Data Translation DT3155, User Manual

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Principles of Operation
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Acquisition Modes
The DT3155 board can acquire interlaced frames synchronously or
asynchronously and store them in system memory.
In a synchronous acquisition, you cannot perform another operation
until the synchronous acquisition completes. In an asynchronous
acquisition, the operation starts but gives control to you immediately,
allowing you to perform other operations while data is acquired.
Using the DT3155, you can acquire single frames to an area in system
memory that was either allocated to the DT3155 Device Driver
during system startup (called
device memory ) or provided by you
(called host memory ).
An interrupt is generated when an even field or an odd field has been
acquired; the PCI bus assigns the interrupt to the DT3155 board
automatically when it is installed.
The speed of the PCI bus allows the DT3155 to transfer an unlimited
number of consecutive frames across the bus in real time. You can
acquire and store consecutive images, up to the capacity of available
system memory.
Acting as a PCI bus master, the board sends pixel data over the PCI
bus directly using burst transfer rates up to 30 frames/s for 60 Hz
image formats and 25 frames/s for 50 Hz image formats. Note that a
16-bit color display adapter is required when performing overlays
(DDI).