Chapter 3 Hardware Overview
© National Instruments Corporation 3-5 IMAQ PCI-1428 User Manual
duration of these signals in easy-to-use units. See the Interfacing with the PCI-1428 section
in Chapter 1, Introduction, for information on camera files.
Acquisition, Scaling, ROI
The acquisition, scaling, and region-of-interest (ROI) circuitry monitors
incoming video signals and routes the active pixels to the multiple-tap data
formatter and SDRAM. The PCI-1428 can perform ROI and scaling on all
video lines and frames. Pixel and line scaling transfers multiples of two,
four, or eight pixels and lines to onboar d memory. In an ROI acquisition,
select an area within the acquisition window to transfer across the PCI bus
to system memory.
Note You can use MAX to set the acquisition, scaling, and ROI parameters.
Scatter-Gather DMA Controllers
The PCI-1428 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. The PCI-1428 can perform continuous image
transfers directly to either contiguous or fragmented memory buffers.
Bus Master PCI Interface
The PCI-1428 implements the PCI interface with a National Instruments
custom application-specific integrated circuit (ASIC), the PCIMITE.
ThePCI interface can transfer data at a maximum rate of 133 MB/s
inbus master mode.
Start Conditions
The PCI-1428 can start acquisitions in the following ways:
• Software control—The PCI-1428 supports software control of
acquisition start. You can configure the PCI-1428 to capture a fixed
number of frames. This configuration is useful for capturing a single
frame or a sequence of frames.
• Trigger control—You can start an acquisition by enabling external
orRTSI bus trigger lines. Each of these inputs can start a video
acquisition on a rising or falling edge. You can use all four external
triggers and up to four RTSI bus triggers simultaneously.