In today’s mil/aero industry, there has been a shift from customized, proprietary solutions to leveraging COTS building blocks in the deployment of mobile, mission-critical and high-performance applications. Mobile computing applications such as portable and in-vehicle computers must be rugged enough to handle the toughest environmental factors, yet efficient enough to meet application needs for power and heat dissipation. 

As new processing technology hits the market, there has been an explosion of innovation in small form factor modules. These new processors enable high computing power along with low electrical power consumption; an ideal combination for mobile computing applications deployed in harsh environments. Combining a processor module with a small form factor carrier board can deliver a scalable and flexible method to create a customized system. COM Express’ modular design helps designers meet the unique enclosure needs of military applications. 

Why COM Express? 

As network-centric military systems raise the bar on compute, I/O and graphics performance, older modular form factors are unable to support the power requirements on multicore processors and limit the I/O, memory and video interfaces. The PICMG COM Express standard comprehends the latest I/O and graphics integration and supports these interfaces natively via the processor/chipset, providing customers upgrade and performance options on board rather than via add-in cards. In addition, COM Express-based solutions are highly integrated and compact, delivering high-performance processing within a small, low-power embedded form factor, making it an ideal platform for portable, battery-powered applications. Figure 1 shows an example of a COM Express board from Radisys.

Original Equipment Manufacturers (OEMs) can avoid the design churn that comes with implementing new processor generations by adopting COM Express, a two-board solution that is uniquely capable of delivering ruggedness and power efficiency. The platform comprises a computer-on-module (including processor, chipset and memory) and a carrier board that can be customized to specific application requirements. Manufacturers can leverage COTS computer modules and design their own carrier boards, which may include differentiating features and proprietary I/O. Table 1 lists some of the key computer-on-module selection criteria.

When designing a small form factor system with COM Express, there are several design considerations to take into account. These include selecting the optimal processor for the application power budget, designing for extended temperature and vibration specification requirements, and ensuring rigorous testing. 

Selecting the Processor 

Contrary to the belief that the lowest power solution dominates, mil/aero customers want the highest performing processor that they can run reliably with their application’s power budget. To achieve this combination, the COM Express processor module must be thoroughly validated, tested and documented to meet the required temperature range. Boosting the performance of mainstream processing performance can be done, but is especially challenging for designers of small form factor systems who face stringent space and power constraints.

These products must be capable of operating in extended temperature ranges, from -25° to +70°C. However, the mainstream performance processors are not specified or guaranteed to meet these extended temperature ranges, and design engineers must rely on extended testing at the board or system level to ensure the processor’s reliability. Some embedded computer vendors provide this critical step by analyzing and validating new processing technology over the extended temperature range as it hits the market, ensuring that the thermal dissipation and performance of its modules can meet the requirements of the harsh mil/aero environments. 

Extended Temp and Vibration Specs

Radisys designs ruggedness into its COM Express modules by employing its proprietary Highly Accelerated Life Testing (HALT) techniques during the design phase. HALT is used in the design phase to maximize the full limits of the product design. An effective strategy for testing consists of a stepped thermal and vibration stress process during which the actual limits of the design and component performance are determined. As failure modes are discovered, they are corrected by design or component improvement until no further improvement is practical or is limited by the fundamental limit of the underlying technologies. By establishing that the design and components are capable of operating not only to the extended temperature specification, but well beyond, HALT demonstrates the true operational limits of the product.