CompactPCI and AdvancedTCA Systems - OpenSystems Media

P R O D U C T G U I D E
P A C K A G I N G
legacy PXI boards, where the P2 connector
is replaced with the eHM connector,
can be used in the hybrid slot.
Switch slot
This slot provides fan-out to drive all of
the slot types. It contains a power connector
and a large number of ADF connectors
to accommodate all of the signals coming
in from each slot. The 3U sized switch
slot contains three ADF connectors and
can connect up to seven slots with x4
ports. The 6U switch slot contains eight
ADF connectors and can connect up to
19 slots with x4 ports. Dual switch slots
can be included in a backplane to provide
redundant ports to each slot.
Hybrid systems:
Compatibility with existing boards
Over the next several years, CompactPCIe
systems will likely include a mixture of
legacy slots, hybrid slots, and new PCIe
slots. This will enable designers to mix
and match older boards with newer highperformance
boards. Over time, more and
more of the slots are expected to migrate
to the PCIe standard.
CPU modules will likely be the first modules
to migrate to PCIe, given the rapid
CPU board design turnover rates and
because newer chipsets have PCIe ports.
Generic I/O boards such as Ethernet,
video, and disk controller boards will
migrate to PCIe next. Again, the underlying
components will drive this transition.
The latest components for these functions
are now coming out, and they have PCIe
ports coming directly out of the chip.
Thus, new designs using the latest components
will utilize PCIe.
The last boards likely to migrate over to
PCIe will likely be custom or low-volume
specialty I/O boards. Some designers may
choose the “easy” way out and add a PCIto-PCIe
bridge onto these boards. This
minimizes the engineering effort involved
in getting a legacy board to work in a pure
PCIe environment. Although easier, this
approach does not achieve the performance
advantages of PCIe, since the transfers
end up going though legacy PCI and
are throttled by its lower performance.
Future performance increases:
Gen 2 timing
The PCI-SIG has announced the next
generation PCIe bus timing. In PCIe 2.0,
the data transfer rate will double from
2.5 gigabits per second to 5.0 gigabits per
second. Components with the new Gen 2
timing are expected to become available
in early 2007, with systems appearing
shortly thereafter.
The technical subcommittee that defined
CompactPCIe took the future Gen 2 timing
into consideration when defining the
specification. All simulations for the proposed
backplane and connectors occured
at frequencies beyond Gen 2, providing
confidence that the upgrade path will be
straightforward.
The specification is defined such that
Gen 2 boards will be compatible with the
current backplanes and boards. In a mixand-match
system, each bus interface
will auto-negotiate with its associated
interface. They both will begin communications
at the slower 2.5 gibabits per second
speed and then let each other know
if they have the capability to move to
5.0 gigabits per second. Due to the pointto-point
nature of PCIe, the presence of
Gen 1 boards will not slow down highspeed
Gen 2 boards in the same system.
This technique will allow systems to take
advantage of even higher bus performance,
while maintaining total hardware
and software compatibility.
Steve Cooper is president and CEO of
One Stop Systems, and has more than
18 years of sales, marketing, and general
management experience in the standard
bus and board marketplace. He began
his career with Intel, where he became a
technical spokesman for the concept of
board-level open bus standards and the
Multibus and Multibus II architectures.
Steve then joined RadiSys, a company
specializing in embedded PC-compatible
computers. He also served as vice president
of sales and marketing, and later
president and chief operating officer, at
I-Bus. Most recently, Steve was president
and chief operating officer for
SBS Technologies. He holds a BSEE
degree from the University of California,
Santa Barbara.
To learn more, contact Steve at:
One Stop Systems
735 South Vinewood St.
Escondido, CA 92029
Tel: 760-745-9883
Fax: 760-745-9824
E-mail: scooper@onestopsystems.com
Website: www.onestopsystems.com
38 / CompactPCI and AdvancedTCA Systems / September 2005