Teledyne LeCroy Serial Data Debug Solutions - Manual (Page 160)

Serial Data Debug Solutions
160 919586 RevA
PCIEbus Decode Examples (on page 171). The capture was made with a high impedance differential probe at the
add-in card’s driver chip, both for its TX and RX. Do not capture in the middle of the bus (at the PCIE connector)
as reflections may seriously degrade the signal. Also, we used the FFE in the LeCroy Eye Doctor II software
option package to equalize this signal, to further “open the eye.” Signals traversing a significant length of FR4
(printed circuit board material) and coming through a PCIEbus D may show significant degradation at 5 GT/s to
warrant some equalization, depending on the quality of the probe and where it was connected. At 8 GT/s,
equalization is most definitely required, as it is in 8 GT/s PCIe receivers.
An oscilloscope cannot automatically determine if the signal is inverted and compensate like real receivers do.
Therefore, the PCIEbus Decoder tries to parse the signal supplied – it has no choice because, as in the figures
showing speed change, the capture may begin long after link initialization. Therefore it is important to give the
decoder a signal with correct polarity. If the decode table shows lots of UNRECOGNIZED and single bytes of IDL
(basically junk) then the signal probably needs to be inverted.
If the signal is captured with the wrong polarity, it can easily be corrected later. If the capture is two single-
ended waveforms, then just try both subtraction orders; one of them is correct. If the signal is captured using a
differential probe, invert it (if necessary) and refer to the Polarity Correction (on page 195) topic.
Note: Ask your local LeCroy representative for more information about any Serial Data Debug Solution
Protocols or Toolkits using the Contact LeCroy for Support (on page 199) topic.
FibreChannel Decode Setup Detail
For general information about using controls shown on the main Serial Decode dialog, refer to Accessing The D
and TD Supported Protocol Toolsets (on page 13).
F IBRE C HANNEL D ECODER AND E XPORTER R IGHT -H AND D IALOGS
Access the Serial Decode dialog by touching Analysis → Serial Decode on the menu bar.
Touch the corresponding Setup... button for your decode. The Decode Setup... along with corresponding right-
hand dialogs are shown.
FibreChannel Decoder Right-Hand Dialog
The FibreChDecoder right-hand dialog provides detailed controls and setup conditions as follows:

Select a Bus Speed value. Choices include 1.0625, 2.125, 4.25, 8.5, and 14.025 Gbps.

Configure the Probe Selection control based on whether you're using One Differential Probe or Two
Single Ended Probes.

Mark the Show Subfields and/or Has FEC checkboxes as desired.