PCVisionplus
Hardware Reference
1–1
Rev 02; February 8, 2002
CHAPTER 1
INTRODUCTION
The PCVisionplus
frame grabber digitizes monochrome analog video to 8 or 12 bits, at sample frequencies up to 53
MHz. The PCVisionplus supports broadcast standard timing (RS170, CCIR), progressive scan and non-standard
(variable scan) timing. The PCVisionplus can support two monochrome cameras.
The high data transfer rate of the PCI-bus eliminates the need for on-board processing or display circuitry. Image
display and processing is handled by the host computer resources. The linear format image memory allows acquisi-
tion of a variety of image sizes. The image memory behaves as a temporary buffer between the camera interface and
the host PCI-bus system. The PCVisionplus incorporates a hardware “scatter gather” table for highly efficient, fully
automated image transfers from the image memory.
The PCVisionplus is capable of bus mastering image data directly to a destination memory within the PCI-bus sys-
tem, such as system memory or VGA memory. Transfer rates up to the theoretical PCI-bus limit of 133MB/s can be
sustained, depending upon the host capabilities. Images can be transferred to host memory in a fraction of the time
that they were acquired. By minimizing the PCI-bus transfer time and CPU overhead, more bandwidth is available
for processing or other system resources.
1.1 PCI INTERFACE
The PCI-bus interface allows the PCVisionplus to operate as both PCI-bus master and target (slave). Only DWORD
(32-bit) access is supported. The PCVisionplus is capable of bus mastering data from image memory directly to a
destination within the system (system memory or another PCI target, such as VGA display memory). The PCVision-
plus interface also supports target access to the registers and image memory. PCI-bus interrupts may be generated
based on events occurring on the PCVisionplus. The PCVisionplus provides configuration registers required by the
PCI specification which allow the board to be recognized on power-up for automatic system configuration (“plug-
and-play”).
The PCVisionplus contains a sophisticated bus master controller (BMC) with hardware scatter gather table. The host
CPU is free to perform processing during bus master transfers rather than controlling the transfer operation. The
BMC has multiple frame ping-pong source and destination capabilities which allow the application to program the
PCVisionplus to establish the needed amount of processing time. The BMC uses a programmable scatter gather table
that supports up to 32K host memory segments. The scatter gather table is also used to transfer images in an x,y
format directly to VGA memory for display, or re-interlace image fields from interlaced or dual-tap sources.
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