RTC Magazine

Computer-on-Modules (COMs) are proven workhorses—essential building blocks that embedded designers rely on for scalable, space-constrained designs or customization. COMs appeal to designers because they allow them to focus on their core competency of building the application itself, since the application-specific hardware customization is designed into the module’s carrier board rather than the module. For product enhancements throughout a long-term embedded design plan, a standards-based COM module can be quickly and easily replaced with one that meets the appropriate performance and power requirements. This in turn leaves its associated customized carrier board intact, which eliminates additional development time and costs related to redesigns and product evolution.  

Even as the COM-based approach absolutely eases customization and design migration from one generation to the next, the design of the carrier board is not as simple as it appears. An internal base of knowledge of I/O circuitry is essential, as well as extensive expertise in the actual design of the carrier board customized I/O. Furthermore, many times OEMs are dealing with competing objectives—such as dynamic market needs and the corresponding technology demands of a given application—that sometimes work against balancing total project cost and profitability goals.

Choose Value, Performance or Both

Computer-on-Modules benefit designs both economically and competitively by means of customization that spans multiple generations of a particular application. With COMs integrating the complex CPU architecture and circuitry onto a single small form factor module—some as small as 84 mm x 55 mm—designers can concentrate their talents and expertise on the development of the application itself.  

This results in one of the biggest advantages related to COM-based design. Using one carrier board, designers have the opportunity to launch multiple products based on the same design meeting the specific needs and regulations of different geographies. By incorporating modules that offer a range of performance features, a product line ranging from value to high performance could be launched in tandem. Higher end products would simply leverage COMs with higher performance and more advanced features such as security, thermal performance, or graphics processing whereas lower-end designs would deliver necessary performance while limiting which advanced features were activated on the board. Scalability also exists within each design, as the COM is upgradable from generation to generation of a single product.

Teaming COMs and Carriers

A standards-based COM works in conjunction with the customized carrier board, connecting all the peripherals and I/O in a consistent manner. This module can readily be switched out for any number of performance enhancements. The result is a nearly complete computer mounted on a carrier board, a design concept benefitting a vast range of embedded applications. Since all the application-specific hardware customization is designed into the module’s carrier board rather than the module, the COM can be quickly and easily replaced for one that meets new performance and power requirements. This scalability can extend a system platform’s longevity by offering the opportunity for system refreshes over time.

At other times it may make sense to offer an additional system platform with different functionality using a similar carrier board. This largely applies when reduction of device size is a primary driver, for instance in medical embedded design. Perhaps a diagnostic device previously built into a stationary device needs to be even smaller on a cart with medical staff moving from patient to patient. COMs support evolution to smaller and smaller layouts—but also afford upgradability within a single product generation. Compute-intensive imaging that once required a larger single computer-on-module can now be run effectively by a high-performance COM. With planning, even smaller footprints can be attained using modules based on the same chipset, CPU family and pin-out. By using the smaller module and developing a new, smaller carrier board, the OEM can offer similar performance in a reduced system size to meet the new requirements.

Planning for Upgradability

So is increasing performance as simple as replacing one COM with another on the same carrier board? It can be, but designers really must consider several key areas when upgrading a COM-based design. Pin-out, module size and module family are crucial considerations, as well as software compatibility, evolving thermal characteristics, and overall power and performance. 

Cores can be upgraded within a product family (e.g., COM Express module to COM Express module). They can also be upgraded within the COM specification. Migrating from legacy technology such as ETX to the more current I/Os and interfaces inherent in COM Express does not involve a core CPU module modification, but an actual swap of the COM technology employed. These designs do require a new carrier board, although similarities to the ETX layout permit designers to incorporate existing compatible software technology.

Pin-out types must be taken into account, and there are currently five pin-outs defined under the COM Express specification. To retain the same carrier board with an upgraded COM module, designers must maintain the same pin-out type with any new module. For instance, an ETX carrier board is not compatible with COM Express modules due to its alternate pin-out definition. Module size may also be a key consideration, primarily with a first generation design. If the initial design allows only enough space for a carrier compatible to the COM Express Mini, then the application is scalable to new modules in the same size. For example, one can migrate from COMe-mSP to COMe-mTT10 or COMe-mCT10, which are all the same size and have compatible pin-out types. However, it will not be possible to take advantage of any higher performance modules in the compact or basic sizes, which use different pin-out types. A comparison between the Type 2 and Type 6 pin-outs is shown in Figure 1.

In order to effectively plan for scalability across the full range of the COM Express specification, designers must carefully address performance challenges of first generation designs. This includes anticipating requirements for shrinking device size, enhancing thermal characteristics and improving processing performance. Overall, important design elements such as pin-out types, module size, software and interface compatibility, along with determining which designs require a new carrier board or updated processor, become crucial factors. To add new functionality to a COM-based design, controls may be required for native support of certain features such as new display integration, higher graphics performance capabilities and improved security.

Native support for VGA or SATA/PATA may require that control be implemented on either the module or the carrier board if the processor does not offer that feature. Depending on the features of the processor or chipset, PCIe may even be required to obtain Ethernet or other features, in due course reducing the number of available PCIe slots the carrier board may utilize with add-ons such as PCIe graphics cards.  

Making It All Work

Leveraging both starter kits and evaluation boards is imperative to successful COMs-based design. Commonly packaged in a single case, these allow a head start on validating software, testing performance and features, and lining up connectors and jacks to assure the fastest time-to-market. For example, the Kontron COM Express Reference Carrier Type 6 is specifically designed for the development of innovative small form factor (SFF) applications and supports all future-oriented interfaces required in small and portable applications (Figure 2). OEMs can leverage such a reference carrier board in the Mini-ITX form factor, which accelerates application development.  It can also be used off-the-shelf paired with the broad ecosystem of Mini-ITX accessories to reduce time-to-market and development cost.

SIM card support and smart battery support enable flexibility for OEMs developing embedded products and systems. The broad range of graphic interfaces found in such reference carrier boards includes LVDS, DDI (DisplayPort/HDMI/DVI) and VGA (via DVI-I), and allows developers to connect any embedded display type without the need for additional components. High-speed serial interfaces including USB 3.0 allow connection of the most modern peripheral components to facilitate building small and portable systems with commercially available standard components. 

BIOS adjustments to the computer-on-module are possible as well to enable or disable key features such as pre-validated Intel vPro technologies and other adjustments, such as timers or desktop splash screen additions, to customize functionality to meet specific needs of the OEM platform. The adjustments can be done by the OEM developer, or by development partners like Kontron. If volumes are high, a custom SKU of the computer-on-module may be more practical for OEM needs.

Cooling solutions and battery support vary based on the module and the chassis design. There are multiple options of active and passive heat dissipation methods for the computer-on-modules so the best option may be selected to meet the platform needs. Each is fully validated to function with the computer-on-module. For example, an active heat sink may be used on basic modules, since it can dissipate up to 20 watts TDP of the CPU for the new COMe-bIP2/6, using the Intel Core i7 processor. A passive heat spreader or an active cooler with a fan may be used on a lower wattage compact module such as the new COMe-cCT6 with the Intel Atom N2800. 

Once the module is connected to the carrier board and other elements such as drives are added to the system design, the thermal situation needs to be analyzed and supported via the chassis design. This can be simulated so decisions can be made early in the system design process. Processors that draw lower currents, such the Intel Atom family, are well suited for fanless chassis operation as long as other accessories in the system and other factors such as altitude and ambient temperature do not raise the system operating temperature significantly. For higher wattage planned system configurations to achieve fanless operation, special chassis conduction cooling, by either chassis heat pipe, cold plate or liquid cooling may be required. 

With the lower processing wattages of the newer Atom processors, it is now possible to use batteries for system power. Newer Type 10 carrier boards for Mini COM Express computer-on-modules may support RTC battery operation, allowing OEMs to test this capability during evaluation.  

Maximizing Product Platform Lifecycles

The COM Express standard has been critical to the evolution of smaller and smaller modules, while at the same time offering the assurance of consistent physical layout, pin assignment and carrier board mounting holes. Further, advanced processing technologies continue to drive the design landscape—offering breakthrough improvements in performance delivered and power saved. For instance, there are already a range of value- and performance-based modules using third generation Intel Core processors (Figure 3).

Applications with tight thermal restrictions in medical, digital signage, infotainment, point of sale and unmanned aerospace and defense applications also benefit from the up to 40 percent increased performance per watt ratio of this new benchmark processor series. For example, a medical or transportation entertainment design needing high-end imaging that used the OMe-bAI6 module could upgrade to the COMe-bIP6 module, improving both processing and thermal performance while using the same Type 6 carrier board that enabled earlier product generations.

Modules that integrate Intel Core i7 and 22nm processing advancements deliver greater design flexibility. By using an efficient two-chip solution for better signal integrity and minimized board space, higher performance is enabled for smaller, power-hungry portable designs. With 22nm architectures, performance-per-watt is superb. Such a solution experiences no performance hits and results in enhanced I/O capabilities. The benefits of the third generation Intel Core i7 architecture, such as new display integration, higher graphics performance capabilities and improved security features, will continue to drive the course of COMs development. As a result, designers are attaining greater performance in their designs without abandoning the safe and proven development path of COMs as an established and future-proof industry standard.

With some forward planning in addressing future generations of the device or application, designers can not only avoid surprises but also maximize their product platforms for long-term performance and market leadership. Increasing performance, reducing device size and adding features such as improved graphics and security can be achieved with existing carrier board designs and a well-planned approach that leverages processor advancements and upgradable COMs.  

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