4 Triggering
116 InfiniiVision Oscilloscopes User’s Guide
As you press the SCL softkey (or rotate the Entry knob), the SCL label for the source
channel is automatically set and the channel you select is shown in the upper-right
corner of the display next to “I
2
C”.
7 Set the trigger levels for the SCL and SDA signals to the middle of the signals:
• If your I
2
C signals are connected to analog channels, press the SCL softkey and
rotate the Trigger Level knob, then press the SDA softkey and rotate the Trigger
Level knob.
• If your I
2
C signals are connected to digital channels (this applies to MSO model
oscilloscopes only), press the [D15-D0] key and the Thresholds softkey to access
the threshold level setting softkeys and set the thresholds to the approximate
middle of the signals.
8 Choose 7-bit or 8-bit address size. Use 8-bit address size to include the R/W bit as part
of the address value, or choose 7-bit address size to exclude the R/W bit from the
address value.
9 Connect an oscilloscope channel to the SDA (serial data) line in the device under test,
then set the SDA data channel softkey to that channel.
10 As you press the SDA softkey (or rotate the Entry knob), the SDA label for the source
channel is automatically set and the channel you select is shown in the upper-right
corner of the display next to “I
2
C”.
Adjust the trigger level for the selected analog channel by turning the Trigger Level
knob. Press the [D15-D0] key and select Thresholds to set the threshold level for
digital channels. The value of the trigger level or digital threshold is displayed in the
upper-right corner of the display.
Data needs to be stable during the whole high clock cycle or it will be interpreted as a
start or stop condition (data transitioning while the clock is high).
11 Return to the previous menu; then, press the Trigger: softkey to select one of the
following I
2
C trigger conditions:
• Start Condition — The oscilloscope triggers when SDA data transitions from high
to low while the SCL clock is high. For triggering purposes (including frame
triggers), a restart is treated as a start condition.
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