Teledyne LeCroy WS3K-Audiobus TD User manual

Instruction Manual

AudioBus

Trigger, Decode, Graph

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Contents

About the AudioBus Options 1

Decode 1
Trigger 1
Graph 1

Serial Decode 2

Bit-level Decoding 2
Logical Decoding 2
Message Decoding 2
User Interaction 2
Decoding Workflow 3
Decoder Set Up 3
Failure to Decode 6
Serial Decode Dialog 6
Reading Waveform Annotations 7
Serial Decode Result Table 8
Searching Decoded Waveforms 13
Decoding in Sequence Mode 14
View and Play Audio 15
Improving Decoder Performance 16
Automating the Decoder 17

Serial Trigger 18

Requirements 18
Restrictions 18
Linking Trigger and Decoder 18
AudioBus Trigger Setup 19
Using the Decoder with the Trigger 21
Saving Trigger Data 21

Technical Support 23

Live Support 23
Resources 23
Service Centers 23

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AudioBus Trigger, Decode, Graph Instruction Manual

About This Manual

Teledyne LeCroy offers a wide array of toolsets for decoding and debugging serial data streams.
These toolsets may be purchased as optional software packages, or are provided standard with some
oscilloscopes.

This manual explains the basic procedures for using serial data decoder and trigger software options.

It is assumed that:

l You have purchased and activated one of the serial data products described in this manual.

l You have a basic understanding of the serial data standard physical and protocol layer

specifications, and know how these standards are used in controllers.

l You have a basic understanding of how to use an oscilloscope, and specifically the Teledyne

LeCroy oscilloscope on which the option is installed. Only features directly related to serial
data triggering and decoding are explained in this manual.

Teledyne LeCroy is constantly expanding coverage of serial data standards and updating software.
Some capabilities described in this documentation may only be available with the latest version of
our firmware. You can download the free firmware update from:

While some of the images in this manual may not exactly match what is on your oscilloscope
display—or may show an example taken from another standard—be assured that the functionality is
identical, as much functionality is shared. Product-specific exceptions will be noted in the text.

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About the AudioBus Options

About the AudioBus Options

AudioBus is a synchronous bus based on three wires which are used to pass multiple channels of
audio data over a single line for use in connecting digital audio devices together.

NXP (formerly Philips Semiconductors) provides a full description of the I2S AudioBus variant in .pdf
format at:

Decode

The Teledyne LeCroy AudioBus options apply software algorithms to extract audio-encoded serial
data information from physical layer waveforms measured on your oscilloscope. The software
decodes the Inter-IC Sound (I2S), Left Justified (LJ), Right-Justified (RJ), and Time Division
Multiplexed (TDM) variants of the protocol. The extracted information is displayed over the actual
physical layer waveforms, color-coded to provide fast, intuitive understanding of the relationship
between AudioBus messages and other, time synchronous events.

Trigger

AudioBus TD implements a serial data trigger that is configurable for I2S, LJ, and RJ variants.
Triggers can be set on specific data patterns in any audio channel, or signal "errors" such as mutes,
clips, and glitches.

Graph

The AudioBus TDG option (trigger, decode and graph) adds View Audio and Play Audio features to
convert the digitally-encoded audio signal into an analog waveform that can be viewed or played aloud
and saved to a playable (.WAV) format, providing intuitive understanding of events in the serial data
signal.

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AudioBus Trigger, Decode, Graph Instruction Manual

Serial Decode

The algorithms described here at a high level are used by all Teledyne LeCroy serial decoders sold for
oscilloscopes. They differ slightly between serial data signals that have a clock embedded in data
and those with separate clock and data signals.

Bit-level Decoding

The first software algorithm examines the embedded clock for each message based on a default or
user- specified vertical threshold level. Once the clock signal is extracted or known, the algorithm
examines the corresponding data signal at the predetermined vertical level to determine whether a
data bit is high or low. The default vertical level is set to 50% and is determined from a measurement
of peak amplitude of the signals acquired by the oscilloscope. For most decoders, it can also be set
to an absolute voltage level, if desired. The algorithm intelligently applies a hysteresis to the rising
and falling edge of the serial data signal to minimize the chance of perturbations or ringing on the
edge affecting the data bit decoding.

Note: Although the decoding algorithm is based on a clock extraction software algorithm
using a vertical level, the results returned are the same as those from a traditional protocol
analyzer using sampling point-based decode.

Logical Decoding

After determining individual data bit values, another algorithm performs a decoding of the serial data
message after separation of the underlying data bits into logical groups specific to the protocol
(Header/ID, Address Labels, Data Length Codes, Data, CRC, Parity Bits, Start Bits, Stop Bits,
Delimiters, Idle Segments, etc.).

Message Decoding

Finally, another algorithm applies a color overlay with annotations to the decoded waveform to mark
the transitions in the signal. Decoded message data is displayed in tabular form below the grid.
Various compaction schemes are utilized to show the data during a long acquisition (many hundreds
or thousands of serial data messages) or a short acquisition (one serial data message acquisition).
In the case of the longest acquisition, only the most important information is highlighted, whereas in
the case of the shortest acquisition, all information is displayed with additional highlighting of the
complete message frame.

User Interaction

Your interaction with the software in many ways mirrors the order of the algorithms. You will:

l Assign a protocol/encoding scheme, an input source, and a clock source (if necessary) to one

of the four decoder panels using the Serial Data and Decode Setup dialogs.

l Complete the remaining dialogs required by the protocol/encoding scheme.

l Work with the decoded waveform, result table, and measurements to analyze the decoding.

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Serial Decode

Decoding Workflow

We recommend the following workflow for effective decoding:

1. Connect your data and strobe/clock lines (if used) to the oscilloscope.

2. Set up the decoder using the lowest level decoding mode available (e.g., Bits).

3. Acquire a sufficient burst of relevant data. The data burst should be reasonably well centered
on screen, in both directions, with generous idle segments on both sides.

Note: See Failure to Decode for more information about the required acquisition

settings. A burst might contain at most 100000 transitions, or 32000 bits/1000 words,
whichever occurs first. This is more a safety limit for software engineering reasons
than a limit based on any protocol. We recommend starting with much smaller bursts.

4. Stop the acquisition, then run the decoder.

5. Use the various decoder tools to verify that transitions are being correctly decoded. Tune the
decoder settings as needed.

6. Once you know you are correctly decoding transitions in one mode, continue making small
acquisitions of five to eight bursts and running the decoder in higher level modes (e.g., Words).
The decoder settings you verify on a few bursts will be reused when handling many packets.

7. Run the decoder on acquisitions of the desired length.

When you are satisfied the decoder is working properly, you can disable/enable the decoder as
desired without having to repeat this set up and tuning process, provided the basic signal
characteristics do not change.

Decoder Set Up

Use the Decode Setup dialog and its protocol-related subdialogs to preset decoders for future use.
Each decoder can use different protocols and data sources, or have other variations, giving you
maximum flexibility to compare different signals or view the same signal from multiple perspectives.

1. Touch the Front Panel Serial Decode button (if available on your oscilloscope), or choose
Analysis > Serial Decode from the oscilloscope menu bar. Open the Decode Setup dialog.

2. From the buttons at the left, select the Decode # to set up.

3. Select the data source (Src 1) to be decoded and the Protocol to decode.

4. If required by the protocol, also select the Strobe or Clock source. (These controls will simply
not appear if not relevant.)

5. Define the bit- and protocol-level decoding on the subdialogs next to the Decode Setup dialog.

Tip: After completing setup for one decoder, you can quickly start setup for the other decoders
by using the buttons at the left of the Decode Setup dialog to change the Decode # .

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AudioBus Trigger, Decode, Graph Instruction Manual

AudioBus Decoder Settings

Audio Subdialog

In Viewing, choose to view/enter data in Binary, Hexadecimal, ASCII or dB formats.

Choose to Annotate (mark on the overlay) All, Left, or Right channels. When AudioBus TDM is the
protocol, the options are All or channels Audio 1 through Audio 8 individually.

Choose to decode using MSB (Most Significant Bit) or LSB (Least Significant Bit) Bit Order. I2S data
is usually transmitted with the most significant bit (MSB) first.

Choose the BCLK Pol. (bit clock polarity), Positive or Negative.

Choose a WS (word select) of Rising or Falling. (This field is FRS in AudioBus TDM.)

Enter the data Start Bit and #Data Bits.

The BCLK Freq. and Audio Freq. will be read from the signal as the decoding is in progress.

AudioBus I2S Variations

In addition to the above, enter the Start Bit to begin counting the decode, generally 0 or 1.

AudioBus TDM Variations

In addition to the above:

Enter the #Bits in Ch(annel).

Choose an FRS (frame select) of Rising or Falling.

Enter the Start Bit to begin counting the decode, generally 0 or 1.

Display Fields

As the decode is run, the Audio Freq(uency) and BCLK Freq(uency) fields are populated for your
reference.

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Serial Decode

Levels Subdialog

Enter the Vertical Level used to determine the edge crossings of the DATA, CLK (Clock) and WS (Word
Select) source signals. This value will be used to determine the bit-level decoding. Level is normally
set as a Percent of amplitude and defaults to 50%. It can alternatively be set as an absolute voltage
by changing the Level Type to Absolute. The set Vertical Level appears as a dotted horizontal line
across the oscilloscope grid. If your initial decoding indicates that there are a number of errors, make
sure that the level is set to a reasonable value.

Note: When Muting a decoded signal or using a Mute Trigger, set your source level types to
Absolute. Adjust the voltage level so it moves to a position above the muted trace on the

display grid.

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AudioBus Trigger, Decode, Graph Instruction Manual

Failure to Decode

Three conditions in particular may cause a decoder to fail, in which case a failure message will
appear in the first row of the summary result table, instead of in the message bar as usual.

All decoders will test for the condition Too small amplitude. If the signal’s amplitude is too small with
respect to the full ADC range, the message “Decrease V/Div” will appear. The required amplitude to
allow decoding is usually one vertical division.

If the decoder incorporates a user-defined bit rate (usually these are protocols that do not utilize a
dedicated clock/strobe line), the following two conditions are also tested:

l Under sampled. If the sampling rate (SR) is insufficient to resolve the signal adequately based

on the bit rate (BR) setup or clock frequency, the message "Under Sampled" will appear. The
minimum SR:BR ratio required is 4:1. It is suggested that you use a slightly higher SR:BR ratio
if possible, and use significantly higher SR:BR ratios if you want to also view perturbations or
other anomalies on your serial data analog signal.

l Too short acquisition. If the acquisition window is too short to allow any meaningful decoding,

the message “Too Short Acquisition” will appear. The minimum number of bits required varies
from one protocol to another, but is usually between 5 and 50.

In all the above cases, the decoding is turned off to protect you from incorrect data. Adjust your
acquisition settings accordingly, then re-enable the decoder.

Note: It is possible that several conditions are present, but you will only see the first relevant
message in the table. If you continue to experience failures, try adjusting the other settings.

Serial Decode Dialog

To first set up a decoder, go to the Decode Setup dialog. Once decoders have been configured, use
the Serial Decode dialog to quickly turn on/off a decoder or make minor modifications to the settings.

To turn on decoders:

1. On the same row as the Decode #, check On to enable the decoder.

As long as On is checked (and there is a valid acquisition), a result table and decoded

waveform appear. The number of rows of data displayed will depend on the Table #Rows

setting (on the Decode Setup dialog).

2. Optionally, modify the:

l Protocol associated with the decoder.

l Data (Source) to be decoded.

3. Check Link To Trigger On to tie this decoder setup to a serial trigger setup.

To turn off decoders: deselect the On boxes individually, or touch Turn All Off.

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Serial Decode

Reading Waveform Annotations

When a decoder is enabled, an annotated waveform appears on the oscilloscope display, allowing you
to quickly see the relationship between the protocol decoding and the physical layer. A colored
overlay marks significant bit-sequences in the source signal: Header/ID, Address, Labels, Data Length
Codes, Data, CRC, Parity Bits, Start Bits, Stop Bits, Delimiters, Idle segments, etc. Annotations are
customized to the protocol or encoding scheme.

The amount of information shown on an annotation is affected by the width of the rectangles in the
overlay, which is determined by the magnification (scale) of the trace and the length of the
acquisition. Zooming a portion of the decoder trace will reveal the detailed annotations.

These overlays appear on an AudioBus waveform or its Zoom trace to highlight key elements of the
decoded signal (not all overlays shown on screen capture):

Annotation Overlay Color

Message Navy Blue (behind other fields)

Left Channel data or
Audio 1 - Audio 8 data (TDM variant)

Right Channel data Green

Decoded waveform. At this resolution, little information appears on the overlay.

Zoom showing annotation details.

Aqua Blue

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AudioBus Trigger, Decode, Graph Instruction Manual

Serial Decode Result Table

When View Decode is checked on the Decode Setup Dialog and a source signal has been decoded
using that protocol, a table summarizing the decoder results appears below the grids. This result
table provides a view of data as decoded during the most recent acquisition, even when there are too
many bursts for the waveform annotation to be legible.

You can export result table data to a .CSV file. See also Automating the Decoder.

Tip: If any downstream processes such as measurements reference a decoder, the result
table does not have to be visible in order for the decoder to function. Hiding the table can
improve performance when your aim is to export data rather than view the decoding.

Table Rows

Each row of the table represents one index of data found within the acquisition, numbered
sequentially. Exactly what this represents depends on the protocol and how you have chosen to
"packetize" the data stream when configuring the decoder (frame, message, packet, etc.).

Note: For some decoders, it is even possible to turn off packetization, in which
case all the decoded data appears on one row of the table.

When multiple decoders are run at once, the index rows are combined in a summary table, ordered
according to their acquisition time. The Protocol column is colorized to match the input source that
resulted in that index.

You can change the number of rows displayed on the table at one time. The default is five rows.

Swipe the table up/down or use the scrollbar at the far right to navigate the table. See Using the

Result Table for more information about how to interact with the table rows to view the decoding.

Table Columns

When a single decoder is enabled, the result table shows the protocol-specific details of the
decoding. This detailed result table may be customized to show only selected columns.

A summary result table combining results from two decoders always shows these columns.

Column Extracted or Computed Data

Index Number of the line in the table

Time Time elapsed from start of acquisition to start of message

Protocol Protocol being decoded

Message Message identifier bits

Data Data payload

CRC Cyclic Redundancy Check sequence bits

Status Any decoder messages; content may vary by protocol

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Serial Decode

Example summary result table, with results from two decoders combined on one table.

When you select the Index number from the summary result table, the detailed results for that index
drop-in below it.

Example summary result table showing drop-in detailed result table.

This extracted audio signal data appears on the detailed result table. Columns can be hidden by

customizing the result table.

Column Extracted or Computed Data

Index
(always shown)

Time Time elapsed from start of acquisition to Start of Frame

Left Left channel data

Right Right channel data

Audio 1- Audio 8
(TDG option only)

Bit Rate/Byte Actual bitrate for this byte, the average BR recomputed by dividing the entire message time

Status List of all errors found in the decoding

Number of the line in the table

Data for audio channels 1 through 8, instead of Left or Right

span by the total number of bytes in the message

Section of typical AudioBus detailed result table.

Using the Result Table

Besides displaying the decoded serial data, the result table helps you to inspect the acquisition.

Zoom & Search

Touching any cell of the table opens a zoom centered around the part of the waveform corresponding
to the index. The Zx dialog opens to allow you to rescale the zoom, or to Search the acquisition. This
is a quick way to navigate to events of interest in the acquisition.

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AudioBus Trigger, Decode, Graph Instruction Manual

Tip: When in a summary table, touch any data cell other than Index and Protocol to zoom.

The table rows corresponding to the zoomed area are highlighted, as is the zoomed area of the
source waveform. The highlight color reflects the zoom that it relates to (Z1 yellow, Z2 pink, etc.). As
you adjust the zoom scale, the highlighted area may expand to several rows of the table, or fade to
indicate that only a part of that Index is shown in the zoom.

When there are multiple decoders running, each can have its own zoom of the decoding highlighted
on the summary table at the same time.

Note: The zoom number is no longer tied to the decoder number. The software tries to match
the numbers, but if it cannot it uses the next zoom that is not yet turned on.

Filter Results

Those columns of data that have a drop-down arrow in the header cell can be filtered:
Touch the header cell to open the Decode Table Filter dialog.

Select a filter Operator and enter a Value that satisfies the filter condition.

Operators Data Types Returns

=, ≠ Numeric or Text Exact matches only

>, ≥, <, ≤ Numeric All data that satisfies the operator

In Range, Out Range Numeric All data within/without range limits

Equals Any (on List),
Does Not Equal Any (on List)

Contains, Does Not Contain Text All data that contains or does not contain the string

Text All data that is/is not an exact match to any full value on

the list. Enter a comma-delimited list of values, no spaces
before or after the comma, although there may be spaces
within the strings.

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Serial Decode

Note: Once the Operator is selected, the dialog shows the format that may be entered in Value

for that column of data. Numeric values must be within .01% tolerance of a result to be
considered a match. Text values are case-sensitive, including spaces within the string.

Select Enable to turn on the column filter; deselect it to turn off the filter. Use the Disable All button
to quickly turn off multiple filters. The filter settings remain in place until changed and can be re­enabled on subsequent decodings.

Those columns of data that have been filtered will have a funnel icon (similar to Excel) in the header
cell, and the index numbers will be colorized.

Example filtered decoder table.

On summary tables, only the Time, Protocol, and Status columns can be filtered.

If you apply filters to a single decoder table, the annotation is applied to only that portion of the
waveform corresponding to the filtered results, so you can quickly see where those results occurred.
Annotations are not affected when a summary table is filtered.

View Details

When viewing a summary table, touch the Index number in the first column to drop-in the detailed
decoding of that record. Touch the Index cell again to hide the details.

If there is more data than can be displayed in a cell, the cell is marked with a white triangle in the
lower-right corner. Touch this to open a pop-up showing the full decoding.

Navigate

In a single decoder table, touch the Index column header (top, left-most cell of the table) to open the
Decode Setup dialog. This is especially helpful for adjusting the decoder during initial tuning.

When in a summary table, the Index column header cell opens the Serial Decode dialog, where you
can enable/disable all the decoders. Touch the Protocol cell to open the Decode Setup dialog for the
decoder that produced that index of data.

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AudioBus Trigger, Decode, Graph Instruction Manual

Customizing the Result Table

Performance may be enhanced if you reduce the number of columns in the result table to only those
you need to see. It is also especially helpful if you plan to export the data.

1. Press the Front Panel Serial Decode button or choose Analysis > Serial Decode, then open the
Decode Setup tab.

2. Touch the Configure Table button.

3. On the View Columns pop-up dialog, mark the columns you want to appear and clear those you
wish to remove. Only those columns selected will appear on the oscilloscope display.

Note: If a column is not relevant to the decoder as configured, it will not appear.

To return to the preset display, touch Default.

4. Touch the Close button when finished.

On some decoders, you may also use the View Columns pop-up to set a Bit Rate Tolerance
percentage. When implemented, the tolerance is used to flag out-of-tolerance messages (messages
outside the user-defined bitrate +- tolerance) by colorizing in red the Bitrate shown in the table.

You may customize the size of the result table by changing the Table # Rows setting on the Decode
Setup dialog. Keep in mind that the deeper the table, the more compressed the waveform display on
the grid, especially if there are also measurements turned on.

Exporting Result Table Data

You can manually export the detailed result table data to a .CSV file:

1. Press the Front Panel Serial Decode button, or choose Analysis > Serial Decode, then open the
Decode Setup tab.

2. Optionally, touch Browse and enter a new File Name and output folder.

3. Touch the Export Table button.

Export files are by default created in the D:\Applications\<protocol> folder, although you can choose
any other folder on the oscilloscope or any external drive connected to a host USB port. The data will
overwrite the last export file saved, unless you enter a new filename.

Note: Only rows and columns displayed are exported. When a summary table is exported, a
combined file is saved in D:\Applications\Serial Decode. Separate files for each decoder are
saved in D:\Applications\<protocol>.

The Save Table feature will automatically create tabular data files with each acquisition trigger. The
file names are automatically incremented so that data is not lost. Choose File > Save Table from the
oscilloscope menu bar and select Decodex as the source.

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Serial Decode

Searching Decoded Waveforms

Touching the Action toolbar Search button button on the Decode Setup dialog creates a 10:1 zoom of
the center of the decoder source trace and opens the Search subdialog.

Touching the any cell of the result table similarly creates a zoom and opens Search, but of only that
part of the waveform corresponding to the index (plus any padding).

Tip: In summary table mode, touch any cell other than Index and Protocol to create the zoom.

Basic Search

On the Search subdialog, select what type of data element to Search for. These basic criteria vary by
protocol, but generally correspond to the columns of data displayed on the detailed decoder result
table.

Optionally:

l Check Use Value and enter the Value to find in that column. If you do not enter a Value, Search

goes to the beginning of the next data element of that type found in the acquisition.

l Enter a Left/Right Pad, the percentage of horizontal division around matching data to display

on the zoom.

l Check Show Frame to mark on the overlay the frame in which the event was found.

After entering the Search criteria, use the Prev and Next buttons to navigate to the matching data in
the table, simultaneously shifting the zoom to the portion of the waveform that corresponds to the
match.

The touch screen message bar shows details about the table row and column where the matching
data was found.

Advanced Search

Advanced Search allows you to create complex criteria by using Boolean AND/OR logic to combine
up-to-three different searches. On the Advanced dialog, choose the Col(umns) to Search 1 - 3 and the
Value to find just as you would a basic search, then choose the Operator(s) that represent the
relationship between them.

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AudioBus Trigger, Decode, Graph Instruction Manual

Decoding in Sequence Mode

Decoders can be applied to Sequence Mode acquisitions. In this case, the index numbers on the
result table are followed by the segment in which the index was found and the number of the sample
within that segment: index (segment-sample).

Example filtered result table for a sequence mode acquisition.

In the example above, each segment was triggered on the occurrence of ID 0x400, which occurred
only once per segment, so there is only one sample per segment. The Time shown for each index in a
Sequence acquisition is absolute time from the first segment trigger to the beginning of the sample
segment.

Otherwise, the results are the same as for other types of acquisitions and can be zoomed, filtered,
searched, or used to navigate. When a Sequence Mode table is filtered, the waveform annotation
appears on only those segments and samples corresponding to the filtered results.

Note: Waveform annotations can only be shown when the Sequence Display Mode is
Adjacent. Annotations are not adjusted when a Sequence Mode summary table is filtered, only
the table data.

Multiple decoders can be run on Sequence Mode acquisitions, but in a summary table, each decoder
will have a first segment, second segment, etc., and there may be any number of samples in each. As
in any summary table, the samples will be interleaved and indexed according to their actual
acquisition time. So, you may find (3-2) of one decoder before (1-1) of another. Filter on the Protocol
column to see the sequential results for only one decoder.

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Serial Decode

View and Play Audio

The View Audio and Play Audio functions (enabled with the TDG option) convert the digitally-encoded
audio signal into an analog waveform that can be viewed or played aloud. This provides an intuitive
way to understand circuit problems causing clipping, glitches, and other anomalies in the audio. It
also helps show the effects of the audio signal before Digital Signal Processing (DSP).

View Audio

View Audio can be performed for up to four audio channels for conventional Left/Right audio, or home
cinema applications (enabled by time division multiplexed audio buses).

On the Audio Track Wizard, set up Math traces for the audio channel you wish to view on the display
grid.

Play Audio

1. Connect external speakers or headphones to your instrument.

2. On the Decode Setup dialog, touch Play Audio.

Saving .WAV Files

To save the converted audio data to a .WAV file for future listening:

1. From the menu bar, choose File > Save Waveform.

2. On the Save Waveform dialog, touch Data Format and select Audio.

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AudioBus Trigger, Decode, Graph Instruction Manual

Improving Decoder Performance

Digital oscilloscopes repeatedly capture "windows in time". Between captures, the oscilloscope is
processing the previous acquisition.

The following suggestions can improve decoder performance and enable you to better exploit the long
memories of Teledyne LeCroy oscilloscopes.

Decode Sequence Mode acquisitions. By using Sequence mode, you can take many shorter
acquisitions over a longer period of time, so that memory is targeted on events of interest.

Parallel test using multiple oscilloscope channels. Up-to-four decoders can run simultaneously, each
using different data or clock input sources. This approach is statistically interesting because multi­channel acquisitions occur in parallel. The processing is serialized, but the decoding of each input
only requires 20% additional time, which can lessen overall time for production validation testing, etc.

Avoid oversampling. Too many samples slow the processing chain.

Optimize for analysis, not display. The oscilloscope has a preference setting (Utilities > Preference

Setup > Preferences) to control how CPU time is allocated. If you are primarily concerned with quickly
processing data for export to other systems (such as Automated Test Equipment) rather than viewing
it personally, it can help to switch the Optimize For: setting to Analysis.

Turn off tables, annotations, and waveform traces. As long as downstream processes such as
measurements or Pass/Fail tests reference a decoder, the decoder can function without actually
displaying results. If you do not need to see the results but only need the exported data, you can
deselect View Decode, or minimize the number of lines in a table. Closing input traces also helps.

Decrease the number of columns in tables. Only the result table rows and columns shown are
exported. It is best to reduce tables to only the essential columns if the data is to be exported, as
export time is proportional to the amount of data exchanged.

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Serial Decode

Automating the Decoder

As with all other oscilloscope settings, decoder features such as result table configuration and export
can be configured remotely.

Configuring the Decoder

The object path to the decoder Control Variables (CVARs) is:

app.SerialDecode.Decoden

Where n is the decoder number, 1 to 4. All relevant decoder objects will be nested under this. Use the
XStreamBrowser utility (installed on the oscilloscope desktop) to view the entire object hierarchy.

The CVAR app.SerialDecode.Decoden.Decode.ColumnState contains a pipe-delimited list of all the
table columns that are selected for display. For example:

app.SerialDecode.Decode1.Decode.ColumnState = "Idx=On|Time=On|Data=On|..."

If you wish to hide or display columns, send the full string with the state changed from "on" to "off", or
vice versa, rather than remove any column from the list.

Timebase, Trigger, and input Channel objects are found under app.Acquisition.

Accessing the Result Table

The data in the decoder Result Table can be accessed using the Automation object:

app.SerialDecode.Decoden.Out.Result.CellValue(line index, column index)(item index, depth index)

n:= 1 to 4

line index:= 1 to K

column index:= 1 to L

item index:= {0, 1, 2} where 0=Value, 1=StartTime, 2=StopTime

depth index:= 1 to M

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AudioBus Trigger, Decode, Graph Instruction Manual

Serial Trigger

TD options provide advanced serial data triggering in addition to decoding. Serial data triggering is
implemented directly within the hardware of the oscilloscope acquisition system. The serial data
trigger scrutinises the data stream in real time to recognise "on-the-fly" the user-defined serial data
conditions. When the desired pattern is recognised, the oscilloscope takes a real-time acquisition of
all input signals as configured in the instrument's acquisition settings. This allows decode and
analysis of the signal being triggered on, as well as concomittant data streams and analog signals.

The serial trigger supports fairly simple conditions, such as "trigger at the begining of any packet,"
but the conditions can be made more restrictive depending on the protocol and the available filters,
such as "trigger on packets with ID = 0x456". The most complex triggers incorporate a double
condition on the ID and data, for example "trigger on packets with ID = 0x456 and when data in
position 27 exceeds 1000".

The trigger and decode systems are independant, although they are seamlessly coordinated in the
user interface and the architecture. It is therefore possible to trigger without decoding and decode
without triggering.

Requirements

Serial trigger options require the appropriate hardware (please consult support), an installed option
key, and the latest firmware release.

Restrictions

The serial trigger only operates on one protocol at a time. It is therefore impossible to express a
condition such as "trigger on CAN frames with ID = 0x456 followed by LIN packet with Adress 0xEBC."

Linking Trigger and Decoder

A quick way to set up a serial trigger is to link it to a decoder by checking the Link to Trigger ("On")
box on the Serial Decode dialog. Linking trigger and decoder allows you to configure the trigger with
the exact same values that are used for decoding the signal (in particular the bit rate), saving the
extra effort needed to re-enter values on the serial trigger set up dialogs.

While the decoder and the trigger have distinct sets of controls, when the link is active, a change to
the bit rate in the decoder will immediately propagate to the trigger and vice-versa.

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AudioBus Trigger Setup

To access the serial trigger dialogs:

l Touch the Trigger descriptor box or choose Trigger > Trigger Setup from the Menu Bar.

l Touch the Serial Type button, and the I2S Standard button.

Then, working from left to right, make the desired selections from the I2S dialog.

Audio Variant

From the buttons at the left, select the variant of the AudioBus standard in use.

Serial Trigger

Source Setup

Each variant has a bus consisting of at least 3 lines: one multiplexed data line (DATA), one bit clock
(BCLK), and one word select line (WS). Enter the source channel for each line.

Enter the Polarity of the DATA signal.

Choose to Sync on the Falling or Rising edge of the signal.

In Threshold, adjust the vertical level for the trigger (even if you have linked the trigger to a pre-set
decoder, this is useful for tuning the trigger to improve the bit-level decoding). The same value is
used for DATA, BCLOCK, and WS signals.

Type

The type of trigger selected determines the remainder of the trigger setup. The setup for each type is
described separately in the following sections. All trigger types require completion of the Audio
Channel setup, as well as the trigger Pattern/Level setup.

Audio Channel

Use these controls to define the audio channel characteristics upon which to base the trigger.

Choose Left or Right Channel.

Choose to use MSB (most-significant bit) or LSB (least-significant bit) Bit Order.

Enter the total # Bits In Channel.

Enter the Start Bit from which to begin the count.

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AudioBus Trigger, Decode, Graph Instruction Manual

Note: This field is disabled for the Audio-RJ variant. The default Start Bit is 8.

Enter the # Data Bitscounted from the Start Bit (you entered) to include in the trigger condition.

Mute Trigger

Mute triggers when the data level is below a specified noise floor for a specified number of frames.

Choose to enter/view data in Dec(imal) or dB (decibel) format.

Enter the Mute Noise Floor below which the data signal must fall and the Duration (# Frames) it must
remain there to produce a trigger.

Clip Trigger

Clip triggers when the data level exceeds a specified clip level for a specified number of frames.

Choose to enter/view data in Dec(imal) or dB (decibel) format.

Enter the Clip Level above which the signal must rise and the Duration (# Frames) it must remain
there to produce a trigger.

Glitch Trigger

Glitch triggers when the rise time between two adjacent audio samples exceeds the specified

threshold.

Choose to enter/view data in Dec(imal) or dB (decibel) format.

In Threshhold, enter the maximum allowable delta between adjacent audio samples.

Rising/Falling Edge Trigger

Rising Edge and Falling Edge trigger when the data level is either rising or falling at the specified

threshold.

Choose to enter/view data in Dec(imal) or dB (decibel) format.

Enter the crossing level in Threshhold.

Data Trigger Setup

Data triggers upon a specific data pattern in the specified audio channel.

Choose to enter/view data in Binary or Hex(adecimal) format.

In Pattern/Levels setup, use Data Condition and Data Value together to create a condition statement
that describes the trigger data pattern. To use a range of values, choose the In Range or Out Range
condition and also enter the Data Value To.

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Serial Trigger

Using the Decoder with the Trigger

A key feature of Teledyne LeCroy trigger and decode options is the integration of the decoder
functionality with the trigger. While you may not be interested in the decoded data per se, using the
decoded waveform can help with understanding and tuning the trigger.

Stop and Look

Decoding with repetitive triggers can be very dynamic. Stop the acquisition and use the decoder tools
such as Search, or oscilloscope tools such as TriggerScan, to inspect the waveform for events of
interest. Touch and drag the paused trace to show time pre- or post-trigger.

Optimize the Grid

The initial decoding may be very compressed and impossible to read. Try the following:

l Increase the height of the trace by decreasing the gain setting (V/Div) of the decoder source

channel. This causes the trace to occupy more of the available grid.

l Change your Display settings to turn off unnecessary grids. The Auto Grid feature

automatically closes unused grids. On many oscilloscopes, you can manually move traces to
consolidate grids.

l Close setup dialogs.

Use Zoom

The default trigger point is at zero (center), marked by a small triangle of the same color as the input
channel at the bottom of the grid. Zoom small areas around the trigger point. The zoom will
automatically expand to fit the width of the screen on a new grid. This will help you to see that your
trigger is occurring on the bits you specified.

If you drag a trace too far left or right of the trigger point, the message decoding may disappear from
the grid. You can prevent "losing" the decode by creating a zoom of whatever portion of the decode
interests you. The zoom trace will not disappear when dragged and will show much more detail.

Saving Trigger Data

The message decoding and the result table are dynamic and will continue to change as long as there
are new trigger events. As there may be many trigger events in long acquisitions or repetitive
waveforms, it can be difficult (if not impossible) to actually read the results on screen unless you
stop the acquisition. You can preserve data concurrent with the trigger by using the AutoSave feature.

l AutoSave Waveform creates a .trc file that copies the waveform at each trigger point. These

files can be recalled to the oscilloscope for later viewing. Choose File > Save Waveform and an
Auto Save setting of Wrap (overwrite when drive full) or Fill (stop when drive full). The files are
saved in D:\Waveforms.

l AutoSave Table creates a .csv file of the result table data at each trigger point. Choose File >

Save Table and an Auto Save setting of Wrap or Fill. The files are saved in D:\Tables.

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AudioBus Trigger, Decode, Graph Instruction Manual

Caution: If you have frequent triggers, it is possible you will eventually run out of hard drive

space. Choose Wrap only if you're not concerned about files persisting on the instrument. If
you choose Fill, plan to periodically delete or move files out of the directory.

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