October 2014
23
B
OARDS
& M
ODULES
size. Though they are compact (ETX/XTX at
114x95mm and COM Express at 125x95mm
to 84x55mm) and highly integrated, COMs
can accommodate complex CPUs.
With the COM approach, all generic PC func-
tions are readily available in an off-the-shelf
foundation module, allowing system devel-
opers to focus on their core competencies
and the unique functions of their systems. A
custom-designed carrier board complements
the COM with additional functionality that
is required for specific applications. The car-
rier board provides all the interface connec-
tors for peripherals, such as storage, Ethernet,
keyboard/mouse and display. This modularity
allows the designer to upgrade the COM on
the carrier board without changing any other
board design features, and also allows more
customization of peripherals as dictated by a
specific application. The COM Express form
factor offers flexibility in the development
and advancement of ultra-rugged embedded
applications for a wide range of industries.
By using the modular processing block, the
designer creates a price and value advantage;
he or she isn’t locked into a single vendor
for board creation and can customize based
on pricing and performance requirements.
Because it is easily swapped from a carrier
board and comes in one of the smallest form
factors, COM Express is ideal for long-life
embedded applications with a critical devel-
opment cycle, as well as more progressive
applications that require frequent processor
upgrades without affecting other application
design elements.
Rugged solutions are most often housed out-
doors or in moving vehicles, where exposure
to a variety of climates dictates the need to
operate in extended temperatures and to
power up in any extreme. The easiest initial
step is to select a rugged board or system that
is designed for harsh environments from the
ground up. To support the extremes of shock,
vibration, humidity, and temperature, care is
given to component selection, circuit design,
printed circuit board (PCB) layout and mate-
rials, thermal solutions, enclosure design, and
manufacturing process. Robust test meth-
ods, including highly accelerated life test-
ing (HALT), ensure optimal product design
phases in order to meet the stringent require-
ments of a product, such as -40 °C to +85 °C
Figure 1. The PC/104 embedded computing format has no backplane, instead allowing modules
to stack together like building blocks. Many applications in defense and transportation still
incorporate legacy devices that require an ISA-BUS interface.
