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Small embedded computers—in both standard and non-standard form factors—are in high demand for military applications that are extremely space- or weight-constrained or where traditionally only a fully custom solution would do the job. When it comes to standard form factors, this industry segment was—until just these past couple of years—holding its breath. But today, even though there are significant differences in strategy among the various small embedded computing standards groups, the overall results are positive.
In some cases disagreements about technology standards can sometimes slow down progress. But in this case it seems to be sparking a lot of innovation. Such computing technology—although always of interest to the military market—is becoming ever more critical for defense applications. These include small UAVs, robotics, mission-specific handheld systems, intelligent munitions and many others. The Scan Eagle UAV, for example, has a PC/104 SBC as part of its network control subsystems. Scan Eagle is a small GPS-guided UAV that can fly up to 15 hours and transmit real-time imagery directly to its home link.
Different Standards Approaches
In this area of the embedded computer market, there are three groups that take different—although often overlapping—views on how to move forward with standards-based small form factor technology. The PC/104 Consortium seems to favor marrying PCI Express with the tried and true PC/104 form factor. The Small Form Factor Special Interest Group (SFF-SIG) meanwhile is focused on trying a variety of different approaches to suit the miniaturization of board-level electronics. Unlike the others, the SFF-SIG is pushing the idea that the connector interface scheme can and should be independent from mechanical board form factors. And not to be left out, the StackableUSB camp remains focused on using USB (and I2C and SPI) to replace ISA as the board-to-board interconnect in rugged stacked systems.
Although it was only formed about two years ago, the SFF-SIG has been quite productive in its accomplishments so far. At ESC San Jose earlier this year, the SFF-SIG followed up on its earlier work by ratifying Revision 1.0 of the MiniBlade spec and also introducing a new revision to its SUMIT specification. SUMIT Interface Standard Revision 1.3 supports four additional PCIe x1 lanes for a total of six, one additional USB 2.0 interface for a total of four, and DMA support on the LPC bus to enable higher-speed data transfers. The update is fully upward compatible with the earlier SUMIT version.
Perhaps the most interesting SFF-SIG development this year is its rollout of a new form-factor-independent, Computer-on-Module interface standard. Called COMIT (Computer On Module Interconnect Technology), this electromechanical interface specification is designed to be processor-independent and focuses on bus interconnect and module manufacturing technology rather than any single processor, DSP, or microcontroller architecture. The idea is to use COMIT to support different processors with a single baseboard, allowing easy migration to future processors. Both concepts are well suited to the performance/feature tech upgrade and obsolescence mitigation needs that are so key for the military.
Putting that concept into action, WinSystems at last month’s Boston ESC show, announced their EBC-Z8510-G SBC that supports both the SUMIT-ISM I/O expansion standard plus COMIT (Figure 2). The board is powered by an Intel 1.1 GHz Atom processor and measures 203 mm x 147 mm (8.5 x 5.75 inches). With a blend of high-bandwidth PCI Express (PCIe) lanes, USB ports and lower-speed multiplexed and serial buses, SUMIT and COMIT can be added to a variety of board form factors, and is flexible and compact enough to meet a very broad range of application requirements.
In recent standards activity, the SFF-SIG at ESC Boston announced the availability of revision 1.0 of both the Pico-ITXe and Pico-I/O Specifications for small, rugged, stackable embedded systems. The Pico-ITXe Specification builds on the momentum of the unexpandable Pico-ITX standard to enable stackable I/O expansion using SFF-SIG’s flexible SUMIT (Stackable Unified Module Interface Technology) interface. Pico-ITXe boards are the same size (72 x 100 mm) and have the same mounting hole placement as Pico-ITX boards allowing easy migration to support SUMIT-based, stackable I/O modules.
Expansion for Pico-ITX Form Factor
The Pico-I/O Specification defines small 60 x 72 mm stackable I/O expansion modules for use with Pico-ITXe or, in fact, any other SBC form factor that incorporates SUMIT expansion with Pico-I/O mounting holes. Stackable I/O expansion is implemented using the SUMIT standard. Through the inclusion of one or two 52-pin SUMIT connectors, a PicoITXe SBC can provide PCI Express (up to five x1 lanes or two x1 and 1 x4 lanes), four USB 2.0, LPC, I2C and/or SPI interfaces to the Pico-I/O modules. In anticipation of the release of these Specifications, VIA Technologies has rolled out a Pico-ITXe SBC, and Pico-I/O modules are available from member companies ACCES-I/O and WinSystems as well as VIA.
For its part, the StackableUSB camp at ESC introduced the concept of using other standard format embedded boards as carrier boards for Stackable USB modules. The idea is for StackableUSB Clients to be used in conjunction with any Nano-ITX, Pico-ITX or full-size PC/104 Form Factor single board computers. This is made possible by the use of carrier boards that conform to each of these popular SBC form factors. These carrier boards attach to the SBC and provide up to four USB mounting bays for StackableUSB Clients. For SBCs that don’t have a StackableUSB connector, a USB cable can be used to attach the carrier board to the SBC.
In keeping with a strategy of preserving ties to legacy PC/104, the PC/104 Embedded Consortium’s major ESC announcement was the addition of USB connections to the stackable PCI/104-Express and PCIe/104 specifications. Since the adoption of those two specs a year ago, a number of vendors have rolled out products based on the PCI/104-Express and PCIe/104 specs. The addition of the industry-standard USB will help provide quick connectivity for add-on modules that have USB-driven devices. Interestingly, the result of marrying USB and PCI Express to the PC/104 world may eventually be the elimination of PCI bus for the PC/104 realm, even though the venerable ISA bus will still have a place. Any application—whether it’s in the embedded or desktop/server space—that needs performance will want to migrate to PCI Express or USB anyway. In contrast, ISA still has a role as a low-speed, easy-to-implement interface to sensors, analog/digital I/O and so on.
Atom CPU Makes an Impact
Aside from form factor standards, the most significant trend impacting small form factor boards in the past year has been the proliferation of boards based on Intel’s Atom processor. The Intel Atom processor has been among the top architectures on new SBC products over the past year. The emergence of the Atom means there’s no longer a reason to suffer with high power dissipation as a trade-off for using an Intel Architecture platform. The Intel Atom processor Z5xx series provides a variety of design options with 2.0 or 2.2W power levels, two package sizes and industrial as well as commercial temperature ranges. The Atom’s low power makes it suited for the kind of Size, Weight and Power (SWaP)-constrained applications–small UAVs, UGVs, portable comms gear and so one—that are so critical these days. For the military, a key point is that the Atom has embedded lifecycle support. Military system designers were reluctant to consider the Atom until the assurance of 15-year part availability was offered.
COM Express, meanwhile, has taken its place as the new standard for bus-less embedded computing. COM Express safeguards development investments and lowers total cost of ownership by enabling designers to partition commodity host-processor COM Express modules from proprietary, value-added platform building blocks, including FPGAs and specialty I/Os on custom baseboards.
Marrying both the COM Express and Atom trend is ADLINK Technology’s Express-ATC (Figure 3), the newest member of its Computer-on-Module (COM) family. The Express-ATC is a “Compact” COM Express module measuring only 95 x 95 millimeters, and is fully compatible with the Type 2 pin-out of the PICMG COM Express specification. Based on the ultra-low-power Intel Atom N270 processor and Mobile Intel 945GSE Express chipset, the Express-ATC comes with integrated support for high-resolution CRT, single/dual channel LVDS and TV out (SDTV and HDTV). The Express-ATC supports up to 2 Gbytes of DDR2 533 MHz memory on a single SODIMM socket. The module supports three PCI Express x1 lanes via the Intel I/O Controller Hub 7-M (ICH7-M) Southbridge, one Gbit Ethernet connection and two SATA channels. Legacy support is provided for a single Parallel ATA channel, 32-bit PCI and Low Pin Count bus (LPC). The Express-ATC supports onboard IDE-based Solid-State Drive (SSD) up to 8 Gbytes, and comes standard with an integrated Trusted Platform Module (TPM 1.2).
The latest COM Express offering from American Portwell is a Type II COM Express Basic (small footprint) that has a footprint of 125 mm x 95 mm (4.92 x 3.74 inches). The compact PCOM-B213VG includes the GM45 and ICH9M-E chipset and integrated GMA 4500HMD graphic engine that supplies extreme 3D performance for media applications such as high-definition 1080p imaging. Active Management Technology (AMT) 4.0 and Trusted Platform Module (TPM) support effective remote management and enhanced security. Two SO-DIMM sockets support DDR3 SDRAM up to 8 Gbytes and the board has both EIDE and SATA as well as one Gigabit Ethernet. I/O expansion (via the Com Express carrier board) includes one PCI-E x16 multiplexed with SDVO interface, five PCI-E x1, four PCI, LPC interface and high-definition audio interface, and a PCOM-C210 Developer COM Express Type II carrier board.
Compact COM Express Version
Kontron’s latest COM Express offering is a microETXexpress evaluation kit aimed at providing system developers a fast introduction into the compact class of COM Express-compatible Computer-on-Modules. At the heart of the kit are the Kontron microETXexpress-SP or -DC Computer-on-Modules (95 x 95 mm) based on the Intel Atom series processors and the Kontron ETXexpress miniBaseboard. Starterkits are also available for evaluation with other microETXexpress modules. Thanks to its low profile height of approximately 44 mm—including the Computer-on-Module and the optional heat spreader—it can easily be integrated into space-constrained military embedded applications.
Military I/O specific boards have also embraced the small form factor trend. And in this era of the multifunction board, the PC/104 space is riding that trend too. PC/104 is well accepted in the military realm. Serving those needs, Data Device Corp. teamed with Advanced Digital Logic (ADL) to supply PC/104-Plus and PCI-104 cards for use in applications that require MIL-STD-1553 or ARINC 429 interfaces. DDC and ADL have proven interoperability of DDC's BU-65578C MIL-STD-1553 card and BU-65590C (Figure 4) Multi I/O (1553 and 429) card with the ADL systems.
DDC’s cards provide a mix of MIL-STD-1553 and ARINC 429 Receive/Transmit Channels along with user-programmable digital discrete or Avionics Discrete I/O, selectable external or internal time-tag clock, and an IRIG-B time synchronization input and output. The cards have an intelligent hardware offload engine that dramatically reduces PCI bus and host CPU utilization, while storing 1553 Monitor data in a convenient and portable IRIG-106 Chapter 10 file format.
Dime-Sized SOM Solution
Representing the ultra-small portion of the small form factor computer trend, Logic recently rolled out its dime-sized Torpedo System on Module (SOM) and Development Kit, based on Texas Instruments' OMAP 3 processor family. The Torpedo SOM (Figure 5) is an ultra-compact form factor for applications that require low power and high performance within tight space constraints. By using the 0.4 mm BGA pitch OMAP processor that leverages Package-on-Package (PoP) technology, the dime-sized Torpedo SOM requires 45 percent less surface area and 12 percent less volume when compared to the equivalent OMAP 0.65 mm BGA package and external memory solution. A discrete design using the 0.4 mm BGA package usually requires advanced PCB technologies that result in higher board costs in addition to PoP technology, which requires specialized manufacturing assembly processes. The Torpedo SOM solves these development complexities; as a result, customers can design lower cost baseboards and use common manufacturing procedures while still benefiting from the small package OMAP35x processor and PoP technology.
San Jose, CA.
Data Device Corp