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<concept id="GUID-74FE6572-14B9-4B94-8DD0-803DA21D14A3" xml:lang="en"><title>Wakeup

Functions</title><shortdesc>Describes the wakeup functions involved in implementing the Symbian

platform GPIO class.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>One important use of GPIO input pins is to signal a wakeup request to the

CPU. Wakeup requests will usually take place when the system is idling and

clocks are switched off. This means that the kind of trigger used to signal

wakeups must be detected asynchronously (not on a clock edge) and hence that

a wakeup trigger should probably be configured for edge detection and not

level detection. Since a wakeup is generic to the whole CPU regardless of

its origin, wakeups are usually combined into a single signal by a logical

OR operation. </p>

<section id="GUID-19811A8B-5A8F-4769-8686-1BB49C56532F"><title>Implement the

wakeup functions</title> <ul>

<li><p>                Implement <xref href="GUID-1C41DDCD-7BE3-3BDA-A832-C2C9821AEB09.dita"><apiname>EnableWakeup()</apiname></xref> with return

               value <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.              </p> <p>  

             Enable wakeup on the pin.              </p> </li>

<li><p>                Implement <xref href="GUID-21432D3C-90DA-35AA-AFB5-C7FF37ED0806.dita"><apiname>DisableWakeup()</apiname></xref> with return

               value <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.              </p> <p>  

             Disable wakeup on the pin.              </p> </li>

<li><p>                Implement <xref href="GUID-D58B6C13-F3B0-3E18-A7ED-DE177BC2CCEB.dita"><apiname>IsWakeupEnabled()</apiname></xref> with

return                value <xref href="GUID-6CA4F1ED-7947-3087-B618-D35858FAA3BC.dita"><apiname>KErrNone</apiname></xref>.              </p> <p> 

              Verify that the pin supports wakeup and determine the wakeup

               state. If is enabled set <xref href="GUID-28B9AB57-B1B6-3D84-A118-FAEA5AD2C23F.dita"><apiname>aEnable</apiname></xref> to True

and if it is                disabled set <xref href="GUID-28B9AB57-B1B6-3D84-A118-FAEA5AD2C23F.dita"><apiname>aEnable</apiname></xref> to False.

             </p> </li>

<li><p>          Implement these functions with return value          <xref href="GUID-F89DA3F0-2A48-3F9B-8F08-29350E92D0E4.dita"><apiname>KErrNotSupported</apiname></xref>:

        </p> <ul>

<li><p>                <xref href="GUID-1C41DDCD-7BE3-3BDA-A832-C2C9821AEB09.dita"><apiname>EnableWakeup()</apiname></xref>              </p> </li>

<li><p>                <xref href="GUID-21432D3C-90DA-35AA-AFB5-C7FF37ED0806.dita"><apiname>DisableWakeup()</apiname></xref>              </p> </li>

<li><p>                <xref href="GUID-D58B6C13-F3B0-3E18-A7ED-DE177BC2CCEB.dita"><apiname>IsWakeupEnabled()</apiname></xref>              </p> </li>

</ul> <p>          Return <xref href="GUID-F89DA3F0-2A48-3F9B-8F08-29350E92D0E4.dita"><apiname>KErrNotSupported</apiname></xref> if the pin does

not          support wakeups.         </p> </li>

</ul>  </section>

</conbody></concept>