It looks like the PCI-X, the new PCI
extension, will become a real standard for embedded systems as well
as one for PC servers. And PCI-X is needed; it cleans up PCI and
opens up PCI's bandwidth potential, especially for burst
transactions. Additionally, PCI-X solves the limiting "PCI Read
Problem," enabling PCI Reads to achieve PCVI Write
PCI-X infrastructure is slowly being winched into place,
building a design base for PCI-X systems. Coming online are:
- PCI-X bus controller cores for ASIC implementations
- PCI-X bus controller cores for FPGA implementations
- PCI-X testers for cards
- PCI-X compatibility for common peripheral control chips that
now interface to PCI.
PCI-X had a difficult birth, starting out with two strikes
against it. These include that:
- It was developed by Compaq, HP, and IBM, not Intel and
- PCI-X was caught up in the Intel NGIO vs. Big Three Future I/O
But PCI-X has managed to survive and is now on its way. PCI-X
products are expected to start to emerge in the latter part of this
year. First out of the box will be PCI-X implementations in PC
servers, probably from the Big Three—Compaq, HP, and
IBM—and their PCI-X allies. Both Compaq and IBM are on record
as supporting PCI-X in their PC servers by the end of the year.
Additionally, bridge chips and cores are also on the way.
An FPGA Core
FPGAs are the utility fielders of board level design. Much of
the glue logic, specialty functions and bus controllers on a board
find their way to one or more FPGAs in many designs. And today, PCI
cores are now offered as IP by the leading FPGA vendors. And now
PCI-X has a core controller for FPGAs on the way. Altera is
implementing Compaq's PCI-X bus controller, as a core for its
FPGAs. This Altera PCI-X MegaCore function was originally
implemented by Compaq in multiple ASICs. It implements a 64-bit
master/target PCI-X interface, but supports both 32-bit and 64-bit
operation. It is available in Verilog HDL
This PCI-X core is being implemented now and is currently being
characterized for drive and operation. Designers expect that the
combined core and FPGA I/O will be able to work at both the PC
system I/O bus level and at the system bus level. Drive capability
is expected to reach five to seven boards.
Insilicon has announced a PCI-X design package, TymeWare. This
package integrates a PCI-X bus controller with a bus test
environment. The core is made up of synthesizable RTL blocks that
can be used for ASIC or FPGA development of a PCI-X bus controller.
The core and test environment are available in Verilog HDL source.
The PCI-X development environment includes both PCI 2.2 and PCI-X
behavioral models (master, target, and arbiters) and a
protocol/timing monitor. The test environment also comes with a
full set of compliance tests for both PCI-X and PCI 2.2 (www.in-silicon.com
DCM Technologies also supplies a PCI-X bus controller core, the
Corex-V10 PCI-X. This core comes in a netlist version that supports
133-MHz, 64-bit PCI-X operation. In fact, DCM is pushing the core
controller's 133-MHz operation as an enabler for high-bandwidth
Gigabit Ethernet. DCM also sells a conversion board that plugs
PCI-X into a standard PCI slot for test and evaluation (www.dcmtech.com).
Testers to the Fore
One very encouraging sign is that major board tester vendors are
bringing out testers for the PCI-X bus. Agilent, Catalyst, and
VMEtro are all fielding PCI-X testers and exercisers. And these
testers, like many bus testers today, have the advantage being
plug-in units. They plug into the very buses they test. All you
need is an extra slot to accommodate the tester card.
These testers are designed to test the PCI-X bus and to exercise
it as well. You can just drop them in. And then text and exercise
your PCI-X implementation. These testers all come with a host-based
GUI environment that enables designer to look at test results as
well as interactively exercise and debug the bus.
Agilent—Its E2929A PCI-X Exerciser and Analyzer
supports 32-/64-bit with bus rates to 133.4-MHz operation. It
consists of a PCI-X Protocol Checker, a PCI-X Analyzer, a PCI-X
Exerciser and a C-API Interface, and PPR (software). Its PCI-X
protocol checker verifies 53 PCI-X protocol implementation rules.
The tester also provides the option to link a logic analyzer to the
PCI-X signals for deeper signal analysis. It comes with a
ready-to-use library of stress tests. The E2929 is a short PCI
Catalyst—Its TA700 PCI/PCI-X Analyzer and Exerciser
supports 32-/64-bit, 66-MHz bus operation. It has a 750-MHz timing
analyzer and a 10-GHz (100-ps) set-up and hold timing violations
detector. It has automated PCI Device Compliance test and
verification. This unit can be controlled from the PCI-X bus itself
by the system host. Additionally, the PCI-X tester card has an
auxiliary PCI expansion connector on top for accepting a PCI
VMEtro—Its PBT-615 PCI-X Bus Analyzer and Exerciser
supports 32-/64-bit operations with speeds up to 100-MHz (sampling
rate). It has a 500-MHz Timing Analyzer with a 16 Msample trace
buffer. It also supports PCI at rates up to 66-MHz operation. It is
a short PCI formfactor card. It connects to a host PC via a front
panel connector with USB or RS-232 serial connections.
See PCI-X Exposed for the PCI-X