Rugged, reliable COMs add value to military avionics design
Sophisticated avionics systems and platforms are advancing rapidly, particularly as unmanned aircraft handle a greater number of essential security and surveillance missions. In this environment, high-performance, Small Form Factor (SFF) platforms are in demand as enablers of superior intelligence gathering and improved, real-time situational awareness. COM Express-based Computer-on-Modules (COMs) are proving their mettle by answering today’s performance requirements for graphics, low power, and rugged reliability, while providing a cost-effective migration path that is in step with evolving avionics applications.
Avionics technology continues its rapid advance, creating safer and more sophisticated airborne environments. Yet even as technology boundaries are pushed to enable enhanced communications, navigation, weapons control, and more, the demanding physical restrictions within an aircraft remain consistent. Designers face rigorous performance considerations such as Size, Weight, and Power (SWaP), shock and vibration, thermal requirements, and altitude issues, as the broad spectrum of military aircraft includes manned and unmanned vehicles that must support an incredible range of missions and payloads.
These strict requirements all must be addressed with embedded computing solutions that offer High Availability (HA), airborne-compatible performance with reduced deployment and operating costs. SFF platforms, such as COMs, are optimized for this type of extreme military design, coupling rugged and extended temperature options with small, mobile, and power-efficient design capabilities. Ruggedized modules based on the COM Express standard, hosted by the PCI Industrial Computer Manufacturers Group (PICMG), offer an ideal option for Commercial-Off-The-Shelf (COTS)-based airborne networking applications. Avionics applications in particular, with their uncommonly demanding environmental restraints, are benefiting from the compute-power and reliable performance delivered by these compact components.
Optimal SWaP comes in small packages
As a nearly complete computer mounted on a carrier board, COM Express-based COMs can be considered application-ready platforms that are well suited for these types of rugged, high-performance deployments. COM Express offers the smallest form factor available for military systems, offering a size excellent for SWaP considerations coupled with customizable I/O options. The standard’s smallest form factor is the “Mini,” about the size of a credit card at 55 mm x 84 mm (Figure 1). Its extremely low power consumption and small format are well suited to mobile battery-powered and inexpensive applications. Their wide-ranging power input (from 5V to 14V) make them an ideal fit for small form factor avionics applications, particularly considered in tandem with their ability to handle extreme environmental conditions and temperature ranges from -40 °C to +85 °C.
The “Basic” (95 mm x 125 mm) and “Compact” (95 mm x 95 mm) COM Express form factors are recognized successors to the legacy ETX form factor that set the standard for COM modules. The Compact form factor is ideally suited for space-critical or mobile applications, and its interfaces, pin-outs, and connector placements are 100 percent compatible with the Basic form factor and support a wide power input range of 8.5V to 18V. Attachment holes and cooling concepts for the Basic and Compact form factors are identical, assuring extremely simple interchangeability on carrier boards for flexibility of design and a forward path to continually improve performance.
Any of these modules can incorporate today’s most advanced x86 processors, delivering graphics and processing performance that would have previously required multiple boards. Working in conjunction with a carrier board, which contains all the I/O and any customization required by the particular avionics application, the COM Express module brings performance and low power to standards-based, very small form factor designs. Broad vendor support makes the design process easier, and designers have access to a well-established ecosystem of resources to manage future product migration.
Flexible I/O and interconnects extend avionics design value
In the COM Express standard, PICMG has different defined pin-outs for one or two 220-pin connectors that are placed next to each other. The positioning of the connectors guarantees extremely simple interchangeability of the three form factors; the connectors themselves are resistant to shock and vibration and offer extraordinarily high bandwidth for high-speed data transmission.
COMs offer significant design value and flexibility, providing chipset I/O to the carrier board via these rugged board-to-board connectors. Broad combinations of I/O are readily available, and need only be brought into the design via the application-specific customization of the carrier board. LAN, SATA, video, audio, multiple USB, or PCI Express ports are all available, and depend simply on the requirements of the end-use application itself. COMs also integrate video processing and display, an important advantage for graphics-heavy imaging and data processing applications often found in avionics systems. The COM Express standard is considered the likely requirement for long-life video support native within the chipset, and enables standard connector access for VGA, LVDS, SDVO, and now DisplayPort, DVI, and HDMI. This avoids the need for added video cards that might be required by other platforms, or borrowing access from CPUs already constrained in space for processor, chipset, and memory.
COM Express is also the first independent module standard prepared for innovative interface technologies such as USB 3.0; new Type 6 and Type 10 pin-outs help ensure long-term protection of deployed systems. COM Express technology now has the ability to handle future developments while retaining the connector concept, technology, and maximum backwards compatibility with the established Types 1 and 2 (Table 1).
Type 6 is based on pin-out Type 2, the most widely adopted COM Express pin-out type to date, but reallocates legacy PCI pins from Type 2 to support the digital display interface and additional PCI Express lanes. This enables a performance jump from devices incorporating earlier pin-out options, and enhances fourth-generation graphics architectures often used in advanced video applications such as surveillance for situational awareness.
The Type 6 pin-out also considers future design options; the pins formerly assigned the IDE interface in pin-out Type 2 are now reserved for future technologies still in development. This gives designers more to work with, including broader native display choices and higher serial bandwidth than previously available. COM Express’ native support for the newest display interfaces also simplifies carrier board design, which reduces time to market and Total Cost of Ownership (TCO) for graphics-intensive military and aerospace applications. PCI Express support for Type 6 is extensive and underscores the trend to migrate from legacy parallel interfaces toward pure serial embedded system designs for higher bandwidth and reduced latency. Military system designers have a smooth transition to next-generation devices via faster drives and peripherals – essential for the rigors of long-term avionics deployments.
Rugged by design
COMs also offer access to extended thermal characteristics “by design” – or through a COM that has been re-engineered and validated for proven functionality in extended-temperature applications. Military and aerospace or industrial temperature ranges are typically -40 °C to +85 °C, with some components offering a subset industrial temperature range of -25 °C to +75 °C. In a “by design” COM, suppliers offer testing of complete systems and individual components to assure that performance withstands specific environmental conditions, which is essential to very small form factor avionics in mission-critical designs that are packed with high-performance features (Figure 2).
COM Express is up to the avionics design challenge
Sophisticated avionics applications offer some of the greatest challenges for designers of rugged, extended temperature systems that are constantly exposed to extreme external and internal conditions such as wide temperature variances, system start-up in low or high temperature, humidity, dust, and other environmental circumstances that can seriously impact performance. These rigorous requirements will only increase as avionics deployments become more complex, for example by integrating more cameras and sensors in surveillance or evolving diverse airborne devices that may include robotics.
It is not practical to simply add more equipment onto an unmanned vehicle, yet demand continues for more sensor capability, or flexibility, to change or update sensor arrays based on specific mission profiles. This increases the necessity for a compact and modular open-standard-based high-performance module or system, and sets the stage for a proven small form factor such as COM Express.
Delivering performance today and positioning OEMs for continued evolution of devices and applications, COM Express modules allow priority design consideration of ruggedness and flexibility. Scalability builds on what the silicon currently enables, and further capitalizes on board-level consistencies and conveniences, such as the ready availability of drivers. Designs can follow the same pin-outs and connector schemes, and ensure a smooth path to performance increases with each new generation of COM – delivering scalable power, performance, temperature, and graphics processing, and creating an optimal platform for avionics applications.
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