Technical data

Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs 4
4000 X-Series Oscilloscopes Advanced Training Guide 81
You should see on your scope’s display what appears to be an un- triggered
display of two digital signals similar to Figure 50. 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 Tap the Mode softkey; then select the I
2
C serial decode mode.
14 Tap the Signals softkey and verity that SCL is defined as channel- 1, and
that SDA is defined as channel- 2 (default conditions). Set each
Threshold level to ~1.3 V if not set already.
15 Press the (Back) front panel button (above power switch) to return
to the previous menu.
16 Tap the Addr Size softkey and verify that 7 Bit is selected.
Figure 50 Capturing I
2
C clock and data while triggering on an edge of the clock
(channel-1).
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