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<task id="GUID-4B709839-8EEF-4AD2-9868-9AF0176B1E5B" xml:lang="en"><title>Using

Sensor Channels APIs</title><shortdesc>The Sensor Channel establishes a data exchange connection between

the sensor framework and hardware using the sensor channel APIs.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>

<steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-7-1-8-1-1-8-1-4-1-5-1-3-1">

<step id="GUID-9A69E5AD-E938-4092-A8C2-CB65C37C8962-GENID-1-7-1-8-1-1-8-1-4-1-5-1-3-1-1"><cmd>Include the library <b>SensrvClient.lib</b> in

your <b>.mmp</b> file.</cmd>

</step>

<step id="GUID-4F637EBD-BD56-44FA-A984-E93CC4B2B3B6"><cmd>Include the following

header files, as they are required for accessing sensor channels regardless

of the channel type: </cmd>

<info><ul>

<li><p>sensrvchannel.h</p></li>

<li><p>sensrvchannelinfo.h</p></li>

<li><p>sensrvtypes.h</p></li>

<li><p>sensrvchannelfinder.h</p></li>

<li><p>sensrvdatalistener.h</p></li>

</ul><p>In addition to these, include the

necessary header files based on the type of channel to be used. For information

about channel-specific header files, see <xref href="GUID-F1935106-C730-4C64-A19A-0FC04F0E7121.dita">Types

of Sensor Channels</xref>.</p></info>

</step>

<step id="GUID-F5BC52B6-67DD-4F59-889B-C5DE4C69029B"><cmd>Retrieve details

about the required sensor channel. For details. see <xref href="GUID-44FDDA27-1A5D-42B5-8DE0-D9E88EB75C93.dita">Querying

for Sensor Channels</xref>.</cmd>

</step>

<step id="GUID-FBBD3A8B-F240-4DC0-B516-3A51FDD86A88"><cmd>Connect to the sensor

by opening a connection with the sensor channel.</cmd>

<substeps id="GUID-C9E5B9FC-C637-4DEB-AAAF-E38C6CD9A18A">

<substep id="GUID-CA2CFF9C-3168-4060-AC39-8CB6FBA4BCA2"><cmd>Create an instance

of <codeph>CSensrvChannel</codeph> and specify the instance of <codeph>TSensrvChannelInfo</codeph> returned

by <xref href="GUID-5F108D03-C8A6-3EF9-B103-2E8916633602.dita#GUID-5F108D03-C8A6-3EF9-B103-2E8916633602/GUID-E58BAF1B-57AA-3E85-A4F9-8C6C29043FBD"><apiname>CSensrvChannelFinder::FindChannelsL()</apiname></xref>, as a parameter

in the <codeph>NewL()</codeph> constructor.</cmd>

<stepxmp><codeblock xml:space="preserve"> CSensrvChannel* sensorChannel;

 sensorChannel = CSensrvChannel::NewL(channelInfoList[0]);// channelInfoList is

//   returned by the CSensrvChannelFinder::FindChannelsL()funtion</codeblock></stepxmp>

</substep>

<substep id="GUID-30E6033F-E316-4BDB-AF22-2369463DF709"><cmd>Open the sensor

channel using <xref href="GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844.dita#GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844/GUID-277A4940-2E5E-3E8E-AB61-552CD2375F3C"><apiname>CSensrvChannel::OpenChannelL()</apiname></xref> function.</cmd>

<stepxmp><codeblock xml:space="preserve">channel-&gt;OpenChannelL();</codeblock></stepxmp>

</substep>

</substeps>

</step>

<step id="GUID-7A414271-040C-4107-B047-9416747C66A6"><cmd>Perform any of the

following operations:</cmd>

<info><ul>

<li><xref href="GUID-BA0D9DA9-3B54-4964-A4D6-9ADA4DEB7231.dita">Receive data from

sensors</xref></li>

<li><xref href="GUID-09E44FE5-6BEE-49FF-8BBF-CBB3C066EE10.dita">Listen for channel

changes</xref></li>

<li><xref href="GUID-83630B57-D842-4B60-8AF0-D2965251DE29.dita">Retrieve channel

properties</xref></li>

<li><xref href="GUID-0CA7F22E-59D7-4D65-9D6C-735E4E0F0454.dita">Set channel properties</xref></li>

<li><xref href="GUID-E93EE459-8CF4-42A1-B06C-E78E56FD25A0.dita">Listen for channel

property changes</xref></li>

<li><xref href="GUID-60EE22AA-402D-4FC2-9AD1-B3AEF822E8DC.dita">Receive channel

data based on conditions</xref></li>

</ul></info>

</step>

<step id="GUID-61840C55-476C-4DC3-A946-A440330B9DE5"><cmd>Close the channel.</cmd>

<info><codeblock xml:space="preserve">channel-&gt;CloseChannel();</codeblock><note type="important"> A

channel must be closed when not required, as it reduces power consumption

of the Symbian device. An open sensor channel keeps the device processor active

each time data arrives. Therefore, the processor does not change to idle state

even when the device user is not performing any operations on the device.</note></info>

</step>

</steps>