Transcript
Automotive Busses Overview and Testing Challenges using an Oscilloscope Tony Minchell, Applications Engineer, Teledyne LeCroy.
Teledyne Technologies Enabling Technologies for Industrial Growth Markets
Offshore energy & global infrastructure
Machine vision, imaging and factory automation
Analytical and electronic test & measurement
Military C4ISR (Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance)
Aircraft information management
Company Confidential
10/2/2013
2
Marine Instrumentation Splash Mate / Dry Mate Interconnects
Near Surface Current Profiling
Oil in Water Analyzers
Seismic Survey
Motion Sensors
Real Time Data Transfer Navigation & Positioning
Wet Mate Data Transfer Power & Communication Interconnects
Cable Termination Company Confidential
Current and Water Column Velocity Measurement
10/2/2013
3
Test & Measurement Instrumentation Environmental & Chemical Analysis
Electronic Test & Measurement
Company Confidential
10/2/2013
4
Teledyne LeCroy Snapshot
Products
Digital Oscilloscopes (~85%) Protocol Analyzers (~15%)
End Markets
Comp & Cons Elec (35%), Auto-Industrial (25%), Data Storage (15%)
Geographic Markets
1/3 each Americas, EMEA, Asia-Pacific
Locations
Chestnut Ridge NY - HQ, Santa Clara - -Protocol, WW Sales Offices
Employees
~500 Employees:
Financial Metrics
$185M Annual Sales (2012F)
Company Confidential
10/2/2013
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LeCroy Benefits from Teledyne Acquisition Access to the latest in high speed Indium Phosphide
Ability to develop instruments combining Teledyne technology with LeCroy expertise
Backing and support of a large technology company
Company Confidential
10/2/2013
6
LeCroy Innovations Benefit Key Industries Automotive - protocol analysis on physical waveform for automotive data busses
Power – identify and quantify areas of power loss with High Resolution 12-bit instrumentation
Data Storage – early serial data test with specialized measurements
Serial Data – compliance, debug and analysis Optical – high bandwidth instrumentation with optical modulation analysis capabilities
Company Confidential
10/2/2013
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Automotive Evolution
Today
Near future
BUS Overview LIN / SENT
Single-wire CAN
Low Speed CAN
High Speed CAN
FlexRay
Medium Access Control
Master Slave
Contention
Contention
Contention
Time Triggered
Bus Speed
20 Kbps
33 Kbps
125 Kbps
500 Kbps to 1 Mbps
Two 10 Mbps Channel
Error detection (DATA)
8 bit checksum
15 bit CRC
15 bit CRC
15 bit CRC
Three error processing method
Physical Layer
Single wire 12 V
Single Wire 5 V
Twisted pair 5 V
Twisted pair 5 V
Twisted pair
Cost
Low
Low / Medium
Medium
Low / Medium
High
Applications
Sensors/Actuator s (Windows, Door)
Comfort / Convenience
Comfort / Convenience
Powertrain & Comfort / Convenience
Safety / Chassis
Affiliation / Support
LIN Consortium
GMLAN
CAN in Automation
CAN in Automation
FlexRay Consortium
Web Site
www.linsubbus.org
http://auto.ihs.com
www.cancia.org/can
www.cancia.org/can
www.flexray.com
Key System Aspect
Low cost
Selective Wake-up
Fault Tolerant
Main vehicle bus
Deterministic & Fault Tolerant
Industry Standard
Lin 2.1 & J2602
J2411
ISO11898-3
ISO11898-2/-5 J2284
The Structure of Data Analogue – Continuous stream Examples: Vinyl & Gramophone Records, FM / AM Radio, Analogue TV. Low Interference Tolerance
Digital – Non-continuous bursts of digitally encoded data. Examples: Audio CD, DAB Radio, Digital TV. Also Automotive Busses (CAN, LIN, FlexRay, SENT, etc)
High Interference Tolerance Analogue Examples: Audio
Analogue Television
The Structure of Data Digital – Non-continuous bursts of digitally encoded data. 1 or 0 levels only High Interference Tolerance Examples: Audio CD, DAB Radio, Digital TV. Also Automotive Busses (CAN, LIN, FlexRay, SENT, etc)
Non-continuous bursts of digitally encoded data
Continuous Analogue Audio Example
(Heartbreak Hotel – Elvis Presley)
Spaces between bursts of digitally encoded data
Issue 1) Common Mode Noise
Common Mode Noise – Continuous interference stream It’s everywhere Usually low frequency compared to data rate Data is unaffected But Common Mode Noise affects receiving capabilities Errors in receiver system due to wandering data voltage levels
Common Mode Example: Communication Link
Common Mode Waveform (No Data)
Issue 1) Common Mode Noise Common Mode Noise – Continuous interference stream Usually low frequency compared to data rate Data is unaffected But Common Mode Noise affects receiving capabilities Errors in receiver system due to wandering data voltage levels
Solution – Use Differential Waveforms Two identical data streams but with opposite data polarity Common Mode interference the same on each channel Differential circuitry removes common mode noise A B Differential Waveform received
Differential Processing (A minus B)
Clean Waveform
Probing Waveforms with Common Mode Noise Passive Probes – Standard with an Oscilloscope + Low cost
+ Supplied with the Oscilloscope + Robust - No Common Mode Rejection capabilities - Cannot set an event trigger (due to wandering waveforms) - Waveform Math cannot aid trigger issues - Cars are not grounded systems - 2 scope channels required for ‘pseudo’ differential using Math
True Differential Probes – Optional for an Oscilloscope - Higher cost
- Optional for the Oscilloscope (extra cost) ~ Moderately robust (up to several kV)
+ High Common Mode Rejection Ratio
+ Common Mode interference automatically removed + Full triggering capabilities + Only 1 scope channel required + Works successfully in ungrounded systems
Other uses for Differential Probes True Differential Probes – Other uses Voltages across components
“A”
Supports both grounded and floating measurements
“B”
Differential Probes avoid Ground referenced measurements being
Output
upset by alternate ground path Currents in the ground distribution system result in “Ground is not ground” syndrome Moving the ground closer to the device via a single ended probe will result in an alternate ground path and large circulating currents in the probe ground lead
Current Measurements Using a current shunt
0.001 Ohm Shunt
And probe all differential busses, etc. Load Circuit
HDO4000-MS Product Introduction 16x More Resolution, 16x Closer to Perfect Pubic Launch Date October 14, 2103
