One of the biggest advantages of Intel® Architecture (IA) processors is the variety of form factors for which the processors are available. Indeed IA popularity means that most new motherboard, bus, and modular standards ship first with IA processors and in most cases embedded design teams have a broad choice of processors for any given form factor. Let's consider the COM Express standard. The COM (computer on module) standard itself was developed so that design teams could choose among various system-on-module products to add to a baseboard that in many cases is specific to an application. And recently, the PICMG group that promulgates the COM Express standard released Rev 2.0 that adds support for features such as digital video and enhanced audio.


At first glance, you might consider COM Express just another one of many small-form-factor motherboard standards designed for compact embedded systems. The standard 95x125-mm size is in the same general size class as the PC/104, Nano-ITX, and ETX standards.


The premise behind COM Express, however, is a bit different from most of the other modular standards. The ITX family of standards for instance, are meant as mother-board standards, around which design teams would build an embedded system. In the case of PC/104, teams customize a system based on a CPU module and additional similarly-sized modules designed for the application. COM Express was meant as a way to offer flexibility in terms of the computer module that's added to a base system or carrier card.


Consider a scenario where a design team develops a medical device or industrial-control system that has a base design in terms of sensors and control electronics. But the team would like to offer a choice of system-level capabilities such as graphics and video support. The team could design the base board as a COM Express carrier and then customize the system with different options in COM Express modules.


Part of the choice in the COM Express scenario can be the processor. But IA platforms often support a range of processors. COM Express allows customization at the system-module level. One option may support HD video while another includes no video support. One might rely on graphics capability integrated in the core logic chipset, while another might integrate a dedicated graphics controller. The point is that the computer system is modular.


The above scenario means that the electrical interface for a COM Express module can be quite different from other small-form-factor standards. The COM Express standard must support a robust set of electrical interfaces that may or may not be used in any given module.


Indeed the need for the robust set of interfaces drove the need for revision 2 of the standard. The original standard didn't support HDMI, but the new one does. Likewise the new version supports DisplayPort. The audio interface was upgraded from AC-97 to HD Audio.


Already there are COM Express modules on the market that take advantage to the new interfaces. For example, Congatec* just announced the Conga-BS57 module that targets maximum computing power and graphics performance.


While COM Express modules are meant to provide the system-configuration options at the module level, companies can still offer a range of processors on a module. Congatec has taken exactly that path with new module offering a range that starts with the Intel® Celeron® U3400 and extending to the Intel® Core™ i7-620.




The module is based on the HM55 Express Chipset with support for up to 8 Gbytes of DDR3 memory. The BS57 supports dual independent video channels over a choice of VGA, LVDS, HDMI, DisplayPort, and SDVO interfaces. Congatec specifically mentions medical imaging and the gaming market as potential targets.


Congatec offers a broad range of other COM Express modules. Choices include products optimized for the Intel® Core 2 Duo and Atom™ processors.


A number of other companies support the COM Express standard as well. RadiSys**, for instance, has a number of such products. Indeed RadiSys recently developed a video on its extended-temperature COM Express Portfolio. Check out the video for more information on the technology and its applicability in rugged applications.


Which modular small-form-factor technologies have you used in embedded designs? Do you have experience with COM Express? What about questions you might have on the topic that your peers may be able to answer? Please share your experience and questions via comments with fellow followers of the Intel® Embedded Community.


Maury Wright

Roving Reporter (Intel Contractor)

Intel® Embedded Alliance


*Congatec is an Associate Member of the Intel® Embedded Alliance

**RadiSys is a Premier Member of the Alliance.