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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>