Established standards like PCI Express, Serial Rapid-
IO, Ethernet, and InfiniBand are making way for
a host of new products based on them. This is true
for device interfaces including USB, Serial ATA
(SATA), and Serial Attached SCSI (SAS). Still, a significant
chunk of shipments will continue to use legacy interfaces
like IDE, PCI, and ISA.
Processor Interconnects
Processor interconnects
will see changes this year, at least when it comes to Intel’s
offerings. The forthcoming “Nehalem” architecture will
employ a new interconnect system named QuickPath, which
is a point-to-point, distributed shared memory architecture.
QuickPath brings the memory controller into the processor
chip. It links multiple chips together with high-speed
links in a non-uniform memory access (NUMA) approach,
which is very similar to AMD’s HyperTransport interconnect
for the Opteron.
ASUSTeK’s KFN5-Q is one example of a four-way Opteron
motherboard (Fig. 1). The “Nehalem” architecture will
also
include features like simultaneous
multithreading (SMT), which will support
two
to 16 threads per chip depending
upon
the number of cores.
Of course, HyperTransport is now in
its third incarnation. It has an aggregate
bandwidth of 41.6 Gbytes/s and an
optional ac operating mode designed for
cabling and backplanes. It even supports
hot-plugging.
The HTX board connection is defined,
but only a few boards are available for
these sockets. It will be interesting to see
the final specs for QuickPath, as Hyper-
Transport already has about a third of the latency of PCI
Express.
PCI Express IO Virtualization
PCI Express
is pushing its way into everything, from PC
motherboards to PXI Express boards to COM Express
modules. It is slowly knocking PCI out of the
equation and is looking to make further changes in
the server market with the forthcoming PCI Express IO
Virtualization support.
The missing components, the processor chip sets, will be
available this year. The matching support in the processors
is in the latest incarnations. Creating these chip sets isn’t
easy, but the payoff is significant. They will work with switch
chips like PLX Technology’s PEX 8648 (Fig. 2) and boards
such as Intel’s 82598 Ethernet adapter (Fig. 3).
The 82598
adapter provides
16 virtual-machine
device queues
(VMDq). It will
allow device drivers
on virtual machines
running on the host
processors to access
the virtual hardware
directly instead of
going through proxy
device drivers, removing
the last roadblock
in end-to-end virtualization.
Machine virtualization is just being adopted for embedded
applications. Still, I/O virtualization will eventually play
a significant role in embedded environments because of its
security and efficiency implications.
Speedy Serial Backplanes
PCI Express continues
to have an impact on high-speed serial backplanes and
mezzanine cards with alternatives like 10-Gbit Ethernet,
Serial RapidIO, and InfiniBand fitting into their own niche
application areas. Products based on standards like CPCI/
Express, VPX, and AdvancedTCA will be available.
Look for larger and more robust Serial RapidIO and
InfiniBand switch chips. The rising number of endpoints
within systems will require these faster and more highly
integrated chips. Switch and endpoint chips will incorporate
more intelligence, like Integrated Device Technology’s
70K2000BR Serial RapidIO preprocessing switch chip (see
“One Smart Serial RapidIO Switch”).
Look for high-performance
products in the
3U form factor like the
CPCI/Express singleboard
computer (SBC)
from Men Micro. The
MEN-A-5560 F18 comes
with an Intel Core 2 Duo
processor (Fig. 4). This
form factor is also home
for platforms like VPX.
AdvancedTCA will continue its march through serial
backplane country. However, this will be the year of MicroTCA,
AdvancedTCA’s smaller sibling. By finally clearing
the standards hurdle, MicroTCA will come into its own.
MicroTCA systems like
Emerson’s EMC6000 will be
shipping (Fig. 5). MicroTCA
uses the same Advanced
Mezzanine Card (AMC)
as AdvancedTCA, so a
variety is already available.
Interest for MicroTCA is primarily in
the communications market, but there
is a push to simplify the standard and
move it into other embedded application
areas.
Embedded USB
The Universal Serial
Bus (USB) may get a speed boost in
the near future, but it is more than
adequate for most embedded applications
today. USB has been used for
data acquisition and control outside
the box with products like Acces IO
Products’ USBDA12- 8E eight-channel
analog output module (Fig. 6). However,
it is moving inside the box more
and more.
Flash memory cards are populating
USB headers on motherboards. Microcontrollers
that have access to hard
drives and optical disk drives but lack
SATA and IDE interfaces are providing
access to hard drives and optical
disk drives. Wireless adapters also are
easily incorporated via USB.
Some wireless technologies like
802.15.4/ZigBee work with interfaces
like I2C and SPI, but USB is still the
one interface that is available across
the board. USB is also the control
interface of choice for video. USB
cameras for laptops and desktop PCs
have enabled this area, making it
relatively simple to incorporate video
input into an application.
Video Interconnects
Video output
is going to be a
challenge, though,
with over a dozen
standards and
growing interest
in higher-performance links.
Composite video and VGA interfaces
still abound but definitely do not represent
the cutting edge.
DVI is the high-performance standard
for most PC and mezzanine video
cards this year, with DisplayPort in the
wings and HDMI of growing interest.
HDMI tends to be the consumer
standard, driven by high-def devices
like HD DVD and Blu-ray disk players.
Of course, embedded designers may
take advantage of the plethora of large
displays available with HDMI interfaces
for applications such as digital signage.
Don’t overlook one of the key
benefits of HDMI: bi-directional communication.
It’s having a significant
impact in the consumer space, allowing
multivendor component solutions
to work together.
Storage Interconnects
Serial
ATA has taken the consumer market
by storm. So has Serial Attached SCSI
(SAS) in the enterprise arena. Life at
3.0 Gbits/s is good and will remain so
for a few years.
The performance
and
availability of
eSATA is
moving
high-performance
external
storage away
from USB and
IEEE 1394.