Small form-factor boards continue to evolve to meet the increasing demands of embedded systems.
It's well-known that no universal computing solution exists that satisfies all the unique system requirements of today's varied embedded applications. As personal and industrial computers continue to raise the bar for users, users expect their off-the-shelf embedded systems to operate at a similar performance level. Achieving this nirvana for the end user of an embedded system is daunting for the embedded system designer who now faces power-management issues in addition to new mechanical, thermal, and electrical considerations when designing a physically smaller system. Reducing a system's size without compromising performance is no small achievement; it's a good thing the potential rewards aren't small either.
While many challenges have yet to be tackled, one issue is slowly remedying itself over time–board size continues to shrink, while performance either maintains a certain level or increases. If you look at the history of embedded single-board computers (SBCs), they've gone from very large to very small over the last 25 years. Although those “very large” units still exist, they are few and far between, replaced by much smaller and more efficient models.
For example, the stackable PC/104 boards can handle the applications that a few years ago required much more space. In most cases, size reductions come thanks to the evolution of just about every technology on the board, including the memory, the processor, and the I/O. Essentially, they're all smaller and perform better.
Small form-factor boards have provided much-needed relief to embedded system designers by letting them focus their efforts on their core competencies, helping to reduce project costs and time to market. As a result, the demand for these off-the-shelf small form-factor boards continues to grow rapidly in the embedded space. Today, small form-factor boards are available to fit the unique requirements of almost every embedded application with more than 20 alternatives on the market and new offerings consistently looming on the horizon.
With so many options and new standards emerging, designers can find it difficult to quickly determine which board will best meet their evolving application needs. Designers have the option to develop full custom mother boards, use standard SBCs in various sizes with add-ons and a backplane, and now with highly integrated CPU modules paired with customizable carrier boards, the latest advances coming in the form of ETX and COM Express. Each option has its advantages, which we'll discuss here.
Computer-on-a-module (COM) is suited for a broad range of embedded applications, including those where other form factors, such as add-on cards, can't be used. Expanding and customizing the system is implemented on an application-specific carrier board. Together, the COM and carrier board deliver the functionality of an SBC. As the COM approach gained popularity, the need for standardization became more evident to provide designers with modular, off-the-shelf building blocks.
To answer that need, the ETX Industrial Group developed the Embedded Technology eXtended (ETX) standard in 2000 to provide an open standard to meet the needs of embedded industrial applications with PCI and ISA. ETX modules are compact (95 by 114 by 12mm), highly integrated COMs and offer a number of advantages including PC functionality, low cost, reliable connectors, and simple upgradeability and scalability.
As technology has evolved, the ETX standard has undergone further development in scalability and performance. The latest ETX 3.0 specification offers all of the benefits of the original ETX standard while adding in 2x serial ATA connectors without changing any of the ETX pins, making new modules 100% pin-to-pin compatible with previous versions. This ensures long-term support for the vast number of embedded applications based on these already highly integrated COMs including medical, gaming and entertainment, military, and aerospace.
X-board, another popular architecture, closes the gap between the PC-only DIMM-PC and the full-featured ETX modules. About the size of a business card (68 by 49mm), X-board provides the essential modern interfaces needed for power-efficient processor modules without performance compromises. Despite its compact size, this embedded module offers the highest graphics performance and connectivity interfaces needed by advanced applications.
X-board modules combine low power consumption with fast boot time to serve various space-constrained applications, including test and measurement, diagnostics, medical, automotive, industrial automation, and point-of-sale/point-of-information (POS/POI) systems. In addition, because X-board supports a wide range of interfaces on a smaller COM footprint, system developers can develop easily add features such as integrated graphics, Ethernet, USB, and audio.
High-end applications that require high performance need the computing power provided by the new COM Express open standard, which is under the control of PICMG. An example of a COM Express board can be seen in Figure 1. Developers look to COM Express solutions to replace PCI-X and AGP with PCI Express, replace parallel ATA with serial ATA, or to supply a bridge between legacy and legacy-free functions by incorporating optional PCI and IDE interfaces. By providing a new level of form, fit, and function, COM Express modules can help minimize current and future design risks.
SBCs: Increased design flexibility
Small form-factor SBCs have become increasingly important in embedded environments. SBCs can be as simple or as complex as a particular application demands. While all SBCs are built using similar standards, different technologies can be included, such as video capability, Ethernet access functionality, and digital computer technologies to meet the needs of a particular application. Specialized features, such as a watchdog timer can significantly increase the functionality for industrial applications.
PC/104 has been a popular form factor for use in environments that require rugged hardware and high reliability where repair or replacement may not be possible. Space constraints and suitability for low-power applications have created a niche for PC/104 in applications that don't need game-quality graphics processing. Military, aerospace, and medical customers are especially interested in PC/104 systems for signal-, image-, and data-processing applications, in particular with real-time processing and data transfer.
Because it can be expanded with additional I/O sockets through its unique stacking bus using reliable on-board pins, multiple modules can be added to a PC/104 system without the burden of backplanes or card cages. The design also enables PC/104-based SBCs to work well in rugged environments because of its tremendous shock and vibration tolerance and wider operating temperature range. Another advantage afforded by PC/104-based SBCs is the wealth of expansion cards available which increases design flexibility and reduces time-to-market.
The Embedded Compact eXtended (ECX) form factor addresses the needs for embedded systems that require features and performance comparable with desktop platforms, while taking space and thermal constraints into consideration. ECX embedded motherboards measure 105 by 146mm. This form factor combines real-estate management, the low-power characteristics of the Intel Pentium M processor, fanless thermal management, and support for multiple interfaces to meet the requirements of vehicle infotainment systems, medical equipment, industrial automation, and human-machine interface devices.
Embedded motherboards provide a reliable and robust option that's expandable, interchangeable, and customizable for long-term availability. The Advanced Technology Extended (ATX) form factor, created by Intel in 1995, was defined to address ease of use, support for current and future I/O and processor technologies, and the need for high performance. A full-size ATX board is 305 by 244 mm, as shown in Figure 2. The range of applications for embedded ATX boards includes 19-in. rack-mount systems, POS/POI applications, the games and infotainment market, measurement engineering solutions, and banking. However, they're also found in classic industrial environments or applications that demand high graphics performance, such as medical imaging processing. The combination of versatility, compactness, and good air flow make the 4U size the most common platform for industrial rack-mount systems.
Mini-ITX, developed by VIA Technologies, is another motherboard form factor. With similar advantages to ATX, Mini-ITX is significantly smaller, measuring in at 170 by 170mm, as seen in Figure 3. Because of its small dimensions, it's become the popular embedded computing choice for consumer devices with compact housings. The Mini-ITX form factor, originally developed by VIA, can be passively cooled due to their low power consumption, which makes them useful for kiosks, gaming, video security, and digital entertainment devices.
Embedded systems developers will continue to be plagued with competitive pressures to provide more features and improved platform-management capabilities. This often requires tradeoffs between performance, space, and power. To further complicate matters, they're often faced with shrinking form factors, eliminating the option to increase footprint to make room for more power or performance.
The good news is that advances and availability of solid multicore processing platforms have proven to offer higher compute performance, reduced chip count, and a lower bill-of-materials, with drastically reduced power consumption. Intel's multicore architecture provides a powerful and power-efficient platform that delivers increased performance-per-watt to provide greater processing in a smaller area, while reducing the associated costs and risks of implementing new technologies.
Because dual-core processors provide two complete execution cores instead of one, each core has an independent interface to the front-side bus as well as its own cache. This allows the operating system with sufficient resources to handle intensive tasks in parallel, which provides a noticeable improvement to multitasking. Thanks to this parallel concept (which was previously available only on expensive parallel computers), dual-core processors make it possible to distribute tasks to several computer units, thereby duplicating performance. The power dissipation of a dual-core processor is virtually unchanged in comparison to the traditional parallel computer.
Today, multicore processing is being integrated into a number of standards-based modular, off-the-shelf form factors for embedded applications. While the current generation consists of dual-core processors, multicore processors are the goal as technology shrinks and there's more real-estate available on the die. Quad processors are only the beginning. Chipmakers will continue to push for greater performance, using a combination of improvements in circuitry and more advanced manufacturing technologies.
Christine Van De Graaf is the product marketing manager for Kontron America's Embedded Modules Div. Christine has more than seven years of experience working in the embedded computing technology industry and holds an MBA in marketing management from California State University, East Bay, Hayward, CA. She can be reached at .