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

<concept id="GUID-C649DB97-F138-4C90-B177-16590F2E3F19" xml:lang="en"><title>DMA

Channels</title><shortdesc>This document describes how device drivers use DMA channels.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The DMAC has different DMA channels that can be configured for different

DMA transfers. Drivers generally initialise and open the required DMA channel

and use this channel to do the DMA transfers. For some peripherals, such as

the Camera and the Display controller, there can be dedicated DMA channels

that cannot be configured for DMA transfers by other peripherals. </p>

<p>Initialization and opening of DMA channels is done using the interface <xref href="GUID-83882548-FAC5-3EFF-92ED-14D1D9A85D37.dita"><apiname>TDmaChannel</apiname></xref>. </p>

<note>This class is designed only for single-thread client access. When used

by multi-threaded clients, synchronisation mechanisms should be provided by

the driver. </note>

<p>DMA channels must be opened before use and closed after completion of DMA

operations, as shown below. </p>

</conbody></concept>