Automotive Ethernet Test Solution
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The Tektronix 5-CMAUTOEN solution provides the instruments and tools to fully address early validation and debug requirements and fully automated compliance test software for 100BASE-T1 and BroadR-Reach standards. The integration of automotive Ethernet technology has placed greater demands on comprehensive design validation to ensure interoperability between multiple ECUs and devices that will perform reliability in demanding environments. A complete testing solution is a necessity in meeting strict compliance tests and having greater confidence in design margins operating under real world conditions.
Validation and debug
Validation and debugging can easily be accomplished early in the design process and ahead of final compliance testing by using the 5 Series MSO oscilloscope. The oscilloscope’s standard measurement set, along with the optional 5-DJA Advanced Jitter and Timing Analysis software, supports several of the key compliance tests including:
- Clock frequency and transmitter amplitude with histogram and trend analysis
- Positive and negative droop measurements
- Full characterization of jitter performance including TIE and histogram profiles
- Eye diagram analysis of PAM3 signals
This type of early testing increases the likelihood of passing compliance tests, while allowing more complete characterization and determination of design margins. Master and slave jitter measurements can be particularly challenging given the tight compliance limits and the need to eliminate any possible sources of random or deterministic jitter.
Transmitter Master Jitter analysis showing 30.68 ps Time Interval Error (TIE) value using 5 Series MSO measurements and option 5-DJA measurements
Susceptibility to various sources of interference is a concern for reliable network communication between master and slave devices. Confirmation of reliable operation and identification of possible sources of interference or error conditions can be difficult to distinguish given the use of PAM3 signaling.
Eye pattern analysis is a proven technique to evaluate long data streams of complex communication signals. Configuring the oscilloscope with the Advanced Jitter and Eye Analysis software (option 5-DJA) provides capabilities to debug and execute measurements of jitter, timing, and eye diagrams completely.
Analysis of transmitter PAM3 channel injected with a 11.11 MHz disturber signal using 5 Series MSO measurements and option 5-DJA measurements
Automated Automotive Ethernet compliance testing
Physical layer compliance tests have been defined to ensure interoperability between different designs and hardware vendors. These requirements have been expanded and now cover Automotive Ethernet BroadR-Reach V3.2 and IEEE 802.3bw™ (100BASE-T1). For electrical signaling, there are specific tests defined for the Physical Media Attachment (PMA) and, as part of Group 1, focuses primarily on the transmitter. Automotive Ethernet testing requires an oscilloscope with a minimum of 1 GHz bandwidth. Supported tests include:
- Maximum Output Droop
- Timing Jitter (master/slave)
- Power Spectral Density (PSD)
- Clock Frequency
- MDI Return Loss
- Peak Differential Output
The Tektronix Automotive Ethernet test solution provides automated compliance support for IEEE 802.3bw™ (100BASE-T1) and BroadR-Reach V3.2 requirements. The automated compliance solution includes test software that runs on a 1 GHz or greater Windows-OS Tektronix oscilloscope to perform all physical layer (PHY) transmitter compliance tests.
The compliance software allows for complete or selective testing of any of the transmitter electrical specifications including complete oscilloscope control of the required setups. Software setup flexibility allows for design validation, margin analysis, and repeatable compliance testing while reducing instrument setup difficulties. Additionally, the software can generate a comprehensive date-stamped test report with pass/fail results, display waveforms, and data plots.
The TekExpress Automotive Ethernet setup menu
The Automotive Ethernet compliance software allows selection of all or any of the specific tests through a simple Setup menu. Software navigation follows a logical workflow for quick test setups, changes, and review of test results.
Test setup configurations vary greatly from connections to the device under test, probing, test fixtures, calibration, and use of the oscilloscope and signal generator. To aid the users, the Automotive Ethernet software provides setup instructions for each test, with images and reference illustrations, to ensure the correct setup.
The Automotive Ethernet compliance software requires a Tektronix 5 Series MSO oscilloscope with Option 5-WIN or SUP5-WIN (Microsoft Windows 10). Since it operates as a Windows application, the software shares the oscilloscope display. For optimum operation, the recommended configuration is to add a PC display monitor to display the compliance software and test reports separately from the oscilloscope screen.
Displaying the compliance software on a separate monitor for easier results analysis
Conducting each test requires configuring the transmitter for specific operating modes using specialized software from the device supplier. Once the transmitter is correctly configured, along with the proper test fixtures and probing, configure the Automotive Ethernet software setup to match the specific test of interest. After test selection, the software will guide the user when needed and perform all the necessary instrument setups. For the Distortion and Return Loss tests, this can include setup of the signal generator required to conduct these tests.
Performing the distortion test requires being able to reference the actual PHY reference clock used to synch the oscilloscope and signal generator. Under certain circumstances, it may not be possible to directly access this clock. In these situations, the Automotive Ethernet software provides a selectable option that does software correction to ensure accurate results.
TexExpress Automotive Ethernet provides external reference clock input sources
Industry defined testing
In order to ensure hardware interoperability, the test software follows the test methods and test limits defined by the OPEN (One-Pair-Ethernet) Alliance Special Interest Group (SIG). The OPEN Alliance test suite documents are strictly followed to ensure that the instrument setups, algorithms and test outcomes are fully supported.
Test results can be defined to be a single measurement, multiple measurements or a test mask that is specific to a particular test. Examples shown are for transmitter PSD (power spectral density) and transmitter Output Droop.
PSD tests showing the compliance test comparing the results against mask limits.
Droop test compliance test results displayed in a table, along with limits and margin.
PSD testing source waveforms on 5 Series MSO.
Droop test showing source waveforms on 5 Series MSO.
Pass fail report
Creating compliance test documentation is quick and easy with a summary report in MHTML or PDF format. The report provides Pass/Fail status and is automatically generated after tests are completed. The report includes test configuration details, waveform plots, oscilloscope displays, and margin analysis, to provide more insights into your design.
Detailed test report showing SPD mask test plot
Probing and test fixtures
Accurate and repeatable compliance testing requires access to the PHY transmitter output and reference clock, and must support calibration and use of disturbing signals. The recommended approach is to use the Tektronix TF-GBE-BTP Ethernet fixture and the TF-BRR-CFD clock divider fixtures that can support all test setups while providing convenient test points for probing.
Tektronix TF-GBE-BTP Ethernet fixture
For direct probing of a DUT, use a differential probe with a bandwidth of ≥ 1 GHz. The Tektronix TDP1500 is the recommend differential probe.
- Required hardware
5 Series MSO oscilloscope (1 GHz option 5-BW-1000 or 2 GHz option 5-BW-2000)
Option 5-WIN or SUP5-WIN (removable SSD with Microsoft Windows 10 operating system)
- Required software
Option 5-CMAUTOEN or SUP5-CMAUTOEN (TekExpress Automotive Ethernet compliance)
Option 5-DJA or SUP5-DJA (adds Advanced Jitter and Eye Analysis measurements)
- Recommended options
Option 5-RL-125M or SUP5-RL-125M (adds 125 M record length)
Option 5-SRAUTO or SUP5-SRAUTO (adds CAN, CAN FD, LIN, FlexRay serial bus trigger and decode)
Option 5-SREMBD or SUP5-SREMBD (addsI2C, SPI serial bus trigger and decode)
- Recommended (two required): TDP1500 or TDP3500 differential probes
Supported: P6247 or P6248 (requires use of TPA-BNC adapter)
- Signal sources
Recommended: Tektronix AFG3252C signal source (recommended)
Supported: Tektronix AWG5000C or AWG7000C signal source (supported)
- Recommended test fixtures
TF-GBE-BTP Ethernet adapter
TF-BRR-CFD clock frequency divider
- Recommended extras
External PC monitor
Two pairs of 50 Ω high-quality SMA or coaxial cables (four cables total) for use with AFG or AWG signal sources; all cables must be the same length
Two 50 Ω high-quality coaxial cables for use with clock divider outputs; both cables must be the same length
One 50 Ω high-quality SMA cable for the clock divider input
One 50 Ω high-quality coaxial cable for the AFG or AWG signal source, for marker output