The great dilemma with military I/O technology is accommodating the needs of legacy interface schemes while meeting the performance needs of next-generation computing and electronic subsystems. Legacy I/O schemes such as MIL-STD-1553 and ARINC 429 still are considered good for pure control applications. The problem is they’re not in the same bandwidth ballpark as today’s modern interconnects. Several multipurpose communications protocols provide options to suit emerging needs. The battle continues between legacy military I/O schemes like 1553 and new approaches like using Ethernet as a fabric I/O interconnect. Together 1 Gbit and 10 Gbit Ethernet, Extended 1553 and Fibre Channel are all jockeying to satisfy these needs.

With such a huge installed base, the MIL-STD-1553 bus continues to play a role in a wide variety of systems such as tanks, ships, missiles and satellites. The latest trend to emerge is rugged box-level solutions that include 1553 alongside several other interface technologies. And there’s still a healthy cadre of vendors that continue to support 1553 with board-level products—whether stand-alone 1553 or included with other board or box-level functions. Among those vendors are AIM-USA, Aitech Defense Systems, Alpha Technology, Ballard Technology, Curtiss-Wright, Data Device Corp., Excalibur Systems, Extreme Engineering, GE, Kontron America and Themis Computers.

Board-Level 1553

As old as 1553 is, board-level 1553 products continue to secure design wins. For example last fall, Northrop Grumman awarded GE Intelligent Platforms an order valued at approximately $1 million for quantities of GE’s QPMC-1553 1553 PMCs and CEI-830 ARINC boards that will be used by Northrop Grumman to upgrade its Integrated Avionics System (IAS) that is at the heart of the UH-1Y and AH-1Z (Figure 1) helicopters.

The GE QPMC-1553 PMC and CEI-830 ARINC board are used by the avionics data bus interface, both 1553 and ARINC 429, which is the communications link to the aircraft. The QPM-1553 offers a very high level of performance and flexibility for MIL-STD-1553A/B in the PMC form factor. The CEI-830 ARINC board provides complete, integrated databus functionality for up to 32 channels of ARINC 429, ARINC 575 and selected 2-wire, 32-bit protocols. It supports maximum data throughput on all 32 channels while providing onboard message scheduling, label filtering, multiple buffering options, time-tagging and error detection with support for either 33 MHz or 66 MHz PCI/PMC interfaces.

1553 on Many Form Factors

Long-time specialist in MIL-STD-1553, Data Device Corporation (DDC) earlier this year rolled out a whole new line of rugged 1553/429 embedded and test cards (Figure 2) designed around its next-generation AceXtreme 1553 core, adding Multi-RT capability to DDC’s field-proven and reliable data bus technology. The cards feature a common API that can be used for test cards, embedded cards and components to simplify application code development, shorten software development time and eliminate risk, while the unique I/O mix and high channel count of the hardware reduces space, power, weight and cost. The new line of cards includes PMC, PCI, cPCI and PC/104-Plus versions.

AceXtreme cards are designed to function in extreme environments, and a wide variety of form factors makes them an ideal choice for test/lab environments as well. AceXtreme cards are available in conduction-cooled or air-cooled versions, in the following form factors: PC/104-Plus, PCI-104, PMC, PCI and cPCI. The cards are ideal for systems with limited space yet high I/O requirements, featuring a wide combination and mix of MIL-STD-1553, ARINC 429, Digital Discrete I/O, Avionics Discrete I/O, RS-232/422/485 Serial I/O and IRIG-B input/output on a single rugged, space-saving card. Advanced features include IRIG-106 Chapter 10 onboard formatting, user-selectable BC disable/TX inhibit for safety-critical applications, and an onboard DMA engine for increased data throughput and low host CPU/PCI utilization.

USB as a Test Interface

USB took some time to migrate into the embedded world, and longer still to be embraced as a military I/O interface. One example is Ballard Technology’s portable USB 2.0 interfaces for MIL-STD-1553 and ARINC 429/717 protocols. These easy-to-use USB interfaces enable engineers and technicians to test, simulate and analyze avionics databuses using any available PC. The same device and software can be used in the lab and in the field. Typical applications include product and system development and integration, data loading, flightline maintenance and AOG support, and performance monitoring and analysis. These new USB devices make excellent replacements for plug-in cards, especially hard-to-get PCMCIA cards.

Several models are available with a variety of channel counts and capabilities for the most common aircraft databus protocols—MIL-STD-1553, ARINC 429 and ARINC 717. Units are available with up to 2 dual redundant MIL-STD-1553 channels, up to 16 ARINC 429 channels or up to 4 ARINC 717 channels. A multi-protocol version is also available with 12 ARINC 429 channels and 4 ARINC 717 channels. Weighing less than 5 ounces, these rugged little USB peripherals use the same powerful 5th generation technology as Ballard’s PCI and PCI Express cards.

Ethernet Ties it All Together

One solution system designers have used to get the best of both worlds is to employ network-based solutions such as Ethernet for a sort of dual purpose. Ethernet is used on the one hand as a medium to connect specific high-bandwidth subsystems with each other. At the same time Ethernet is used as a back-end fabric that aggregates new, faster I/O technologies alongside slower legacy buses like 1553. This type of solution lends itself to more complete system- or box-level I/O solutions, some of which even embed processing.

For a variety of military programs, Ethernet switch boards have won a place as a critical building block. Looking for a faster solution than 1553, aircraft system integrators are looking for an easy way to implement Gbit Ethernet to handle high-bandwidth elements such as multifunction displays, moving maps and multiple full rate video feeds. Where once Ethernet was used only as a pure networking solution for command and control systems in the military, Ethernet is now gaining traction in numerous other military applications as an interconnect fabric in compute-intensive applications.

Ethernet on OpenVPX and More

Rugged Ethernet Switch products are available in many form factors, including VME, VXS and VPX. Switched Ethernet technology is finding its way into numerous programs. OpenVPX with its many defined profiles has Ethernet as one of its prominent options. For loosely coupled systems, Ethernet or PCI Express are expected to be the dominant OpenVPX fabric choice. This will appeal to military systems that are very communications- or networking-based—for example ad hoc networks with RF. Ethernet fits in well with the military’s push toward an Everything-Over-Internet Protocol (EOIP) strategy leveraging the ubiquitous ecosystem of TCP/IP and Ethernet technologies.

Offering a VPX-based rugged box system, Extreme Engineering Solutions (X-ES) offers its XPand3200 system (Figure 3) that supports both 3U VPX and cPCI backplanes. Measuring 4.88 x 5.62 in x 8.75 inches, the unit is a sub-½ ATR-sized conduction-cooled, fully ruggedized system designed to meet the rigorous standards of MIL-STD-810F. The system is aimed at avionics, UAVs, AUVs and vetronics requirements.

Depending on processing requirements, the XPand3200 can be populated with 3U modules from X-ES based on the Intel Core2 Duo processor, the Freescale dual-core MPC8572E PowerQUICC III processor, or the Freescale dual-core MPC8640D processor. The XPand3200 can then be configured to meet I/O requirements. The XPand3200 supports Gigabit Ethernet, graphics, RS-232/RS-422/RS-485, MIL-STD-1553, MIL-STD-188-114A, ARINC 429, discrete I/O, as well as custom conduction-cooled PMC/XMC I/O through the back panel D38999 circular connectors. An optional 32 Gbyte SATA SSD memory module provides the convenience of removable storage and the ruggedness of solid-state memory. An optional USB port provides system monitoring and maintenance capabilities.

I/O in Box-Level Systems

The emerging trend toward complete box-level systems has broadened to include some offerings that incorporate a variety of military-specific I/O. An example along those lines is Aitech Defense Systems’ NightHawk RCU, an extreme rugged, compact Intel Atom-based, self-contained control unit that weighs only 4.5 pounds. This unit offers a slim profile and natural convection/radiation cooling that dissipates up to 22W at +55°C in stagnant (non-flowing) air, or at up to 71°C with an optional low pressure fan or baseplate.

Based on the low-power Intel Atom processor operating at 1.6 GHz, the new NightHawk provides up to 2 Gbytes of DDR2 SDRAM as well as between 4 and 8 Gbytes of SSD memory with an optional expansion up to 250 Gbytes for extended and remote data collection and storage applications. With a complete set of standard PC I/O interfaces, the NightHawk also provides two Gbit Ethernet ports, six USB 2.0 ports and four multi-function RS-232 serial ports, dual graphics/video ports, keyboard/mouse and stereo audio in/output ports as well as an I/O set specifically tailored for embedded military applications. Optional I/O includes MIL-STD-1553B, ARINC-429 and ARINC-708, CAN Bus, Wi-Fi and WAN ports as well as video capture and processing, discrete and analog I/O and an eight-port Gigabit Ethernet switch.

Multifunction Board Trend

Another important trend affecting military I/O is the emergence of multifunction board products. Semiconductor integration has enabled board-level products to cram multiple functions on a single card. Along just such lines, North Atlantic Industries (NAI) has made available ARINC429/575 support for its wide range of VPX, VME, cPCI and PCI Multifunction boards (Figure 4). Known as the A4, it joins an extensive list of functions that are currently available from NAI. The ARINC 429/575 A4 provides up to six programmable ARINC-429/575 channels. Each channel is software selectable for Transmit and/or Receive, High or Low Speed, and Odd or No Parity, supporting multiple ARINC429 and 575 channels simultaneously.

One major advantage of this multifunction approach is higher functional density, which reduces overall board count, thereby saving space and cost, reducing heat dissipation and increasing overall system reliability. Other available functions include A/D, D/A, Synchro/Resolver/ LVDT/RVDT Simulation and Measurement, CANBus, MIL-STD-1553, Synch/Asynch RS232/422/485, Discrete, TTL/CMOS, Reference Generator, Differential Transceiver and Resistance Temperature Detectors (RTD). The ARINC429/575 function is supported on VPX, VME, cPCI and PCI Multifunction Boards with operating temperature ranges of -40° to +85°C and 0° to +70°C.  

Aeronix
Melbourne, FL.
(321) 984-1671.
[www.aeronix.com].

AIM-USA
Elkhorn, NE.
(866) AIM-1553.
[www.aim-online.com].

Aitech Defense Systems
Chatsworth, CA.
(888) 248-3248.
[www.rugged.com].

Alphi Technology
Tempe, AZ.
(480) 838-2428.
[www.alphitech.com].

Ballard Technology
Everett, WA.
(425) 339-0281.
[www.ballardtech.com].

Curtiss-Wright Controls Embedded Computing
Leesburg, VA.
(703) 779-7800.
[www.cwcembedded.com].

Data Device Corp.
Bohemia, NY.
(631) 567-5600.
[www.ddc-web.com].

Excalibur Systems
Elmont, NY.
(800) MIL-1553.
[www.mil-1553.com].

Extreme Engineering Solutions
Middleton, WI.
(608) 833-1155.
[www.xes-inc.com].

GE Intelligent Platforms 
Charlottesville, VA.
(800) 368-2738.
[www.ge-ip.com].

North Atlantic Industries.
Bohemia, NY.
(631) 567-1100.
[www.naii.com].

Kontron America
Poway, CA.
(858) 677-0877.
[www.kontron.com].

Themis Computer
Fremont, CA.
(510) 252-0870.
[www.themis.com].