I2S Triggering and Serial Decode 29
Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide 459
3 Press the Trigger Setup softkey to open the I
2
S Trigger Setup Menu.
4 Press the Audio softkey; then, turn the Entry knob to choose to trigger on Left
channel events, Right channel events, or events that occur on Either channel.
5 Press the Trigger softkey and choose a qualifier:
• Equal — triggers on the specified audio channel's data word when it equals
the specified word.
• Not equal — triggers on any word other than the specified word.
• Less than — triggers when the channel's data word is less than the specified
value.
• Greater than — triggers when the channel's data word is greater than the
specified value.
• In Range — enter upper and lower values to specify the range in which to
trigger.
• Out of Range — enter upper and lower values to specify range in which trigger
will not occur.
• Increasing value — triggers when the data value is increasing over time and
the specified value is met or exceeded. Set Trigger >= to the data value that
must be reached. Set Armed <= to the value to which the data must fall
before the trigger circuit is re-armed (ready to trigger again). These settings
are made in the current menu when Base is Decimal or in the Bits submenu
when the Base is Binary. The Armed control reduces triggers due to noise.
This trigger condition is best understood when the digital data transferred
over the I2S bus is considered in terms of representing an analog waveform.
The figure below shows a plot of sample data transmitted over an I2S bus for
one channel. In this example, the oscilloscope will trigger at the 2 points
shown since there are two instances in which the data increases from a value
below (or at) the "Armed" value to a value greater than (or equal to) the
specified "Trigger" value.
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