardware registers</b> </p> <p>A hardware register is a physical interface
to an item of hardware at the level of the bit. They are typically used to
access Application Specific Standard Product (ASSP), a class of integrated
circuit, and are then called ASSP registers. </p> </section>
<section id="GUID-5666E2A6-84AE-472D-B3E8-1D00ECF16E21"><title>Using the Device Driver Helper Suite</title> <p>Two different
kinds of programmer use the Device Driver Helper Suite: device driver writers
and platform implementers. </p> <ul>
<li id="GUID-5D06B95F-6935-5379-80A6-67FB837276E4"><p>Device driver writers
use the Device Driver Helper Suite as part of the user side of Symbian platform
Base library to write device drivers. </p> </li>
<li id="GUID-9094F5BA-DDF7-5B1C-B81C-71E8A376BCFE"><p>Platform creators implement
the Device Driver Helper Suite when porting Symbian platform to new hardware. </p> </li>
</ul> </section>
</conbody><related-links>
<link href="GUID-52371DAB-A231-558C-B3E6-220DAAEE566B.dita"><linktext>Logical Device
Drivers</linktext></link>
</related-links></concept>