Embedded systems that require small rugged form factors can take advantage of off-the-shelf PC/104 and PC/104+ imaging boards.
By Andrew Wilson, Editor
In their latest embedded-imaging frame-grabber boards, vendors are embracing the newest interfacing standards, such as Camera Link, Universal Serial Bus (USB), FireWire (IEEE 1394), and the embedded PC/104 format. Gate arrays coupled with numerous I/O options such as Ethernet and digital I/O are allowing such boards to be used in embedded scientific, machine-vision, medical, and military applications.
The initial release of the PC/104 specification in March 1992 was an open design that offered the power and flexibility of an IBM-compatible PC in a size for embedded systems. Today, PC/104 system components are used in many industrial applications including machine-vision and control systems. Repackaged for industrial use, the PC/104 emerged from the PC ISA bus packaged in a 3.6 × 3.8-in. form factor. Although the specification of the PC/104 bus is the same as the ISA bus, the current drive capability is limited to approximately 4 mA.
When demand for a PCI bus emerged, PC/104+ technology was added in February 1997 by the PC/104 Consortium (San Francisco, CA, USA) as an addition to the technology. PC/104-Plus (or PC/104+) is the PCI implementation of PC/104. To support the 33-MHz PCI bus, a 120-pin connector was added to the PC/104 connector. To expand both the PC/104 and PC/104+ based systems, boards are stacked on top of one another. Using the PC/104+ specification, developers can add up to four I/O cards to each system stack. To build such systems, designers can choose from a large number of CPU, frame-grabber, Ethernet-networking, wireless, and DSP boards.
To find these products, developers can access several Web sites that feature both PC/104 and PC/104+ products. The PC/104 Consortium site, for example, features more than 100 companies and more than 1000 products. Other useful sites include Arrick Publishing's E-Zine of PC/104 Controlled Systems (www.controlled.com/pc104) and the PC/104 Embedded Solutions Magazine (www.pc104-embedded-solns.com) from OpenSystems Publishing (St. Clair Shores, MI, USA; www.opensystems-publishing.com).
For the developer of machine-vision systems, the PC/104 and PC/104+ form factors allow relatively complex systems to be developed using just a few boards. Rather than build PC-based systems, developers can choose from highly integrated frame grabbers, CPU boards, display controllers, and other peripherals to build rugged systems. And, because of the relatively low cost of the boards, embedded systems can be easily upgraded at relatively low cost.
Broadcast standards
"Many of our competitors have abandoned PC/104 because of the form factor," says Daniel DeConinck, senior engineer at PixelSmart (Lewiston, NY, USA). One such company is CyberOptics Semiconductor (Beaverton, OR, USA), which discontinued its monochrome, RS-170, and CCIR frame-grabber line in the PC/104 form factor.
"We have discontinued our PC/104 offering for some time now," says Amalia Nita, product marketing manager at CyberOptics Semiconductor, which acquired the imaging business of ImageNation (Beaverton, OR, USA), " but we still fulfill orders for existing projects although this has never been a major part of the company's business. My research indicates that embedded form factors collectively represent about 10% to 15% of the available computing market. Also those who use embedded systems seem to belong to industries we don't serve, such as telecommunications, medical, and business servers."
PixelSmart and more than 20 other vendors currently produce PC/104 and PC/104+ based products that can capture composite (broadcast-compatible), analog, and digital signals, including standards-based signals from Camera Link, FireWire, and USB interfaces. PixelSmart offers the PixelSmart 512-8 video frame grabber, a PC/104 board that is typical of many broadcast-standards-based frame grabbers now available (see table on p. 48). Capable of digitizing NTSC and PAL signals, the board is supported by the Victor Image-Processing Library from Catenary Systems (St Louis, MO, USA) and the ImageJ (rsb.info.nih.gov/ij/) Java-based image-processing package written by the National Institutes of Health (Bethseda, MD, USA; see Fig. 1).
Also capable of digitizing NTSC, PAL, and SECAM signals, the CM7326 video frame-grabber card from Real Time Devices (RTD; State College, PA, USA) is supplied with drivers and examples for DOS, Windows, and Linux. According to Myron Semack, RTD manager of software engineering, many of the company's customers have used multiple CM7326s in a PC/104+ based system for surveillance systems. RTD DSP boards also can be used in combination with the frame grabber to process images in real time.
Imaging computers
Semack has used his company's Texas Instruments TMS320C6202-based 233-MHz SPM6030 DSP board with a CM7326 to perform real-time edge detection on a camera feed for collision-avoidance applications. Currently, the company is developing a PlatformBus frame grabber that can feed frames directly to DSP memory without using the PCI bus, leaving the PCI bus free for Ethernet and USB functions. For fast image processing, the company has prototyped its SPM386420 DSP board based on the 600-MHz Texas Instruments C6416 DSP. According to Semack, running the same real-time edge-detection application on the DSP results in a 2.5X improvement in speed.
AnaLogic Computers Ltd. (Budapest, Hungary) has used RTD's PC/104+ DSP modules, CPU boards, hard drive, network modules, and PC/104+ boards with its ACE4k visual microprocessor-based imaging module to design a cellular-neural-network-based imaging computer (see Fig. 2 on p. 46). This module contains 4096 processors that are arranged in a 64 × 64 grid to process 64 × 64-pixel image segments at up to 10,000 images/s. After the computationally complex preprocessing phase is accomplished by the ACE4k, an RTD SPM 6020 DSP completes the task.
Active Silicon Ltd. (Uxbridge, Middlesex, UK) also makes a PC/104+-based image digitizer as part of its LFG series. The board can select one of four composite/monochrome sources or three composite and one S-video signal. Software support includes Windows 98/NT/2000/ME/XP, DOS, Mac OS X, Linux, and VxWorks under a common API (see Fig. 3 on p. 46). The board's software-development kit includes a license for the company's TMG Imaging Library, which includes JPEG and wavelet compression, decompression, various pixel data mappings, and image display.
PC/104 boards are also being used in embedded military applications. For example, Advanced Micro Peripherals (AMP; Cambridge, UK) PC/104 boards have been used for a range of image capture, video overlay, and display applications. "Our MPEG1000 MPEG-encoding frame grabber is being used in combination with our Micro886 PC/104+ computer to develop a homeland-security device," says Lee Foss, technical director of AMP. The video server can be fitted to a police car, plane, or patrol boat to record up to four video channels simultaneously and stream WireLess (802.11x) live video to hand-held devices such as iPAQ Pocket PCs. "Using the device, a police helicopter equipped with the video server device can stream video to an officer on the ground for tracking purposes," he adds.
Interface standards
Interestingly, only two companies, Matrox Imaging (Dorval, QC, Canada) and PLD Applications (Aix-en-Provence, France), offer Camera Link-compatible PC/104+ boards. However, according to Andrew Buglass, product marketing manager, next month Active Silicon will introduce a single Base-configuration Camera Link interface board for the PC/104+ bus.
All Matrox Meteor-II frame grabbers are available as PC/104+ boards and can be used in any PC/104+ system. Individual boards are capable of digitizing signals from broadcast video standards, as well as analog, digital, Camera Link, and FireWire interfaces, and are supported under Windows 98/ME/NT/2000/XP (see Fig. 4). The company has made its Orion board available as a PC/104+ module that can be used with its 4Sight-II, an industrial computer that integrates image capture, processing, display, networking, and general-purpose I/O.
PLD Applications offers a PC/104+ form-factor board—the PC/104 +XSYS. This board features a Base-configuration Camera Link interface—a programmable device for on-board custom processing functions such as LUTs, ROI, camera gain and offset—and four optoelectronic inputs for triggering.
While the embedded-computing-systems market is relatively small compared with the general-purpose computing industry, it is not surprising that most PC/104 frame grabbers currently support only analog broadcast formats. Despite this, some companies, most noticeably Matrox, have recognized the need to offer a broader product range capable of supporting NTSC/PAL, analog, digital, Camera Link, and FireWire digitizers in the PC/104 embedded format. With such a range of hardware interfaces supported by the Matrox Imaging Library, Matrox is currently setting the PC/104 standard.
Click here to downloadPC/104-based frame grabbers for embedded applications table. {pdf size=502K}
