Advances in Small Form Factors
Embedded Form Factors Harness Emerging Technologies to Enable Wireless Systems
Developments in low-power processors, highly integrated peripherals and new interconnects are shrinking the size and power consumption of modules to allow their deployment in wireless network applications.
JASON KRUEGER, VERSALOGIC
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Wireless connectivity is merging with technological advancements in silicon, signaling, mass storage and software to meet the high-performance, ultra-low-power requirements for next-generation wireless systems. Embedded form factors, seeking to utilize these developing technologies to the best advantage of system designers, continue to evolve by facilitating emerging standards and providing enhanced capabilities while simultaneously reducing form factor footprints. As wireless connectivity becomes increasingly ubiquitous, the volume of embedded systems that utilize wireless is expanding, thereby perpetuating the demand for higher processing power with minimal power draw and size.
Embedded computing systems have long been tethered by wires to a stable infrastructure providing myriad connectivity options and a continuous source of power. For applications where the data is beyond the infrastructure, the solution has often been to build the infrastructure out to the data. Though this approach is feasible in locations where a wired infrastructure exists and the distance to be wired is relatively short, wired connectivity quickly becomes prohibitively expensive as the distance to be wired increases; furthermore, building out infrastructure is an entirely improbable solution in situations where there is no established infrastructure to begin with.
The solution to the limitations imposed by wires is simple—remove the wires. Though this dream of wireless connectivity has existed since the first network packet was sent over a wire, the technology required to facilitate reliable, high-bandwidth, secure data transmission has only recently emerged as a truly viable solution. The continuing evolution and adoption of wireless protocols, including Wi-Fi, WiMax, CDMA, UMTS, LTE, Zigbee and Bluetooth, along with free worldwide access to Global Positioning System (GPS) data, has unleashed an explosion of wireless consumer devices, including smartphones, mobile Internet devices (MIDs), e-books, portable media players and navigation systems. The success of these products has proven the potential for wireless applications while simultaneously fueling the expansion of the infrastructure necessary to sustain them. This has in turn opened the door for sophisticated wireless applications in the embedded systems space that take advantage of increased processing power and expanded system capabilities to revolutionize both existing and emerging embedded applications.
The freedom afforded by wireless carries with it inherent design restrictions. Lacking a constant supply of wired grid power, wireless systems typically rely on batteries. Faced with a scarcity of power, stringent control of power consumption is no longer an option but a necessity. Size is also a major design factor, as smaller sizes afford greater mobility. Support for standard interfaces and peripherals is also required to facilitate design implementation, speed time-to-market and keep system costs to a minimum. Wireless systems must also communicate over standard networking protocols and utilize advanced data compression and security functions to minimize bandwidth while maximizing data integrity and security. Wireless systems are often deployed in demanding environments subject to extreme physical and environmental stresses, which necessitates the need for ruggedized solutions with unquestioned reliability, especially in the case of remote applications.
RISC architectures, including ARM and PowerPC, have been the preferred choice for wireless embedded devices due to their ultra-low power consumption and superior performance-to-cost ratio in the light of application requirements and production volume. Success naturally breeds competition. While RISC technology continues to drive incremental increases in processor performance, CISC architectures (primarily x86), have been aggressively moving into the wireless embedded systems space through radical decreases in power consumption and package size.
Intel and VIA have been aggressively transitioning x86 technology into the wireless embedded systems space. Initially targeted at the netbook market, then at even smaller, lower-power nettop applications, x86 technology continues to find its way into smaller and smaller embedded applications.
The second-generation Atom Z5xx processor series (Figure 1) illustrates Intel’s commitment to the exacting needs of next-generation embedded systems. Optimized for low power, thermally constrained, fanless, small form factor (SFF) solutions, the Atom Z5xx series offers system designers a true embedded processor solution with processing performance up to 1.6 GHz, extended temperature operation (-40° to +85°C) and long life-cycle manufacturing support. The Atom Z5xx, along with the System Controller Hub (SCH) US15WP(T), provide the processing performance required to deliver next-generation wireless applications incorporating advanced graphics, display, video and audio capabilities, while support for PCI Express (PCIe), USB 2.0, SMBus, I2C, LPC, IDE (PATA) and GPIO provide a wealth of I/O options to support diverse system applications. Advanced power management capabilities enable power to be removed from the processor core and caches while minimizing leakage to significantly reduce idle power.
SUMIT-ISM SBC featuring Intel Atom Z530P processor, US15WP chipset, SUMIT-AB connector pair, and an IDE Disk on Module (DOM) socket.
Intel is pushing deeper into the wireless embedded systems space as it transitions its System on Chip (SoC) designs to an Atom processor core, providing designers with a broad array of purpose-built processors that share a common core, yet have differentiating features that can be mapped to system requirements for speed, power and temperature range. SoCs further minimize space by combining typical two- and three-chip solutions into a single integrated chip. Originally targeted at MIDs, the addition of Intel QuickAssist Technology will appeal to wireless applications through the acceleration of cryptographic and packet processing to facilitate virtual private network (VPN) gateways, firewalls and Unified Threat Management (UTM).
Further size and power reductions to the x86 architecture will continue to be achieved by building on the success of 45nm process technology, with the promise of 32nm process technology looming just over the horizon.
Interconnects and Storage
As silicon technology advances to increase the amount of processing power available to embedded systems, so does the sheer amount of data that needs to flow in and out of these systems. Multiple simultaneous inputs (GPS, video cameras, microphones, sensors, accelerometers, etc.) and outputs (wireless data transmission), along with a rich user interface (high-definition video and audio), combine to put demanding I/O throughput requirements on wireless embedded systems. To meet these needs, advanced I/O connectors are emerging that offer an array of both high- and low-speed signals to meet the diverse needs of wireless embedded systems. Robust signal support is required, typically including PCI Express (PCIe), ExpressCard, USB 2.0, SMBus, I2C and LPC, as well as control and power management signals.
Additionally, interconnects must be ruggedized for high shock and vibration environments. Smaller connector heights enable denser designs, further reducing the overall system volume. Finally, interconnects must be low cost in order to be viable for original equipment manufacturers (OEMs) in production quantities. Several new interconnect standards have emerged to meet these demands for wireless embedded systems. Some connectors, such as MXM, have been adapted to the embedded space after having proven themselves in the notebook sector. Others, such as Stackable Unified Interconnect Technology (SUMIT) from the Small Form Factor Special Interest Group (SFF-SIG), have been built from the ground up to meet the exacting needs of embedded systems development.
Wireless embedded systems typically use a solid-state drive (SSD) for mass storage. Compared to hard disk drives, SSDs offer substantial power savings. Furthermore, as SSDs have no moving parts, they are less susceptible to the effects of shock and vibration. Secure latching connectors further increase reliability in mission-critical applications. SSD capacities are continually expanding, while extended temperature and conformal coating options are emerging to satisfy the needs of demanding environments. SSDs can be interfaced via parallel ATA (PATA), serial ATA (SATA), USB or PCIe, offering system designers the ability to target their system throughput requirements. CompactFlash, which has long been the standard for embedded systems, is now beginning to be displaced by these new offerings, including Disk on Module, eUSB, SSDDR and the new MiniBlade specification from the Small Form Factor-SIG.
Evolving form factors are synthesizing the hardware requirements for wireless embedded systems into a standardized development platform, thereby enabling innovation, reducing risk and speeding time-to-market. Taking advantage of reduced processor package sizes, form factors continue to decrease in size, enabling increasingly smaller embedded systems for wireless applications.
Computer-on-Modules (COMs) allow a modular systems approach that decouples the processor complex from the remainder of the system, thus alleviating system obsolescence as imposed by Moore’s law. The benefits of a modular approach have led to a proliferation of specifications. The nanoETXexpress specification is a variant of the COM Express standard PICMG, which adds support for PCIe, Gigabit Ethernet (GbE), USB 2.0 and SATA while retaining legacy signal support on a reduced 55 mm x 84 mm form factor utilizing a standard COM Express Type 1 connector.
Another variant of the COM approach is the Qseven specification from the Qseven Consortium, which utilizes standard high-speed MXM connectors to provide high-speed serial signals on a 70 mm x 70 mm form factor. The SFF-SIG, on the other hand, has taken a fresh approach to COM development with the introduction of its Computer on Module Interconnect Technology (COMIT) specification. Rather than focusing on a particular form factor, COMIT is a modular, processor-independent connector system that supports both emerging and legacy signaling common to modern low-power chipsets by way of a rugged, high-density 240-pin connector pair that meets the bandwidth requirements for next-generation PCIe 2.0 and USB 3.0 signaling.
A new generation of mainboard form factors is also emerging that takes advantage of advancements in power efficiency, thermal management, and feature integration to enable ultra-compact, stackable board solutions. The Pico-ITXe specification, originally proposed by VIA, has been adopted by the SFF-SIG specifically for the development of energy-efficient, fanless, x86 systems with a complete range of standard signaling on a 100 mm x 72 mm form factor. Pico-ITXe (and its complementary Pico-I/O specification) utilizes the SUMIT interface while also providing a standardized, modular, SFF expansion specification. The SFF-SIG is also bringing the benefits of SUMIT to the industry-standard 90 mm x 96 mm footprint popularized by PC/104, thereby opening the door to high-speed signaling via PCIe and SATA, with the added versatility of ExpressCard, while retaining legacy signal support. A size comparison of several major form factors is shown in Figure 2.
Relative size comparison of COM (yellow) and mainboard (blue) form factors. [a] nanoETXexpress [b] QSeven [c] Pico-ITXe [d] SUMIT-ISM
The critical role that software plays in the control of power consumption cannot be understated. The Advance Configuration and Power Interface (ACPI) specification is an open industry standard that provides industry-standard interfaces for application control of hardware sleep, performance and throttling states. By proactively controlling the sleep states of hardware via software, system developers are able to reduce power consumption to a fraction of typical system levels. Because entering and exiting deeper power-saving states increases system latency, the ability to invoke the full range of both processor and system sleep states afforded by emerging processors enables power benefits to be adaptively fine-tuned to application performance as needed.
ACPI also enables systems to control device states for powering down auxiliary peripherals when idle, further reducing system power consumption for maximum efficiency and battery life. The open source community, through projects such as Mobile Linux and LessWatts, is contributing best practices and creating standards to realize even greater power savings and accelerate wireless embedded development.
As wireless connectivity proliferates and the processing power available to SFF embedded systems increases, new opportunities are emerging to deliver innovative solutions that harness the true potential of wireless applications. To facilitate these solutions, embedded form factors are evolving to provide open platforms that meet the demanding needs of wireless applications while also providing the flexibility required to adapt to a diverse array of solution possibilities (Table 1). The future of wireless is at hand—all that remains is to realize its full potential for the benefit of humankind.