Teledyne LeCroy
PCI Express Mid-Bus Probe for Summit Analyzers
Version 1.1
4
1 Introduction
Teledyne LeCroy offers a wide variety of ways to connect PCI Express protocol analyzers to products under test. There
are four common methods: Interposers, Specialty Probes, Mid-Bus Probes and Multi-lead Probes.
If the product uses a standard PCI Express card connector, an interposer is used which is inserted between the PCIe
Card and the card slot. The interposer taps off the data traffic to allow the analyzer to monitor and record traffic with
minimal perturbation of the electrical interface.
Specialty probes are used with specific card configurations, and are used in the same manner as an interposer card (in
fact a specialty probe is an interposer card designed for a specific interface). LeCroy supports a range of specialty probes
including ExpressCard, AMC, XMC, ExpressModule, and HP Blade Server interfaces.
If the product has an embedded PCI Express bus (e.g., a bus which runs between chips on the same circuit board), then
either a mid-bus probe or a multi-lead probe can be used. The mid-bus probe requires a connection footprint (see below)
to be designed into the board. The multi-lead probe allows individual connections to each bus trace on the board.
The Teledyne LeCroy mid-bus probes are 16-channel differential signal probes that meet the demand for high-density
signal access, accuracy and repeatability while providing connector-less attachment to the device under test. They are
based upon the configuration that was initially recommended in the Intel PCI Express Mid-Bus Probing Footprint and
Pinout Revision 1.0 document dated 8/05/03 and the subsequent revisions.
A mid-bus probe is one of the tools that can greatly help engineers
debugging PCI Express buses. A PCI Express mid-bus probing solution
provides direct probing capability of a PCI Express bus at a width of up to
16 lanes. To accommodate a mid-bus probe, a special pad layout is
required to expose the PCI Express differential pairs on the surface of the
target board.
Although not part of the PCI Express specifications, the industry has developed a common mid-bus probe footprint for
Gen1 and Gen2 applications as shown on the right. This footprint is recommended for use with all types of test
equipment including protocol analyzers, logic analyzers and oscilloscopes. The required pad layout can be in x4 (half-
size), x8 (full-size) or x16 (dual full-size) configurations depending on the maximum number of lanes that need to be
probed. All footprint sizes support probing at reduced lane widths (e.g., x1) and lane widths up to the maximum footprint
size. In the photo shown on page 6, the footprint occurs on the target board at "B". Note that this manual documents the
mid-bus footprint used for Gen1 and Gen2 applications; the probe footprint for Gen3 is covered in the PCI Express 3.0
Mid-Bus Probe User Manual.
Teledyne LeCroy makes two versions of mid-bus probes, one for Gen1/2 (2.5 and 5 GT/s data rates) and one for Gen3
(2.5, 5 and 8 GT/s data rates). This manual covers only the Gen2 mid-bus probe. See other user manuals for the other
mid-bus probes.
The Gen2 mid-bus probe is intended for use with the Summit Analyzers and is available with a half-size probe or full size
probe. The half-size probe is shown on page 6. It has a two-strand ribbon cable and a connection header (B). Note that a
half-size footprint supports only up to x4 lane widths.
The part numbers and components of the Teledyne LeCroy Summit T24 Gen2 mid-bus probe kit (which is also compatible
with Gen1) are as follows:
PE081ACA-X Gen2 Mid-Bus Probe, x4 Lane Width, Half-size Module, which includes:
PE013UCA-X iPass x4 to x8 Straight Cable
PE071UIA-X Mid-Bus Pod for Summit T24 (incl. power supply)
PE075ACA-X Mid-bus Probe Cable (x4)
PE014UCA-X Reference Clock Cable
PE076ACA-X Universal Retention Module