The promise of COM Express

A GE Intelligent Platforms perspective on embedded military electronics trends.

Cost pressures continue to bedevil military programs. Years of fighting have taken a toll on equipment, while years of sequestration have made upgrading or replacing the equipment more difficult. Budget constraints require everyone involved to pay the utmost attention to life cycle costs at all levels of procurement.

Although commercial off-the-shelf (COTS) technologies yield savings by exploiting the economies of scale available in the consumer market, there is a major tradeoff. Consumer products – along with the electronic components inside them – are intended for benign environments, whereas military products operate in some of the world’s most demanding environments.

Electronic systems in missiles, tanks, and airborne platforms must thrive amid high levels of shock and vibration and be able to withstand extreme temperature swings. Resistance to dust, sand, and salt spray also may be required.

In addition, military computers must provide high, and continually increasing, levels of performance as applications evolve; all of this must occur in small size, weight, and power (SWaP) packages. What’s more, these systems must endure not simply for years, but for decades, as commercial technologies come and go. The implementation of concepts like network-centric warfare has only underscored the need for high-power, high-bandwidth, and easily upgradable electronics. The perennial question for designers of high-performance embedded computing (HPEC) systems then becomes: How to provide the best technologies from the commercial market in the bulletproof packages required by military applications?

COM Express – from commercial to military

A recent instance of this synergy is the ruggedization of computer-on-module (COM) Express technology. COM modules were developed to insulate computer boards from processor churn. Before their invention, designers of single-board computers had to rethink their layouts each time their processors went out of production. Adopting a new integrated circuit required designers to develop supporting silicon, as well as low-level software and firmware. This setup typically entailed board redesigns with the accompanying costs and delays.

Like most innovations in electronics, COM modules were introduced in proprietary packages but were eventually standardized in a range of sizes and pinouts. A popular set of COM module configurations, known as COM Express, was developed by the PCI Industrial Computer Manufacturers Group (PICMG). Today COM Express is widely used in commercial applications from gaming to health care.

The beauty of COM Express is that when a processor reaches end-of-life, it can be replaced with a new-generation, plug-in processor module without disturbing the underlying hardware. The carrier board can be a standard backplane module like VME or VPX or a customized format to support the particular size and input/output (I/O) demands of a military user. Furthermore, when upgrades become necessary, system downtime is minimal. The standard even specifies a module heat-spreading interface which can be combined with a designer’s proprietary cooling approach.

Ruggedizing COM Express

COM Express was not developed for high-stress environments, however; after it became a commercial standard of potential interest to military users, there was still the task of ruggedizing the modules. This step has been achieved by measures such as screening components, developing specialized cooling technologies, and thoroughly testing products to specifications such as MIL-STD-810 and VITA 47. Soldering rather than socketing components to modules further increases resistance to shock and vibration by reducing the number of mechanical connections.

One example of a recent rugged COM Express product is the GE Intelligent Platforms bCOM6-L1700 module, hosting AMD’s latest R-Series system-on-chip processor and as much as 16 GB of soldered memory (Figure 1).

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Figure 1: The bCOM6-L1700 rugged COM Express module from GE features AMD’s latest R-Series system-on-chip processor.
(Click graphic to zoom by 1.9x)

Rugged modules exist today using multiple IC types, while new developments in the manufacture of memory chips permit previously unheard-of module densities. Above all, the ruggedizing of COM Express technology has made it attractive to applications such as missiles and unmanned vehicles.

For military customers the benefits are compelling: When the time comes to upgrade a module, complex I/O cabling can be left in place. This configuration avoids the necessity of detaching wires and possibly misconnecting them, as well as the need to retest signal integrity after the configuration is restored. Wear and tear on board connectors is also reduced, extending system life on multiple fronts.

While COM Express technology is relatively new to the military world, the initial upfront investment promises to yield dividends by providing a low-risk path to incremental upgrades at acceptable lifecycle cost.

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