RTC Magazine

Computer-on-Modules (COMs) are uniquely positioned for scalable, space-constrained designs—particularly those that benefit both economically and competitively from customization that can last for multiple generations of a given application. Since COMs integrate the complex CPU architecture and circuitry onto a single small form factor module—some as small as 84 mm x 55 mm—designers can focus on using their skills and experience in the development of the application itself. A primary advantage of COMs-based design is that all the application-specific hardware customization is designed into the module’s carrier board rather than the module. So when additional computing power or improved energy efficiency is required by the application, the COM can be quickly and easily replaced with one that meets the appropriate performance and power requirements.

The standards-based module, which works in conjunction with the customized carrier board, connects all the peripherals and I/O in a consistent manner and can be switched out for any number of performance enhancements. The result is a nearly complete computer mounted on a carrier board, a design concept being implemented into a vast array of embedded applications such as POS systems, industrial equipment, medical devices, rail and transportation systems. 

Customization and the transition from generation to generation are simplified with this platform. However, designers need to be aware of pitfalls or design gaps that must be addressed as they port software from one COM to another, or shift from legacy to next-generation COM product families. With some forward thinking and planning for future generations of the device or application, designers can avoid any surprises or “gotchas” that go along with upgrading designs for added features or increased performance.

Avoiding the Gotchas

Planning for scalability across the full range of the COM Express specification may require attention in first-generation designs, including anticipating the need for smaller device size, improved thermal characteristics and increased performance. Overall, important design elements such as pin-out types, module size, software and interface compatibility, and which designs require a new carrier board or updated processor, become critical considerations. To add new functionality to a COMs-based design, implemented controls may be required for native support of specific features such as new display integration, higher performance graphics capabilities and increased security (Table 1).

Cores can be upgraded within a product family (e.g., COM Express module to COM Express module), or the design can be upgraded within the COM specification. Moving from legacy technology such as ETX into more current I/Os and interfaces found in COM Express does not require a core CPU module change, but an actual swap of the COMs technology implemented. These designs do require a new carrier board, although similarities to the ETX layout allow designers to incorporate existing compatible software technology.

Pin-out types must be considered; currently there are five pin-outs defined under the COM Express specification. To maintain the same carrier board with an upgraded COM module, designers must work with the same pin-out with any new module as well. For example, an ETX carrier board is not compatible with XTX modules because of its alternate pin-out definition. Module size may also be an important consideration, particularly with a first-generation design.  If the earliest design allows only enough room for a carrier compatible to the nanoETXexpress (the smallest “ultra” form factor), the application may not be scalable across the specification or able to take advantage of any modules in the compact or basic sizes.  

Features such as native support for VGA or SATA/PATA may require control implemented on either the module or the carrier board if the processor does not offer that feature (i.e., eMenlow).  Depending on the processor/chipset, PCIe may even be required to bring out Ethernet or other features, ultimately reducing the number of available PCIe slots for the carrier board to use with add-ons such as PCIe graphics cards.  

Second-generation Atom technology has impact here as well, with COMs such as the microETXexpress-PV (Figure 1) incorporating the dual-core Intel Atom D510 processor (2x 1.66 GHz). This represents a performance jump (and an upgrade path) from the microETXexpress-SP based on the first-generation, single-core Intel Atom Z5XX series delivering from 1.1 GHz to 1.6 GHZ performance. The microETXexpress-PV also delivers native LVDS and VGA simultaneous graphics support as compared to its predecessor, which requires implementation of a VGA controller on the application-specific carrier board if the feature was needed.

Intel’s 32nm processor technology also has designers looking for upgrade paths. For example, the ETXexpress-AI offers designers greater flexibility due to its 32nm Intel Core i7/Core i5 processor technology, high energy efficiency, wide graphics support, customizable PCI Express configuration and ECC dual-channel RAM to ensure data accuracy. Both computing and high-end graphics performance are improved, enabling a performance jump from the ETXexpress-MC, designed for fourth-generation graphics architectures used in advanced video applications.

The COMs Revolution

In areas where reduction of device size is a key driver, for instance medical embedded design, COMs are leading significant growth as a design platform. Perhaps a diagnostic device once built onto a cart needs to be made even smaller and more portable, such as a battery-powered fist-held device that can be kept with the medical staff moving from patient to patient. COMs are well-suited to evolve designs not only from medium-sized desktop or stationary devices to tablet-size applications and on toward smaller and smaller palm-sized ones—but also provide upgradability within a single product generation. Compute-intensive imaging that previously required a much larger single board computer can now be managed effectively by a high-performance COM such as the ETXexpress-PC. With planning, even smaller footprints can be achieved using microETXexpress-PC modules based on the same chipset and CPU. 

Performance options are scalable, and designers can anticipate that future COMs, such as the recently introduced microETXexpress-XL (Figure 2), will provide even more options for sister devices that demand high resistance to shock and vibration while operating in extreme temperature conditions. Markets such as industrial control and transportation are likely to benefit from these advances, with robust COM Express-compatible modules offering a suitable match for designs that span an incredible range of varied end-use applications and the likelihood of multiple device generations. Train management and wayside systems, automatic piloting, interlocking and control center systems, as well as passenger information, onboard infotainment, tunnel safety and automated digital video surveillance are just some of the compute-intensive, high-availability technologies characterized by extreme conditions, round-the-clock performance and high-speed processing requirements.  

Overall, COMs show continued promise in low-power, ultra-mobile applications that require energy-saving x86 processor performance, high-end graphics, PCI Express and Serial ATA combined with longer battery life. This represents a broad slate of embedded design areas, including handheld devices for medical or multimedia applications, transportation infotainment systems, small mobile data systems and even new applications previously limited by size or power consumption.

The COMs Evolution

A fixture on the embedded landscape for more than ten years now, COMs have come quite a long way in what they bring to the table. The COM Express standard has been critical to the evolution of smaller and smaller modules, at the same time offering the assurance of consistent physical layout, pin assignment and carrier board mounting holes. Currently the standard specifies module sizes in basic ETXexpress (125 mm x 95 mm), extended (155 mm x 110 mm) and compact microETXexpress (95 mm x 95 mm). The compact microETXexpress was driven by more recent 45nm chip technology, along with the newer ultra nanoETXexpress (84 mm x 55 mm), which is expected to be integrated in the PICMG standard shortly (see sidebar “COM Express Extension,” p. 35). 

Further, advanced processing technologies continue to change the game—offering breakthrough improvements in performance delivered and power saved. For instance, the 45nm Intel Atom processor architecture achieves fast performance (with clock speeds between 1.1 GHz and 1.6 GHz) in a sub 5-watt thermal power envelope. It features a power-optimized front side bus (of up to 533 MHz) for faster data transfer, in turn enabling development of energy-saving, high-end graphics devices based on the Intel Atom processor and the Intel System Controller Hub US15W. Modules that integrate Intel Core i7 and 32nm processing advancements deliver even greater design flexibility, using an efficient two-chip solution for better signal integrity and minimized board space, in turn enabling higher performance for smaller, power-constrained portable designs. 

Intel Core i7 benefits such as new display integration, higher performance graphics capabilities and increased security features will continue to drive the COMs development path. Additional “by design” features are available today, such as high reliability in terms of shock and vibration tolerance, and performance in industrial temperature ranges of -40° to +85°C.  As a result, designers are achieving greater performance in their designs, without leaving the safe and proven development path of COMs as an established and future-proof industry standard.

The COM Express specification means design security, guaranteeing manufacturer-independent continuity and consistent availability across the larger range of manufacturing sources. With broad industry adoption among both suppliers and users, COMs enable faster time-to-market, reduced development cost and minimized design risk. The benefits reach into future generations as well—with simplified upgrade paths, scalability and increased application longevity.  

Kontron
Poway, CA.
(888) 294-4558.
[www.kontron.com].