[Engineering Feature]
All A-Board!
To satisfy the needs of aerospace and defense applications, compact, multicore, low-power computer boards are achieving greater levels of computational capabilities per watt.
Aerospace and military applications that are more sophisticated and complex are spawning a new breed of single-board computers (SBCs). That’s because the users in these areas have rather formidable demands, such as greater ruggedness, higher reliability, more power performance, less power dissipation, and a smaller form factor.
As a result, board and systems integrators are scrambling to find ways to pack as much technology as possible on the smallest board practical. Some companies are using commercial off-the-shelf (COTS) technology. Others are employing multicore designs, in which a board may have several processors, some coming from different manufacturers.
Designers use a range of operating systems as well, often utilizing multiple operating systems like Unix, Linux, Microsoft’s Windows XP Pro and Embedded, and Wind River Systems’ VxWorks on a single board. In addition, high-speed serial buses are favored over older parallel buses to handle the higher-data-rate and wider-bandwidth communications of modern SBCs.
Although COTS components see wide use in SBC designs, their application sometimes depends on performance requirements and the design budget. Some SBC designs requiring very high performance levels may opt to use custom components should the design budget allow it.
Multicore COTS processing that incorporates leadingedge, high-performance processors promises to revolutionize SBC designs. The multicore approach eliminates the need for individual computer boards for each application. It also allows multiple applications to run from a single board, often from a single CPU. High-performance multicore processors can be found in many SBCs and plug-in support mezzanine cards.
MULTICORE COTS PROCESSING These multicore processors include Analog Devices’ Sharc and Blackfin; Freescale Semiconductor’s 8641 PowerPC and 8555E; Intel’s Core 2 Duo, Xeon Dual, and Pentium; AMD’s Turion 64, Opteron, and Radion HD3650; Sun Microsystems’ UltraSPARC IIi and IIIi; PA Semiconductor’s 1682; and the MIPS64 from Cavium Networks.
Jointly developed by Sony Computer Entertainment, Toshiba, and IBM, the Cell Broadband Engine (Cell BE) multicore processor architecture from supplier IPV Ltd. combines a modest general-purpose Power Architecture core with streamlined co-processing elements that greatly accelerate multimedia and vector-processing applications, as well as many other forms of dedicated computation (Fig. 1).
Ruggedness is a key parameter for aerospace and defense users of SBCs. With a 3U CompactPCI design, the S950 SBC developed by Aitech Defense Systems uses as little as 13.5 W in full operation and less than 8 W in sleep mode. It’s based on a PowerPC 750FX platform and features a radiation-tolerant anti-fuse FPGA that maintains memory control to ensure data integrity in harsh environments.
General Micro Systems also uses the CompactPCI approach in its Premonition CC279. This 6U, 100-W, conduction-cooled SBC is based on the user’s choice of two Intel Quad-Core or two Dual-Core Xeon processors (Fig. 2).
The use of field-programmable gate arrays (FPGAs) is another rising trend in SBC designs. FPGAs not only provide the required number-crunching and interfacing with high-speed serial buses, they also ease a designer’s migration from older-generation, FPGA-based designs without having to worry about the requirements for lead-free components.
An SBC can form an entire system on a board for a specific function. Or, several SBCs can be plugged into a backplane connector within a box-like metal cage for even higher performance. Some of these SBCs may not abide by SBC standards, though, since they may be entirely custom-made. Also, many specific-function mezzanine cards can plug into SBCs, like graphics accelerator mezzanine cards, display and other types of mezzanine controller cards, and memory mezzanine cards.
Developed by Mercury Computer Systems, the PowerBlock 50 crams a tremendous amount of power into a box-like product (Fig. 3). This 6- to 10-lb unit measures just 4 by 5 by 6 in., yet it delivers 100 GFLOPS of processing power. Optimized for embedded computing applications where space and weight constraints are important, the PowerBlock 50 uses the Cell BE multicore processor.
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