Teledyne LeCroy FlexRay Trigger, Decode and Physical Layer Test - Manual (Page 25)

O PERATOR ’ S M ANUAL
Pass/Fail Analysis with Measurement Parameters
Pass/Fail analysis using measurement parameters is quite simple to set up and quite powerful. For instance, you
can define a timing measurement, define the limits for the timing measurement, and then run the oscilloscope in a
Normal trigger mode, capturing thousands of measurement events. Then, for example, Pass/Fail can be used to
save the Waveform in the event of a Fail, or send an email in the event of a fail.
Set up Pass/Fail conditions by touching Analysis in the menu bar, then
selecting Pass/Fail Setup. Reference the oscilloscope’s on-line Help
for more detail on pass/fail setup.
ISOLATE AND ANALYZE SERIAL BUS ACTIVITY
The combination of Serial Data Triggering, Decoding, and normal oscilloscope features is a powerful combination
of tools that can make it very easy to find latent Serial Data HW or SW problems in your circuit. No longer is the
oscilloscope a tool just for the hardware engineer. Now the software engineer can also easily visualize the Serial
Data signals and relate it to programming code and operation. The TD options can enable the HW Engineer and
SW Engineer to “speak the same language” when it comes to system debugging and performance checking.
Some common Serial Data analysis needs and methods are discussed below:
Capture Long Pre-Trigger Time
LeCroy oscilloscopes are available with optional very long acquisition memory. For instance, the WaveRunner Xi
Series oscilloscopes can capture up to 12.5 Mpts on 4 channels, or 25 Mpts on 2 channels. If your Serial Data
signals are 1 Mb/s, and you sample at the minimum required and available sample rate (5 MS/s, you would be
able to capture 5 seconds of Serial Data traffic. If you wish, this can be 100% pre-trigger, 100% post-trigger, or
something in between.
1. Adjust Pre-Trigger and Post-Trigger time by adjusting the Delay
knob on the oscilloscope’s front panel.
2. Optimize your Sample Rate or Memory Length by accessing the
Horizontal Dialog in your oscilloscope and selecting either Set Max
Memory mode or Fixed Sample Rate mode.
3. Set Max Memory can be used to decrease the memory usage in
order to not sample at rates you specify as being too high (high
sample rates can slow down the decoding algorithm). Then adjust
your time timebase setting to the length needed to capture the
event.
Note: Make sure your combined timebase and memory length settings do not result in
too low of a sample rate. Otherwise, adequate capture and decode is not performed.
4. It’s common to fix the sample rate to a specified value so you have
the necessary oversampling to capture your Serial Data messages
(at least 4X the bit rate). This also allows for a high enough sample
rate to capture transients you may want to see on your Serial Data
and analog signals (at least 2X the frequency of any expected
transients, preferably 10X).
Reference your oscilloscope’s Online help for more information on these common settings.
FlexRay-TDP-OM-E Rev A
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