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<!DOCTYPE concept
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<concept id="GUID-90E2A645-56B0-4FC2-AE92-CD72FEC23AE6" xml:lang="en"><title>Input
and Output Functions</title><shortdesc>Describes the input and output functions involved in implementing
the Symbian platform GPIO class.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>There is no general reason why a pin which is available for use for GPIO
should not also be available for some other function, and the Symbian platform
GPIO specification allows for this. There are certain circumstances where
pin sharing should be prevented, for instance when a pin is in use as an interrupt
source, and these cases are specified individually.  </p>
<section id="GUID-84ACB7AB-F6DE-42F5-8C89-C7598FBC7AC1"><title>Implement the
Input/output functions</title> <ul>
<li><p>          Implement <xref href="GUID-EB28CB99-7191-345B-90FC-7708E9D190C7.dita"><apiname>SetOutputState()</apiname></xref> for each value
of          <xref href="GUID-7C1D78B4-9897-3C38-8EE7-7C311B885B0B.dita"><apiname>TGpioState</apiname></xref>.         </p> <ul>
<li><p>                Implement <xref href="GUID-EB28CB99-7191-345B-90FC-7708E9D190C7.dita"><apiname>SetOutputState()</apiname></xref> with
               <codeph>aState</codeph> == <xref href="GUID-ABF52F3A-CDC3-3AC6-89ED-FB7F5B781A25.dita"><apiname>ELow</apiname></xref> and return
value                <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.              </p> <p>  
             Verify that the pin is being used as a binary output. Set it
               to its low electric state.              </p> </li>
<li><p>                Implement <xref href="GUID-EB28CB99-7191-345B-90FC-7708E9D190C7.dita"><apiname>SetOutputState()</apiname></xref> with
               <codeph>aState</codeph> == <xref href="GUID-28B7F356-760B-38EA-90B1-AD3594375CBC.dita"><apiname>EHigh</apiname></xref> and return
value                <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.              </p> <p>  
             Verify that the pin is being used as a binary output. Set it
               to its high electric state.              </p> </li>
<li><p>                Implement <xref href="GUID-EB28CB99-7191-345B-90FC-7708E9D190C7.dita"><apiname>SetOutputState()</apiname></xref> with
               <codeph>aState</codeph> == <xref href="GUID-A538A8AF-DA50-3641-A794-19CAFF5B28F2.dita"><apiname>EDefaultIdleState</apiname></xref> and
return value                <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.              </p> <p> 
              Verify that the pin is being used as a binary output. Set its
               electric state to its default idle state.              </p> </li>
<li><p>                Implement <xref href="GUID-EB28CB99-7191-345B-90FC-7708E9D190C7.dita"><apiname>SetOutputState()</apiname></xref> with
return                value <xref href="GUID-F89DA3F0-2A48-3F9B-8F08-29350E92D0E4.dita"><apiname>KErrNotSupported</apiname></xref>.         
    </p> <p>                If the specified electric state is not supported
return                <xref href="GUID-F89DA3F0-2A48-3F9B-8F08-29350E92D0E4.dita"><apiname>KErrNotSupported</apiname></xref>.              </p> </li>
</ul> </li>
<li><p>          Implement <xref href="GUID-E88C05CA-8882-3C6A-9B64-8048DB7DA622.dita"><apiname>GetOutputState()</apiname></xref> with return
value          <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.         </p> <p>          Verify
that the pin is being used as a binary output. Determine          its electric
state and set <codeph>aState</codeph> to the appropriate value of        
 <xref href="GUID-7C1D78B4-9897-3C38-8EE7-7C311B885B0B.dita"><apiname>TGpioState</apiname></xref>.         </p> </li>
<li><p>          Implement <xref href="GUID-9BFB4B87-1400-33C0-B116-AC6FA349BE1E.dita"><apiname>GetInputState()</apiname></xref> with return
value          <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.         </p> <p>          Verify
that the pin is being used as a binary input. Determine          its electric
state and set <codeph>aState</codeph> to the appropriate value of        
 <xref href="GUID-7C1D78B4-9897-3C38-8EE7-7C311B885B0B.dita"><apiname>TGpioState</apiname></xref>.         </p> </li>
</ul></section>
</conbody></concept>