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Compliance and Signal
Integrity Analysis of
Automotive Ethernet NetworksSteve Murphy, FAE
September 25, 2019
Agenda – Automotive ENET Compliance and Debug
Introduction
100/1000Base-T1 Compliance testing
Overview of PHY Layer tests, setups, PHY device test modes and registry
control
Signal integrity and PHY Debug
Signal quality issues, debug tools:
Oscilloscope and fixture setup
Software analysis including: Eye Diagrams, eye measurements, equalization
TDR
2
Automotive EthernetSeminar Introduction
Serial Data Links -Typical ADAS System
4
SensorsSensor
Processing
Data Processing
& FusionVehicle Systems
LIDAR
RADAR
GPS
V2VV2I
LeftDPHY TX
Slave
RightDPHY TX
Slave
FrontDPHY TX
Slave
RearDPHY TX
Slave
SerializerDPHY
Master
SerializerDPHY
Master
SerializerDPHY
Master
SerializerDPHY
Master
RX
RX
RX
RXSerial Data Link
Analog Device
Key
Sensor Fusion Module
Memory
LPDDR4
DecisionProcessor
Data In
PCIe Gen410G ENET
Gateway ECU
Engine ECU
ABS ECU
Body ElectronicsECU
InstrumentationECU
Auto ENET
CAN FD
FlexRay
LIN
CAN
DisplayInfotainment
DSI-2
I2C
DPHY TX
SlaveMaster
DPHYRXUSB
HDMI
CSI-2
I2C
CSI-2
I2C
CSI-2
I2C
CSI-2
I2C
Auto ENET
Auto ENET
Auto ENET
CameraPre-Processor /
DeserializerFPD-LINK III
GSMLAPIX
FPD-LINK IIIGSMLAPIX
FPD-LINK IIIGSMLAPIX
FPD-LINK IIIGSMLAPIX
Digital Device
Mixed Signal Device
Serial Data Phy
AVB Ethernet Switch
Auto ENETAuto ENET
Auto ENET
Auto ENET
Automotive Ethernet - Hybrid of 1000Base-T and 100Base-Tx
1000Base-T (Gigabit Ethernet) PAM-5, 5 level, 125 MSps, 65-80 MHz
Full Duplex
Four twisted pairs
100Base-T MLT-3, 3 level, 125 MSps, 65-80 MHz
Half duplex
Two twisted pairs
Automotive Ethernet BroadR-Reach / 100Base-T1
PAM-3, 3 level, 66.67 MSps, 33.33MHz
(allows for lower cost cabling, filtering)
Full Duplex
Single twisted pair
Source: BroadR-Reach Spec Figure 1-1
OABR: Open Alliance BroadR-Reach
1000Base-T1 and 100Base-T1 Employs PAM-3 Signaling
+1
0
-1
Focus for Today is on PHY
Figure 96–1—Architectural Positioning of 100BASE-T1
7
Relationship of 100Base-T1 to
ISO/IEC OSI reference model
and the IEEE 802.3 Ethernet
Model
Automotive Ethernet Organizations
BroadR-Reach
Automotive Ethernet
100Base-T1
1000Base-T1
OABR
(OPEN Alliance
BroadR-Reach)
RTPGE
(Reduced Twisted
Pair Gigabit
Ethernet)
Automotive EthernetPhysical Layer Compliance Testing
100/1000 Base-T1
Where is Electrical Compliance Testing Defined?
Defined at the connector of the transmitter
(MDI connector)MDI = medium dependent interface)
Governed by channel/connector recommendations
PMA Tests: Group 1
Group 1: Electrical Measurements
Group 2: PMA Receive Tests Electrical transmitter tests are
performed with an oscilloscope
There are also MDI tests which are performed using a VNA
MDI Return Loss
MDI Mode Conversion Loss
UNH IOL - Tests and Test Modes: 100BASE-T1 and 1000BASE-T1
12
UNH IOL - Tests and Test Modes: 100BASE-T1 and 1000BASE-T1
13
Test Modes – PHY Register Control Examples – PHY Vendor Utilities
Broadcom Fibercode – FC601
Test Equipment Requirements – 100BASE-T1
1 GHz Oscilloscope with at least 2 GS/s sample rate Teledyne LeCroy recommends 10 GS/s
to provide 10x oversampling for jitter measurements
Oscilloscope with Spectral Analysis capability or Spectrum Analyzer
Disturbing Sine Wave Generator(used for test mode 4 only)
5.4 Vpk-pk at 11.11 MHz
2 BNC cables
2 BNC-SMA adapters
Ethernet Test Fixture
2 SMA cables
2 SMA-BNC Adapters
1 GHz Differential Probe(used for test mode 3 only)
Short Automotive Cable
Vector Network Analyzer
For return loss and common mode
Example Test Setup for PMA Compliance Testing
Close up of Test Setup for PMA Compliance Testing
DUT
Pair A
Differential
Signal
SMA Cables to
oscilloscope RJ45 Breakout Section
Test Setup for the Distortion Test
18
Oscilloscope
AWG (for Vd)
DUT
“Short” Automotive Ethernet CableEthernet Test Fixture
Close up of Test Setup for the Distortion Test – Directional Coupler
DUT
Pair A
Differential
Signal
SMA Cables to
oscilloscope
Distortion Test
Section
Differential Vd from AWG
Directional
coupler:
DUT sees Vd
but very little is
seen by the
oscilloscope
Test Example - Transmitter Timing Master Jitter
Description
This test verifies jitter on transmitted clock is within specified limits
Utilizes PHY Test Mode 2
Measure RMS (root mean squared) of the MDI output jitter over at least
1 ms
Test limit is 50 ps
Transmitter Timing Master Jitter – Methodology
1. Measure Time Interval Error (TIE)
Transmitter Timing Master Jitter – Methodology
2. Create a track of TIE measurements
Transmitter Timing Master Jitter – Methodology
3. Measure rms of TIE track
4. Compare to 50 ps
Test Example - Transmitter Distortion
Description
Test mode 4
Requires access to the TX_TCLK
Disturbing sine wave is sent to
DUT and distortion is measured
Measured using MatLab script
Test limit is 15 mV
Goal
Make sure transmitted signal has
minimal distortion so link partner's
receiver can interoperate with DUT
24
Source: IEEE 100Base-T1 Figure 96-21
MATLAB Code is Provided in the Spec for Peak Distortion Calculation
Any error from ideal reference is counted as distortion
Removes the disturbing sine wave and measures peak distortion at equally spaced phases of the symbol period
Can be run on a separate PC
Teledyne LeCroy embeds MATLAB code in the scope software Doesn’t require a MATLAB license
to process
25
Source: IEEE 100Base-T1
Distortion Calculation
1. Calculate Distortion
2. Compare to 15 mV3. Measure 10 phases
over the UI
Automated Testing and Documentation - Report Example
Teledyne LeCroy QPHY Software
Automotive Ethernet
Signal Quality and Debug
Detecting Signal Quality Link Issues
Signal Quality PHY issues include: Bit errors
Jitter and noise issues
PHY amplitude errors
Rise and Fall time issues
Reflections
Glitches
Runts
Intersymbol Interference
Crosstalk
Problems not detected during compliance testing
Oscilloscope Eye diagram is an overlay of signal transitions, PAM-3 signals, used to characterize system performance
Debug tools separate bi-directional communication of Master and Slave
Equalization shows signal quality from receiver’s perspective
29
Teledyne LeCroy’s Automotive Ethernet Solutions
100Base-T1 and 1000Base-T1
Automated Compliance Testing
QPHY packages
Compliance test fixture
Automotive Ethernet Debug Toolkit
Debug signal quality link communication
issues
Calibrated Signal Separation
TF-AUTO-ENET separates
bidirectional link traffic
30
Automotive Ethernet Eye Pattern Analysis and Debug
Info
31
AUTO ENET Toolkit Setup
Setup Example - Connecting DUTs and Oscilloscope
Connection to oscilloscope through use of SMA cables and SMA / BNC adaptors
Connector boards for attaching both Master and Slave UTP wires
TF-AUTO-ENET fixture that maintains link communication between Master and Slaves and enables uni-directional link quality analysis (separation)
Oscilloscope software tools to Generate eye diagrams and eye
measurements – amplitude and timing
Calibrate TF-Auto-ENET fixture to remove reflections
TDR analysis of signal integrity connections
FFE Equalization to view link quality as receivers
Eye diagram BER contours
TF-AUTO-ENET fixture setup SMA connector boards connect to Port 1 and
Port 2 Inputs
Port 1 and Port 2 outputs connect to scope
33
Separation of Bi-directional Auto ENET Traffic
Maintains link communication
Separates bidirectional link traffic, using two directional couplers, to independently view signals from Master and Slave
Built-in calibration routine, provides superior signal fidelity, labeled as Corrected Eye
Includes TDR analysis of signal integrity connections
34
TF-AUTO-ENET Fixture Calibration
35
Calibration of TF-AUTO-ENET removes reflections for high signal fidelity measurements
Controlled by Auto ENET Debug Toolkit software
Corrected Signal (Left) vs Uncorrected (Right)
Corrected Signal (Blue) vs Uncorrected (Orange)
36
Eye Diagram FFE Equalization
37
Feed Forward Equalization (FFE) provides insight to signal quality from receiver’s
perspective
Controlled by AUTO ENET Debug Toolkit
Uncorrected, Unequalized Eye (Left) vs Uncorrected Equalized (Right)
WavePulser 40iX TDR - High-Speed Interconnect Analyzer
TDR Impedance profile complements S-parameters
WavePulser 40IX intro - customer presentation- June 2019 39
50 Ω Microstrip Filter
Time Domains views:
Impedance profile
detects we are using
connectors with
different quality
Frequency domain views:
S-parameters does not
allow to detect we are
using connectors with
different quality
WavePulser 40iX
combines Impedance
Profile and S-parameters
in a single acquisition
provides unmatched
characterization
S-parameters Impedance Profile
Port 2Port 1
Return Loss
Insertion Loss
frequency
Port 2
Port 1
SMA 2.92 mm
