Recently, we introduced the I3C PurVue Analyzer™ feature for the SV4E-I3C I3C Test and Debug Module. This feature is a completely embedded real-time oscilloscope that works closely with the protocol analyzer and exerciser cores to enable incredibly sophisticated measurement features. One of the main reasons we created this real-time oscilloscope was to help our customers debug the complex I3C protocols. We recognized that engineers needed an oscilloscope, but we also recognized that conventional benchtop oscilloscopes were not going to do the job. Read on to learn why!
Probes Are Antennas
One of the most frustrating aspects of using conventional benchtop real-time oscilloscopes is the need to attach active probes to signals being measured. Whether engineers know it or not, every time they attach a wire (such as an active probe) to their system, they are creating an antenna! And this antenna not only confuses the measurements, but it can also affect the protocol analyzer transitions that they are trying to debug in the first place. Referring to the figure below, two oscilloscope screens are shown, and they both show the typical “probed” waveforms that engineers must grapple with. Namely, some of the ringing in these digital waveforms is due to the system under test itself, but some is completely extraneous! For example, the highlighted areas are radio frequency spurs being “picked up” by the antennas created by the probe. These are most likely due to neighboring WIFI or cellular signals on the engineers’ own smartphone.
Most engineers get confused by these signal artefacts, and it takes experience and further debugging to isolate them. More importantly, these signal artefacts often make it difficult to make proper electrical measurements for the purposes of characterization.
On the other hand, by embedding the real-time oscilloscope into the SV4E-I3C, we completely eliminated the need for an extra set of probes. The result is much more pristine waveforms as shown in the following figure.
The top waveform is the SDA line measured using the I3C PurVue Analyzer, and the bottom waveform is the same signal that is simultaneously probed using a conventional real-time oscilloscope. As can be seen, the external scope measurement exhibits way more noise.
General Purpose Probes Are Not Always Accurate
Because of their general-purpose nature, sometimes active probes do not always perform in an ideal way for all applications. For example, a high-frequency active probe is often optimized for low-impedance systems, and it might struggle when measuring an I3C signal. Referring to the figure below, we see the same signal measured simultaneously using the I3C PurVue Analyzer and a conventional benchtop real-time oscilloscope. As can be seen, the I3C PurVue Analyzer has a flatter response and generally produces a more accurate representation of the signal under test.
Exact Time Correlation With Protocol Data
Finally, the I3C PurVue Analyzer is a real-time oscilloscope that works in conjunction with the internal protocol analyzer of the SV4E-I3C. This means that it provides exact time-correlated measurements between the analog domain and the digital domain. This is by far the easiest way to debug an I3C system.
In our quest for providing the best user experience for our customers, we recognized that we had to create a real-time oscilloscope. More importantly, we recognized that we had to make this oscilloscope work seamlessly with the rest of the SV4E-I3C I3C Test and Debug Module. The result was the highly innovative I3C PurVue Analyzer!