Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
4
4000 X-Series Oscilloscopes Advanced Training Guide
125
Lab #21: Decoding, Triggering, and Searching on FlexRay Serial Bus
Signals
In this lab you will learn how to set up the scope to decode and trigger on FlexRay
serial bus traffic. In addition, you will learn how to use the scope's automatic
FlexRay Search & Navigation capability, as well as use Segmented Memory
acquisition to capture multiple and consecutive occurrences of a particular
operation. This lab does not provide a tutorial on the FlexRay protocol and
signaling. Also, the FlexRay signal provided is not a complex representation of true
FlexRay traffic; while most FlexRay implementations may have dozens of static
slots and dozens of cycles, our training signal will consist of two slots and two
cycles, for simplicity. To complete this lab, your scope must be licensed with the
FlexRay trigger and analysis option (Option FLX). You can verify the installed
options on your oscilloscope at
[Help] > About Oscilloscope
.
1
Connect the channel-1 probe to the Demo 1 terminal and ground.
2
Press
[Default Setup]
on the scope's front panel.
3
Press
[Help]
; then tap the
Training Signals
softkey.
4
Select and enable the
FlexRay
signal.
5
Set channel-1 to
500 mV/div
.
6
Rotate the trigger level knob to set the trigger level to approximately
-300 mV
.
This is the standard trigger level for FlexRay signals.
7
Set the scope's timebase to
2.0 µs/div
.
You should see on your scope's display what appears to be an un-triggered display
. 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. Let's first
set up the scope to intelligently decode this data stream based on the FlexRay
protocol, and then we will establish a more unique trigger point using FlexRay
triggering.
