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<!DOCTYPE concept
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<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>