Designing for scalability and migration with small form factors
December 01, 2011
The open scalability of COMs provides smooth navigation to the next generation on the device roadmap.
Scalability brings different advantages to different embedded applications. Performance, interoperability, power consumption, temperature thresholds, graphics processing – all are potential factors in determining if a scalable platform is required as a migration path for next-generation applications.
In the scalability equation, priority attention depends on the goal of the design and its embedded environment. Embedded designers must look beyond their current designs and think strategically when selecting platforms with appropriate migration paths for longevity, feature set, and performance. At the same time, designers must get products to market quickly, fueling the need to minimize development time through proven, standards-based embedded platforms with reusable design layouts.
Small form factor COTS platforms have steadily filled OEMs’ scalability and migration path needs, supporting a wide variety of CPU cores that deliver ever-increasing computing power and improved performance across a range of applications and markets. In the past decade, Computers-On-Modules (COMs) have made the design process easier, offering standards-based solutions that have broad vendor support.
With COMs, designers have a broad ecosystem of resources to manage migration, as well as essential design flexibility to add new features with custom carrier boards. An example of a small form factor that continues to offer designers long-term options is COM Express, which has consistently provided technology advancements in performance, low power, superior graphics processing, and extended temperature operation.
Migrating legacy designs to COM Express
Because many small form factor designs originated on the ETX 3.0 platform, designers must decide to either stick with ETX or switch to COM Express to future-proof designs and incorporate new features and performance. If the design jumps to COM Express, how are product upgrades handled within that standard?
Remaining within legacy ETX is an option, and modules using the same pin-out can be easily swapped out for improved performance. Designs can also be upgraded within the COM specification, moving from legacy ETX technology to support current I/O and interfaces found in COM Express. This type of migration requires not just a core CPU module change, but also a swap of the COMs technology implemented and a new carrier board. This is because COM Express achieves next-generation performance with a greater number of pins in fewer connectors than ETX. However, the module layouts are similar, enabling designers to leverage existing compatible software technology.
Once a design has migrated to COM Express, cores can also be upgraded from one COM Express module to another. Complexity depends on the extent of the migration. Drivers are the primary challenge, although the design might also require pin-out adjustments on the carrier board if modules are adapted from one pin-out to the next, for example, from Type 2 to Type 6 or Type 1 to Type 10.
Moving to COM Express is appropriate for products that benefit from the availability of PCI Express (PCIe). The two-connector layout of COM Express requires a new carrier board, and the resulting design is poised for advanced I/O interfaces and ongoing performance enhancements such as tolerance to extended temperature ranges. Although pin assignments are standard as defined by COM Express, the carrier board design or selected chipset can affect the number of available PCI lanes.
Customization is managed within the carrier board, offering another significant advantage when scaling a design. Once customization is resolved within the initial design, it can endure for multiple generations, even as various CPU cores are swapped to extend features and performance. As a result, COM Express can help scale devices not only from generation to generation, but also within a single generation.
This level of adaptability allows designers to integrate benefits of new technologies and processor advances, while at the same time preserving customization investments, avoiding development risk, and speeding time to market. Scalability is manageable with a variety of support resources, maintaining a consistent footprint and pin-out schemes across vendors.
Scaling performance within module families
Next-generation COM Express designs can be simplified by moving from one module to the next within the same family – upgrading to a faster CPU or an alternate CPU and chipset platform. For example, many designs were developed using the Kontron ETXexpress-MC, a COM Express pin-out Type 2-compliant module supporting fast dual-channel memory up to 4 GB via two 533 MHz or 667 MHZ DDR2 SODIMM sockets. The ETXexpress-MC is built around the Intel Core 2 Duo processor (up to 2.2 GHz) and uses Intel’s 965GM Express Chipset, part of the fourth generation of Intel’s Centrino notebook platform. Although this module offers optimized graphics and power efficiency, an evolving application might require more functionality.
Following the same pin-out and connectors, the Kontron ETXexpress-AI (Figure 1) can be implemented as an upgrade. The ETXexpress-AI moves performance and functionality forward through its Intel 32 nm processing architectures and Intel Core i7 features. Designers can integrate 1x PCIe Gen 2 graphics, which are also configurable as 2x PCIe x8, 6x PCIe x1, 4x SATA, 1x PATA, 8x USB 2.0, GbE, dual-channel LVDS, VGA, and Intel High Definition Audio. Furthermore, designers can incorporate legacy non-PCIe-compliant components via the integrated PCI 2.3 interfaces.
Scaling to improve power and temperature characteristics
Increasing demand for ruggedness and reliability has driven the need for systems validated to perform in extended temperature environments. The least strenuous thermal performance occurs in the commercial temperature range of 0 °C to +60 °C. Temperature ranges for industrial applications are typically -40 °C to +85 °C, with some components offering a subset industrial temperature range of -25 °C to +75 °C. Testing of complete systems and individual components assures OEMs that performance will withstand specific environmental conditions.
COMs can speed that process, enabling designers to upgrade cores from commercial temperature requirements to industrial thermal performance. For an example of thermal scaling, consider a medical diagnostic device that upgrades from the commercial temperature microETXexpress-SP to microETXexpress-XL (see Figure 2). The device might be stationary and always plugged in so it resides in a larger space with greater airflow, or it was developed to withstand greater heat during operation. Or perhaps it was originally portable, but now needs to be ultra-portable for use by emergency personnel. Leading the market with a smaller, more portable version of the device will drive OEMs to devote design resources to reducing power usage and temperature thresholds.
Enabling sophisticated graphics performance
Five pin-outs originally defined by the COM Express standard provided designers a well-established foundation for signal assignment and design layout. PICMG’s recent addition of the Type 6 pin-out to the COM Express standard opens up a new world of graphics-based applications with dramatically extended graphics processing and functionality. Pin-out Type 6 (essentially based on Type 2, the most widely adopted COM Express pin-out type to date) capitalizes on the expanded graphics possibilities enabled by new processor families. Legacy PCI pins have been reallocated to support a digital display interface and add PCI Express lanes.
Graphics performance is a priority improvement for many applications, as more and more industrial environments rely on video and high-resolution imaging. Designers can use the same approach in enhancing these features, scaling from module to module for improved graphics performance.
Forward thinking with COMs
Minimizing engineering resources along with reducing risks and development time are key design drivers for the industrial market, fueling healthy demand for scalable COTS-based platforms. COMs and specifically COM Express answer these needs with unique advantages in both longevity and performance. Scalable for power, performance, temperature, and graphics processing, COMs deliver the levels of performance needed today and position OEMs for continued evolution of devices and applications.
Scalability builds on what the silicon enables, capitalizing on board-level consistencies and conveniences such as ready availability of drivers. Designs can follow the same pin-outs and connector schemes while maintaining a smooth path to improved performance with each new generation of COM.