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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE concept |
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11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
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12 <concept id="GUID-113B3755-1797-5D1B-8E07-8A18F5FE1504" xml:lang="en"><title>Power |
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13 States</title><shortdesc>Describes three power states that are defined by the Kernel.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
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14 <ul> |
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15 <li id="GUID-61A3C566-05AA-5F6D-A9DE-B409C873B119"><p> <i>Off</i> - a state |
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16 where the device and all peripherals are powered off or inactive, or are characterised |
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17 by negligible power consumption due to current leakage to the electric and |
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18 electronic circuits that make up the system. This state is achieved as a result |
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19 of controlled system shutdown resulting from a user action, an application |
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20 request, UI inactivity, or as a result of accidental loss of power. This may |
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21 also be achieved as a result of putting the system into a hibernation state. |
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22 Note that a reboot is necessary to return the system to the <i>Active</i> state; |
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23 this could be a cold reboot, or a warm reboot if the system was put into a |
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24 hibernation state. </p> </li> |
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25 <li id="GUID-275417B2-B8C8-5C93-B576-15543D80CAC9"><p> <i>Standby</i> - a |
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26 low power consuming state that results from turning off most system resources |
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27 (clocks, voltages), peripherals, memory banks (where possible), cpu and internal |
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28 logic, while still retaining the state prior to the transition. Typically, |
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29 the only systems that are active are those that are required to detect the |
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30 events that force the transition back to the Active state (e.g. RTC, clocks |
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31 and Peripherals involved in detecting hardware events). Returning to the Active |
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32 state will normally take a far shorter period of time than that required to |
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33 reboot the system. This state is achieved as a result of user action or application |
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34 request. </p> </li> |
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35 <li id="GUID-A31A5A3C-C7C2-5D15-88B2-828F7E5F60D8"><p> <i>Active</i> - the |
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36 fully active state. </p> </li> |
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37 </ul> |
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38 <p>The three power states are defined by the enum values of the <xref href="GUID-87AB8B20-04EE-31D2-8F3D-EA904D05B8D0.dita"><apiname>TPowerState</apiname></xref> enum |
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39 defined in <filepath>e32power.h</filepath>. </p> |
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40 </conbody><related-links> |
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41 <link href="GUID-E09E4418-4DC3-56A3-BFBE-486C9C8D25C9.dita"><linktext>Domain Manager</linktext> |
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42 </link> |
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43 <link href="GUID-0C435514-EEC6-5660-BB5F-535790349632.dita"><linktext>Power Management</linktext> |
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44 </link> |
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45 </related-links></concept> |