Opening Dma Channels - Analog Devices VisualDSP++ 5.0 Service Manual

Opening DMA Channels

To open a DMA channel, the client calls the
The client passes into the function the following parameters:
• A handle to the DMA manager that controls the channel
• The channel ID (of type
DMA channel to open
• A client handle that is passed back to the client's callback function.
This is a client-supplied value, providing some meaning to the
client, which is passed back to the client's callback function so the
client can associate this value with the stream causing the callback.
• A pointer to a location into which the DMA manager stores the
channel handle. The channel handle is a DMA manager-defined
value that uniquely identifies the channel to the DMA manager.
• The operating mode that defines how the channel moves data.
Refer to the sections starting with
• A handle to a deferred callback service (typically from the deferred
callback service) or a NULL value. If a NULL value is supplied, the
DMA manager makes live callbacks to the application. Live call-
backs are made during hardware interrupt time. If a deferred
callback service handle is provided, all callbacks for the stream use
the deferred callback service to make callbacks occur at non-hard-
ware interrupt time.
• The address of the callback function that is called to notify the cli-
ent of events. Events may be expected events (such as requests for
notification when a transfer is complete) to unexpected events
(such as a DMA error). When the callback function is actually
invoked, deferred or live, depends on the callback service handle
value that is supplied.
VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors
adi_dma_Open()
ADI_DMA_CHANNEL_ID
"Single Transfers" on page
DMA Manager
function.
) that identifies the
6-12.
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