PCI Express Gen 1.x, 2.0 and 3.0 Decode Annotation Speeds Validation and Debug

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PCI Express Gen 1.x, 2.0 and 3.0 Decode Annotation Speeds Validation and Debug

PCI Express Decode Annotation, which is available on a wide range of oscilloscopes from LeCroy, provides new capability for hardware and system engineers to simultaneously understand the physical layer and protocol behavior of high-speed PCI Express serial data signals. The new capability provides a link layer protocol decode for up to four PCI Express signals annotated on the oscilloscope physical layer waveform. Combined with LeCroy’s 8b/10b decode annotation tool (a separate option), simultaneous symbol/primitive and protocol level understanding can be achieved. For faster time to insight, all the standard math, measure, cursor, zoom and other analysis tools available in the oscilloscope may be used concurrently.

The new PCI Express Decode Annotation capability has widespread application for all versions of PCI Express. It is especially helpful for the emerging PCI Express Gen 3.0 standard, where new silicon physical layer (PHY) links are beginning to be validated before the standard has been finalized. In the early PHY validation stages, the physical layer signals may not exhibit the desired signal fidelity, and a significant amount of physical layer debug must often occur before a specialized protocol analyzer can be used. In addition, it can be difficult to time correlate protocol analyzer and oscilloscope captures; therefore, interpretation of the information from the two different tools could be more time-consuming and more error prone. By providing the decoded information as an annotation on the physical layer waveform within the oscilloscope, the protocol and physical layer information is synchronized, and permits easy scrolling and review of the captured data, as is often necessary. Thus, interpretation is easier, faster and more reliable in the early PHY validation stage.   

The initial data rate for decoding may be set to the common 2.5, 5, or 8 GT/s. PCI Express Gen 2.0 and Gen 3.0 begin handshaking at lower bit rates, and once the link is established, increase to their maximum data rate. The decode algorithm recognizes the different bit rates and decodes appropriately, and supports modes with and without scrambling enabled. 

Advanced algorithms deconstruct the waveform into protocol information, and then annotate the physical layer waveform on the oscilloscope grid. Decode annotation condenses or expands depending on the time base/zoom ratio setting. Various portions of the protocol are color-coded for intuitive, quick visual understanding of the protocol behavior and easy visibility, even with long acquisitions. For instance, TS1 and SKIPs are color-coded a grayish blue while Electrical Idle, Error, or Unrecognized frames are color-coded red. Other message types are uniquely color-coded.  

To support the large installed base of LeCroy users, the option is available on a wide range of oscilloscope models with real-time bandwidths from 2.5 GHz to 30 GHz  supporting the full range of PCIe users, from Gen 1.x to 3.0. 

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