Small Form Factor SBCs and COMs

Making Smart Design Choices in the Growing World of Connected, Intelligent Devices

Small form factor design is in heavy demand, as the Internet of Things pushes intelligent systems further out to the network edge. System developers strive for reliable, connected platforms that deliver right-sized performance and help them beat competitors to market.


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Small form factor systems have a growing role in the connected world. Massive amounts of sensor data is being collected and shared by an exploding group of small but powerful systems, enabling a range of new applications and deployments fueled by the Internet of Things (IoT). Creative and purposeful system design is at the heart of this phenomenon, with developers balancing current performance with the need to keep systems poised for further advancements in data sharing and analytics. For designers, choosing the right design platform is the essential first step in getting to market quickly and gaining a competitive performance edge in connected, embedded arenas.

Developers have a broad range of good options when it comes to choosing a platform. Sticking to what you know creates specialists, and often times the choice simply comes down to personal preference based on experience with a specific platform. But when the mission is to develop the best solution with the latest technology, the decision becomes more complex and challenging—driving developers to examine specific criteria to determine their design plan. Price, long-term performance and I/O are top among concerns that drive the decision process.

Designers often avoid a platform move, citing concerns about validation testing, troubleshooting and initiating a longer than necessary cycle of product development. Legacy concerns, upgrading a system, or tying a new system into an existing solution can also override many platform options, leading designers to stay within their comfort zone in an existing platform.

If there is no overriding argument to stay with a given platform, then these factors are absent and there is much more of a blank slate in terms of design options. Developers narrow the field by considering price versus performance and I/O requirements in context—weighing these design considerations against environmental demands and long-term product planning (Figure 1). The resulting design plan considers the trade-offs, challenges and benefits.

Figure 1
Figure 1: Performance, flexibility and configurability all play important roles in helping designers choose a small form factor platform.

Evaluating I/O Flexibility

What kind and how much I/O does the system need? If this solution requires standard PC-like functionality such as USB, network connections and wireless access, then a motherboard solution with common I/O options may nicely balance cost and performance. Consider a motherboard in the miniITX or picoITX form factor, which is designed similarly to the motherboard of a personal computer. All components are on a single board, including the built-in processor. All I/O is defined and tied to the board in a standard manner; designers work with designated I/O choices and there are limited options for expansion, as typically an mPCIe slot may be available. These motherboards use commercial connectors and typical commercial components, industrial grade but not suited for extreme rugged deployment. 

All this equates to a relative reduction in performance and a less flexible solution—both of which can be perfectly acceptable depending on your design strategy. Less flexible solutions typically have more volume availability and therefore less cost. If the performance is suitable, designers can win with the price versus performance trade-off enabled by standard motherboards.

Industrial control applications have successfully used this platform as the compute system inside machine control or monitoring solutions. It’s typically deployed indoors in a fixed setting such as a cabinet or stationary machine on a factory floor. These settings are somewhat protected, maintain a consistent temperature, and do not stress system cables with motion or mobility. In these applications, commercial connectors enable further value, as there is no need for the additional cost of rugged, locking connectors. Using motherboard-based designs, industrial system developers can deliver cost-effective performance in a standard box-PC system. Costs are kept down and the designer can focus on distinguishing the solution with a high-performance software application that adds unique value to the end-user.

Achieving Flexibility with 3U SBCs

How flexible does the design need to be, both for performance today and in future product generations? 3U SBCs offer a flexible alternative, which is an advantage when designs warrant multiple processors and significantly more I/O. 3U boards are based on the Eurocard mechanical standard and plug into a passive backplane. Multiple boards can be plugged into the backplane depending on the system platform, which can be CompactPCI, CompactPCI Serial, VPX and others. 

In contrast to motherboard solutions, 3U systems offer greater reliability for more mission-critical applications. When a motherboard fails, there is no redundancy and the system fails until a full replacement board is installed. When a 3U SBC fails, it can simply be replaced while the others in the backplane ensure continued performance. As a result, mean time to repair is much faster with a 3U SBC solution with hot-swap features. Boards are more rugged, and the system is expandable and highly customizable. Designers can mix and match boards and I/O to create a system that handles very specialized processing in a cost-effective manner, for example, connecting one high-performance processor with multiple I/O boards.

Considering Performance Upgrades

What is the performance upgrade path for the design? Standard motherboards like miniITX and picoITX don’t offer an option for processor upgrade; the board itself would need to be swapped out in order to take advantage of processor advances. 3U systems are significantly more flexible by virtue of the number of backplane slots and hot-swap functions, although a board would still need to be swapped. COM Express Computer-on-Modules (COMs) offer flexibility in terms of enabling cost-effective processor advancements, particularly in systems that require application customization.

This is because a COM is considered a nearly complete computer that is mounted on a carrier board. The carrier board contains the customization, and the module can be switched out without affecting the customization. This architecture positions systems to accept a broad range of processing performance options. Performance advancements require only a shift to the latest processor module option, ensuring a long lifecycle to customized systems.

COM Express offers some of the smallest form factors available for connected systems, offering sizes excellent for edge devices such as field sensors in fixed or mobile deployments. Packing high performance in small spaces, the standard’s smallest form factor is the mini, about the size of a credit card at 55 x 84 mm. With options for extremely low power consumption, COMs are well-suited to mobile, battery-powered and above all, inexpensive applications (Figure 2). These are growing challenges as broadly distributed IoT deployments continue to extend into new markets and creative new applications. COMs’ wide range power input (from 5V to 14V) makes them an ideal fit for small form factor connected applications, especially when considered in tandem with their ability to handle extreme environmental conditions and temperature ranges from -40° to +85°C.

Figure 2
Figure 2: Kontron’s COMe-cHL6 capitalizes on 4th generation Intel Core processor technology, enabling compact and rugged fanless Computer-on-Module options.

New modules in the compact form factor (95 x 95 mm) are equipped with the ULT versions of the fourth generation Intel Core i7/i5/i3 and Intel Celeron processors, formerly codenamed “Haswell.” ULT stands for ultra-low TDP, which limits the power consumption tailored for fanless and fully enclosed system designs. The modules also cater to the most robust and maintenance-free system designs in the high-performance class of embedded systems, and consequently help engineers to reduce the systems’ bill of materials as well as the customers’ total cost of ownership.

Application areas can be found in all the performance-hungry but power-restricted, multi-touch, multi-display systems such as HMIs in automation, medical imaging, digital signage and point of sale, as well as surveillance and security. The modules also address the fast-growing, industrial-grade tablet PC market for various industries including logistics, retail and manufacturing.

Customizable I/O challenges are well-handled by COMs-based systems as well. If the end use is more specialized, for instance in a medical environment, a special I/O interface may require conversion over a circuit that is not readily available on the motherboard solution. COM-based systems enter the picture as a contender here. The specialized part of the design’s schematic could exist on the COM’s carrier board with the COM Express module readily handling the rest of the system.

COMs provide the chipset I/O to the carrier board via rugged board-to-board connectors. Associating module I/O designs onto the carrier board such as mPCI or mPCIe then allow a broad combination of I/O options that 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 connected IoT systems. 

Ecosystem Impact

In a given application and market, what I/O is already available and in what form factor? Broad vendor support makes the design process easier, and with each of these well-established platforms, designers have access to a robust ecosystem of resources to manage future product migration. Strategic decisions here add significant market value. When protecting your intellectual property (IP) is a concern, it makes good design sense to build on either a COM or motherboard platform, depending on the other factors at play. Leveraging ecosystem IP quickly moves a design toward a 3U platform.

For example, 3U form factor designers have ready access to a large number of specialized I/O cards developed for certain markets. Developers can quickly leverage I/O that is specialized but cost-effective as an off-the-shelf solution. A high-performance compute system using multiple processor boards with integrated radar or communication I/O illustrates this, creating a system-level box well-suited to the flexibility and reliability of a 3U platform with a vast I/O catalog available on the market.

In contrast, consider an interactive solution where the I/O is essentially the touchscreen. Developing an integrated interface like this, or perhaps a panel or display, logically drives a design to COM Express. Developers would not want to lock into ready-made I/O for their carrier board because of the potential for limitation on a customized carrier board intended to endure for multiple product generations.

Designers have many excellent processing options across the range of small form factor platforms. Each market continues to mature and expand, and the existing ecosystem can add tremendous value in determining a design plan. Motherboards, 3U platforms and COMs each play an important role in advancing connected, embedded systems that create and support the Internet of Things.

Price, performance and I/O considerations for each of these platforms are top issues for designers to examine as they begin the design process—along with the need to address rugged deployments and plan for future product generations. Motherboards may fit the need for defined performance; 3U offers maximum flexibility and reliability, and COMs enable long-term flexibility for customized designs. Strategic trade-offs in primary design considerations enable designers to get to market quickly, delivering right-sized performance for the application at hand.

Kontron, Poway, CA
(888) 294-4558