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.