National Instruments Printer PCI-1405 User Manual download pdf (Page 14)

Chapter 2 Hardware Overview

Acquisition and ROI Circuitry

The acquisition and region-of-interest (ROI) circuitry monitors the

incoming video signals and routes the active pixels to the SDRAM

memory. The NI 1405 can perform an ROI acquisition on all video lines

and frames. In an ROI acquisition, you select an area within the acquisition

window to transfer to the PCI bus.

Scatter-Gather DMA Controllers

The NI 1405 uses three independent onboard direct memory access (DMA)

controllers. The DMA controllers transfer data between the onboard

SDRAM memory buffers and the PCI bus. Each of these controllers

supports scatter-gather DMA, which allows the DMA controller to

reconfigure on-the-fly. Thus, the NI 1405 can perform continuous image

transfers directly to either contiguous or fragmented memory buffers.

Bus Master PCI Interface

The NI 1405 implements the PCI interface with a National Instruments

custom application-specific integrated circuit (ASIC), the PCI MITE. The

PCI interface can transfer data at a maximum rate of 132 Mbytes/s in

bus master mode. The NI 1405 can generate 8-, 16-, and 32-bit memory

read and write cycles, both single and multiple. The interface logic ensures

that the NI 1405 can meet PCI loading, driving, and timing requirements.

Start Conditions

The NI 1405 can start acquisitions in a variety of conditions:

• Software control—The NI 1405 supports software control of

acquisition start. You can configure the NI 1405 to capture a fixed

number of fields or frames. Use this configuration for capturing a

single frame or a sequence of frames.

• Trigger control—You can start an acquisition by enabling the

external trigger line. This input can start a video acquisition on a

rising or falling edge.

• Frame/field selection—With an interlaced camera and the NI 1405 in

frame mode, you can program the NI 1405 to start an acquisition on

any odd or even field.

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National Instruments Printer PCI-1405 User Manual Page 14