TECHNOLOGY FOCUS COM and COM Express Boards
COM Express Rides Wave of Integrated Electronic Systems As increasing levels of semiconductor integration enable ever more powerful computing in smaller spaces, the COM Express form factor is uniquely positioned to gain military mindshare. Jeff Child Editor-in-Chief
he Computer-on-Module (COM) concept has found a solid and growing foothold in military embedded systems. COM Express adds high-speed fabric interconnects to the mix. COM boards provide a complete computing core that can be upgraded when needed, leaving the applicationspecific I/O on the baseboard. In many ways, COM boards have a guaranteed inside track for future success. That’s because the continual progression of semiconductor integration means that a single computing module will only get more powerful. And at the same time, the argument for a two-board solution— COM module and baseboard—only gets stronger as complete system electronics are possible on a single baseboard. That doesn’t mean other, larger solutions— like slot-card boards or stackable solutions like PC/104—are going away any time soon. But the mindshare COM Express can gain for military applications will keep increasing. COM Express’ comparison to PC/104—including PC/104 family specifications like PCI-104-Express and so on—is particularly relevant because both are suited for space- and weightconstrained applications. If a large stack 40
COTS Journal | August 2013
isn’t required for any reasons, the doublesided connectors of PC/104 are hard to justify because they are more costly than single-sided connectors used by COM Express. Beyond cost, double-sided connectors also use up more board space because single-sided connectors can have components placed on both sides of the board. A COM Express implementation has just two layers comprising a computer module and a carrier board. The carrier board incorporates all the custom I/O that would be in a PC/104 stack. Because space is a premium and more functionality is always in demand, Unmanned Ground Vehicles are an example of the kind of military application well suited to a COM Express solution (Figure 1). There are three COM Express module sizes to choose from to suit their individual application requirements. All signals are maintained on the carrier card, where additional connectors can be added as required per specific applications. As a macro-component, COM Express enables technology insertions without a large time or monetary investment, and supports easy upgrades through multiple product lifetimes. When COM Express was created, the spec planned for the expansion of video and display capabilities, and it provides standard connector access for a variety of high-speed interfaces. The COM Express connector supports multiple video interfaces including DisplayPort, VGA, SDVO, HDMI and DVI. This allows designers to take advantage of the latest graphics capabilities without having to worry about affecting performance. Another advantage of COM Express is that it lets users handle transitions from legacy connectors and offers native interface support for modern-day I/O interfaces. On top of offering more PCI Ex-
Built by iRobot, the PackBot is a series of Unmanned Ground Vehicles designed to inspect and clear suspicious objects during improvised explosive device (IED) sweeps. These systems generally include a remote controlled articulated arm with a gripper and a pan/tilt color surveillance camera. press and USB ports than PC/104-Express modules, additional connecters can be added for LAN, SATA, video, audio, USB and PCI Express, delivering maximum I/O flexibility to meet specific application requirements. Because signals don’t have to pass through multiple connectors, the signal integrity remains intact. Last summer PICMG announced that they adopted the 2.1 revision of the COM Express specification. That revision added new features and module sizes, and helped ensure that COM Express modules are prepared for future processors and high-speed I/O evolution while accommodating backward compatibility with older modules. Significant enhancements of the COM Express Revision 2.1 specification include standardization of new and smaller module sizes, extended power supply range and support of the latest graphics interfaces. USB 3.0 and CAN Bus support are also included.