CAN Critical Parameters and Setup Considerations for Module Level EMC Testing Jim Lawlis Ford Motor Company Network Communications 1/19/2005.

CAN Critical Parameters CAN Critical Parameters and Setup Considerations and Setup Considerations

for Module Level EMC for Module Level EMC TestingTesting

Jim LawlisJim LawlisFord Motor CompanyFord Motor Company

Network CommunicationsNetwork Communications1/19/20051/19/2005

1/19/20051/19/2005 Jim Lawlis - Ford Motor CompanyJim Lawlis - Ford Motor Company 22

AgendaAgenda CAN Protocol Critical ParametersCAN Protocol Critical Parameters CAN Bit TimingCAN Bit Timing Load Box Termination, CAN OptionsLoad Box Termination, CAN Options Load Box ExperimentLoad Box Experiment Special Considerations for Optical Special Considerations for Optical

RepeatersRepeaters Diagnosing IssuesDiagnosing Issues CAN Emission ReductionCAN Emission Reduction


CAN Protocol Critical for CAN Protocol Critical for Communication ParametersCommunication Parameters

ArbitrationArbitration• Oscillator ToleranceOscillator Tolerance• All delays need to be counted twiceAll delays need to be counted twice

Note: Choke Delays Count 4 TimesNote: Choke Delays Count 4 Times

RxTx

TxRx

CAN H

CAN L

Transceiver A Transceiver B

Choke A Choke B


Propagation DelaysPropagation Delays Communication MediaCommunication Media

• Number of Nodes Number of Nodes HS CAN – 16, MSCAN - 32HS CAN – 16, MSCAN - 32

• Capacitance on each NodeCapacitance on each Node 100pF to 130pF100pF to 130pF

• Wire LengthWire Length HS CAN 30 MetersHS CAN 30 Meters MS CAN 50 Meters MS CAN 50 Meters

• Bus SpeedBus Speed Twisted Pair 5.5nS/MTwisted Pair 5.5nS/M Twisted pair With 16 Nodes 6.6nS/MTwisted pair With 16 Nodes 6.6nS/M Twisted Pair with 32 Nodes 8.0nS/MTwisted Pair with 32 Nodes 8.0nS/M


CAN Load Box ConfigurationCAN Load Box Configuration

CAN Bit Timing SettingsCAN Bit Timing Settings Monitor ModeMonitor Mode Load Box TerminationLoad Box Termination Data Monitoring – Need to Check the Data Monitoring – Need to Check the

Data, Not Just that Can Traffic is Data, Not Just that Can Traffic is PresentPresent

Monitor Error Frames/Bus offMonitor Error Frames/Bus off


CAN Bit Timing BasicsCAN Bit Timing Basics

The CAN bitThe CAN bit Measuring Total DelaysMeasuring Total Delays J2284 equationsJ2284 equations The Bit Timing SpreadsheetThe Bit Timing Spreadsheet


The CAN BitThe CAN Bit1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

SJW

1 Sync Seg = 12 to 12 tSEG1 = 1113 to16 tSEG2 = 4

SJW = 3


Measuring Total DelaysMeasuring Total Delays

Measure from the TX of one to the Measure from the TX of one to the RX of an identical Module.RX of an identical Module.

RxTx

TxRx

CAN H

CAN L

Transceiver A Transceiver B

Choke A Choke B


J2284 EquationsJ2284 Equations

Created by Karl Overberg of Ford and Created by Karl Overberg of Ford and Dr. Dietmayer of PhilipsDr. Dietmayer of Philips

Bench Validated with Ford internally Bench Validated with Ford internally Designed ModulesDesigned Modules

Vehicle Validated on a Fleet Vehicle Validated on a Fleet Consisting of Police Vehicles, High Consisting of Police Vehicles, High End Ford Vehicles, Heavy TruckEnd Ford Vehicles, Heavy Truck


The Bit Timing SpreadsheetThe Bit Timing SpreadsheetfBIT tBIT delta f tPROPmax tBUSmax tBUS/m LBUSmax tRXmax tTXmax tCHOKmax tLOGCmax tREPEATmax

5.00E+05 2.00E-06 0.004 1.22E-06 2.21E-07 6.60E-09 33.5 5.00E-08 2.80E-07 0.00E+00 6.00E-08 0.00E+00

tQ BIT NtQ tPROPmin tSJWmin tSJWmin tSJWmin tSEG2min tSEG2min tSEG2max tSEG2max tSEG2max Params

Eqn 9) Eqn 13) Num tQ Eqn iv.) Num tQ Eqn 21) Eqn 27) Num tQ OK?

9.09E-08 22 5.00E-08 1.61E-07 2E-07 3 1.82E-07 3 5.8E-07 5.14E-07 5 OK 9.52E-08 21 5.00E-08 1.61E-07 2.04E-07 3 1.9E-07 3 5.8E-07 5.1E-07 5 OK 1.00E-07 20 5.00E-08 1.61E-07 2.09E-07 3 2E-07 3 5.8E-07 5.05E-07 5 OK 1.05E-07 19 5.00E-08 1.61E-07 2.14E-07 3 2.11E-07 3 5.8E-07 5E-07 4 OK 1.11E-07 18 5.00E-08 1.61E-07 2.2E-07 2 2.22E-07 2 5.8E-07 4.94E-07 4 OK 1.18E-07 17 5.00E-08 1.61E-07 2.26E-07 2 2.35E-07 2 5.8E-07 4.88E-07 4 OK 1.25E-07 16 5.00E-08 1.61E-07 2.34E-07 2 2.5E-07 2 5.8E-07 4.8E-07 3 OK 1.33E-07 15 5.00E-08 1.61E-07 2.42E-07 2 2.67E-07 2 5.8E-07 4.72E-07 3 OK 1.43E-07 14 5.00E-08 1.61E-07 2.51E-07 2 2.86E-07 2 5.8E-07 4.62E-07 3 OK 1.54E-07 13 5.00E-08 1.61E-07 2.62E-07 2 3.08E-07 2 5.8E-07 4.51E-07 2 OK 1.67E-07 12 5.00E-08 1.61E-07 2.75E-07 2 3.33E-07 2 5.8E-07 4.39E-07 2 OK 1.82E-07 11 5.00E-08 1.61E-07 2.9E-07 2 3.64E-07 2 5.8E-07 4.23E-07 2 OK 2.00E-07 10 5.00E-08 1.61E-07 3.08E-07 2 4E-07 2 5.8E-07 4.05E-07 2 OK 2.50E-07 8 5.00E-08 1.61E-07 3.58E-07 2 5E-07 2 5.8E-07 3.55E-07 1 **FAIL**


CAN Monitor Only Load BoxesCAN Monitor Only Load Boxes

Note: CAN is an all Node ACK or Note: CAN is an all Node ACK or NACK ProtocolNACK Protocol

You may think you are only You may think you are only Monitoring. Unless the tool has a Monitoring. Unless the tool has a Monitor Only Option and it has been Monitor Only Option and it has been Enabled, the load box is Participating Enabled, the load box is Participating in Communication!!!in Communication!!!


Termination MethodsTermination Methods

Termination MethodsTermination Methods• Terminated NodesTerminated Nodes

Standard TerminationStandard Termination Split TerminationSplit Termination

• Test Tool TerminationTest Tool Termination A/C Termination (ISO 15765, Part 4, section A/C Termination (ISO 15765, Part 4, section

9.4.1.3)9.4.1.3)


Load Box TerminationLoad Box Termination

Terminated Nodes Non-Terminated Nodes

~ 60 Ohm 1%

~ 60 Ohm 1% ~ 60 Ohm 1%

~ 60 Ohm 1%

4.7nF 4.7nF


Chamber Set-UpChamber Set-Up

Tool is Configured Tool is Configured

Delays Have been identified/CheckedDelays Have been identified/Checked

How do We Connect the Load Box to How do We Connect the Load Box to the set up in the chamber?the set up in the chamber?


CAN Load Box ExperimentCAN Load Box Experiment Parameters That Need to be DefinedParameters That Need to be Defined

• Board to Case (A/C, D/C, Open)Board to Case (A/C, D/C, Open)• Case to ground plane (On Ground Plane, 5 cm Case to ground plane (On Ground Plane, 5 cm

Above ground plane)Above ground plane)• Network Load box to system Load box power Network Load box to system Load box power

wiring (On Ground Plane, 5 cm Above Ground wiring (On Ground Plane, 5 cm Above Ground Plane)Plane)

A full Factorial Experiment was run A full Factorial Experiment was run because it provides the most information because it provides the most information and 12 runs were possibleand 12 runs were possible


Experiment SetupExperiment SetupY Performance = X1 X2 X3X1 = Routing (5cm or Ground Plane)X2 = Case to Table (5cm or Ground Plane)X3 = Board to Case (AC, DC, or Open)

DUT

LoadBox

Metal Case

X2

GroundPlane

CAN Tool

X3

Power

Ground

CAN_H

CAN_LMake these lines

as short as possible

X1


Experiment AnalysisExperiment Analysis

Previous Experience determined the Previous Experience determined the worst case Load Box Setup noise was worst case Load Box Setup noise was observed in the Vertical BICON 30 to observed in the Vertical BICON 30 to 200Mhz 200Mhz

Area of violations above the limit line Area of violations above the limit line were measured and calculated for were measured and calculated for each testeach test

The Best Performance was IdentifiedThe Best Performance was Identified


DOE Test MatrixDOE Test Matrix

Run Order Power Routing Case to Table Board to Case

1 GND GND A/C

2 5cm GND A/C

3 GND 5cm A/C

4 5cm 5cm A/C

5 GND GND D/C

6 5cm GND D/C

7 GND 5cm D/C

8 5cm 5cm D/C

9 GND GND Open

10 5cm GND Open

11 GND 5cm Open

12 5cm 5cm Open


Experiment DataExperiment Data

PEAK

FREQUENCY [MHz]

EMISSION LEVEL[ dBuV/Meter]

30 100 200

0

20

40

60

80CISPR 25 RE NB VERT BICON

J Lawlis Ford Test #5 Power Routing on GND Board to Case GND is DC Case Bonded to GND J. Stonier

11 Mar 2003 12:31:18UL EMC Test Lab, Detroit


Data Processing Data Processing

Normality of the Data and ResidualsNormality of the Data and Residuals Minitab DOE AnalysisMinitab DOE Analysis Multi-Variable ChartMulti-Variable Chart Interaction PlotInteraction Plot Main Effects PlotMain Effects Plot


Normality of DataNormality of Data


Normality of ResidualsNormality of Residuals


Minitab DOE AnalysisMinitab DOE AnalysisGeneral Linear Model: Data 2 versus Power Routin, Case to Tabl, ...General Linear Model: Data 2 versus Power Routin, Case to Tabl, ...Factor Type Levels Values Factor Type Levels Values Power Ro fixed 2 GND 5cmPower Ro fixed 2 GND 5cmCase to fixed 2 GND 5cmCase to fixed 2 GND 5cmBoard to fixed 3 AC DC OpenBoard to fixed 3 AC DC OpenAnalysis of Variance for Data 2, using Adjusted SS for TestsAnalysis of Variance for Data 2, using Adjusted SS for TestsSource DF Seq SS Adj SS Adj MS F PSource DF Seq SS Adj SS Adj MS F PPower Ro 1 675.00 675.00 675.00 8.70 0.098Power Ro 1 675.00 675.00 675.00 8.70 0.098Case to 1 280.33 280.33 280.33 3.61 0.198Case to 1 280.33 280.33 280.33 3.61 0.198Board to 2 296.17 296.17 148.08 1.91 0.344Board to 2 296.17 296.17 148.08 1.91 0.344Power Ro*Case to 1 320.33 320.33 320.33 4.13 0.179Power Ro*Case to 1 320.33 320.33 320.33 4.13 0.179Power Ro*Board to 2 420.50 420.50 210.25 2.71 0.270Power Ro*Board to 2 420.50 420.50 210.25 2.71 0.270Case to*Board to 2 2276.17 2276.17 1138.08 14.67 0.064Case to*Board to 2 2276.17 2276.17 1138.08 14.67 0.064Error 2 155.17 155.17 77.58Error 2 155.17 155.17 77.58Total 11 4423.67Total 11 4423.67


Multi-Variable ChartMulti-Variable Chart


Interactions PlotInteractions Plot


Main Effects PlotMain Effects Plot


Experiment ResultsExperiment Results

DUTLoadBox

Metal Case

GNDGroundPlane

See EMC ES-XW7T-1A278-A(X)(X): Recent Version

CAN Tool

Board to Case DC

GND

Power

Ground

CAN_H

CAN_LMake these lines

as short as possible


Monitoring CAN through Optical Monitoring CAN through Optical RepeatersRepeaters

The Signal Delay of a Typical Optical The Signal Delay of a Typical Optical Repeater (wire to optical to wire) will Repeater (wire to optical to wire) will be ~300nsbe ~300ns

This does not include the signal delay This does not include the signal delay through the Optical Cable through the Optical Cable ~5.0ns/meter.~5.0ns/meter.


Network Length Penalty for Optical Network Length Penalty for Optical Repeaters Repeaters

Assume Tool uses a CrystalAssume Tool uses a Crystal Fast Tool Transceiver (Combined RX Fast Tool Transceiver (Combined RX

and TX delays less than 255ns vs. and TX delays less than 255ns vs. 330ns)330ns)

Communication and Arbitration can Communication and Arbitration can be Guaranteed through 24 meters be Guaranteed through 24 meters Tool to Furthest ModuleTool to Furthest Module


Diagnosing IssuesDiagnosing Issues

No Substitute for an OscilloscopeNo Substitute for an Oscilloscope Just turning off CAN communication will Just turning off CAN communication will

not tell the story. You need to rerun with not tell the story. You need to rerun with the TX pin shorted to the dominant state. the TX pin shorted to the dominant state. This shows the noise on the 5 Volt feed as This shows the noise on the 5 Volt feed as well as on the ground of the node.well as on the ground of the node.

CAN tools need to make assumptionsCAN tools need to make assumptions Advantages of monitoring the Common Advantages of monitoring the Common

Mode and Differential Mode signalsMode and Differential Mode signals


CAN Radiated Emission Reduction CAN Radiated Emission Reduction MethodsMethods

Overall GoalOverall Goal Communication Bus Noise will always Communication Bus Noise will always

be Low Frequency. High Frequency be Low Frequency. High Frequency Noise is due to Setup issuesNoise is due to Setup issues

Ferrites Ferrites ChokesChokes Split TerminationSplit Termination


Base Line RodBase Line Rod


Ferrites RodFerrites Rod


Choke 51uH RodChoke 51uH Rod


Split Termination RodSplit Termination Rod

CAN Critical Parameters and Setup Considerations for Module Level EMC Testing Jim Lawlis Ford Motor Company Network Communications 1/19/2005.

Documents

nsm slide

nf slide

timing load box termination

timing spreadsheet slide

karl overberg of ford

load box configuration

load box experiment

heavy truck slide