
Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
4
3000 X-Series Oscilloscopes Advanced Training Guide
75
21
Set the scope’s timebase to
200.0 µs/div
.
You should now see stable waveform traces on your scope’s display similar
to
. The I
2
C frame that is near the center of the scope’s display,
which is the frame that the scope is triggering on, should be decoded as:
< 29RA FFA 80~A > or < 29RA FFA C0~A >
This particular frame should be interpreted as a Read (R) operation from
address 29 with an acknowledge (A), followed by a data byte equal to FF
with an acknowledge (A), following by a data byte equal to either 80 or C0
without an acknowledge (~A). Let’s now capture a very long stream of I
2
C
data and then manually search through the captured and decoded record.
22
Set the scope’s timebase to
20.00 ms/div
.
23
Press the
[Serial]
front panel key; then press the
Lister
softkey.
24
Press
[Run/Stop]
to stop repetitive acquisitions.
25
Press the
Scroll Lister
softkey; then turn the Entry knob to manually
scroll through the lister table.
As you scroll through the data, note that waveforms “track”. This means
that the frame that the arrow points to in the lister table corresponds to
the waveforms that are positioned at center- screen. If you want to zoom
in on a particular I
2
C frame, either push the Entry knob, or press the
Figure 52 Triggering on I
2
C traffic.