Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
4
3000 X-Series Oscilloscopes Advanced Training Guide
73
You should see on your scope’s display what appears to be an un- triggered
display of two digital signals similar to
. Your scope is actually
triggering on random rising edges of channel- 1, which is the scope’s
default trigger condition. But these signals are too complex to establish a
unique trigger point using simple edge triggering. The signal being
captured by channel- 1 is an I
2
C serial clock signal (SCL), and the signal
being captured by channel- 2 is an I
2
C serial data signal (SDA). Let’s first
set up the scope to intelligently decode this data stream based on the I
2
C
protocol, and then we will establish a more unique trigger point using I
2
C
triggering.
12
Press the
[Serial]
front key.
13
Press the
Mode
softkey; then select the
I
2
C
serial decode mode using the
Entry.
14
Press the
Signals
softkey and verity that
SCL
is defined as channel- 1,
and that
SDA
is defined as channel- 2 (default conditions).
15
Press the
(Back) front panel button (above power switch) to return
to the previous menu.
16
Press the
Addr Size
softkey and verify that
7 Bit
is selected.
17
Press the
Lister
softkey; then select to show a list of
Serial 1 (I
2
C)
using
the Entry knob.
Figure 50 Capturing I
2
C clock and data while triggering on an edge of the clock
(channel-1).
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