Four major test analyses to improve vehicle ecology, safety and comfort

China's automobile production has surpassed the United States to become the world's largest, and will continue to grow in the next 5-10 years. The China Association of Automobile Manufacturers predicts that the growth rate of automobile production in 2010 will be around 10%, and is expected to reach 15 million vehicles. At present, many well-known companies have emerged in China, including automobile manufacturers, modular system suppliers and component suppliers, electronic equipment manufacturers, etc., especially FAW, Second FAW, BYD, Chery, Geely, Hangsheng, Changan and other local manufacturers have made great progress in independent development and innovation, which has driven the rapid development of China's automotive electronics industry.

However, in the face of increasingly complex automotive design requirements, especially when launching mid-to-high-end and commercial new energy vehicles, the road to independent innovation and development is not a smooth one. At a recent automotive electronics technology forum, experts from Tektronix Technology used the Toyota Lexus 460 car, which has "more than 100 ECUs and 7 million lines of software code", as an example to emphasize that electronic components account for an increasing proportion of automobiles, especially high-end cars. "As shown in Figure 1, automotive electronics are related to the three major market challenges of current automotive design, namely how to meet the requirements of ecology (environmental protection), greater comfort and convenience, and enhanced safety. The systems and subsystems that address these challenges are the hot spots and difficulties of current automotive electronics design." He pointed out. "The application of local area networks, power systems, electronic control units and digital RFID plays an important role in improving automotive ecology, safety and comfort.

Figure 1: Three major market challenges in automotive design have triggered more design hotspots.

Four major test analyses, none of which can be missing

Experts from Tektronix emphasized in their speeches that the use of local area networks (LANs) is increasing, whether for powertrains that need to improve fuel efficiency or adopt new energy, or for body and audio-visual entertainment systems that help improve driving and entertainment comfort, or for safe driving systems such as braking and steering, to achieve transmission control, body control or various wire control operations (X-by-wire control); due to the need to improve the energy efficiency of automobiles, the engine control unit and power supply system of automobiles have become more complex, and hybrid and clean fuel diesel engine technologies require advanced electronic control systems to ensure safety and environmental protection; using electronic control units (ECUs) to control basic and non-basic automotive systems is becoming a new industry standard. These ECUs are based on digital technology (MCU, FPGA and other devices), requiring a deeper understanding of complex timing and signal integrity issues; automotive safety systems use tire pressure monitoring (TPMS) and RFID systems, which require the development and measurement of real-time RF systems to be able to efficiently monitor vehicle operation and status.

1. LAN test analysis

Experts from Tektronix explained in their presentation that various serial data technologies and applications are being integrated into automotive designs to implement LANs, such as CAN, LIN, MOST, and FlexRay. Serial communications can improve circuit board design because serial interfaces are integrated into devices such as processors, ASICs, and FPGAs, reducing the number of connections and the total cost of components. The final automotive design usually contains multiple serial standards, mixed signals, mixed data rates, single-ended signals, and differential signals, which requires an integrated and easy-to-use high-quality test and analysis solution to complete timing between signals, signal integrity test analysis, and debugging.

For debugging low-speed serial buses such as CAN and LIN commonly used in automobiles, Tektronix's DPO/MSO4000 series oscilloscopes provide simple, easy-to-use, complete, high-quality trigger, capture and decoding solutions. As shown in Figure 2, this oscilloscope series provides search and mark functions, which can display the decoded CAN message frame with time stamp in the event table, a function that other competitive products do not have.

Figure 2: Tektronix’s DPO/MSO4000 Series oscilloscope CAN solution.

The DPO/MSO4000 series also provides debugging solutions for the emerging high-speed differential serial bus FlexRay. Tektronix's FlexRay physical layer analysis software DPO4AUTOMAX also fully supports physical layer analysis, providing a complete set of tools to evaluate physical layer performance, including eye diagram analysis, synchronization measurement, timing measurement, time interval error (TIE), and can be run with an external computer via USB or Ethernet.

(II) Power system test analysis

The power system is undoubtedly the heart of the car, and the high-quality and stable operation of the electronic circuits related to the power system will largely determine the performance of the entire vehicle, including both the electronic control part implemented by the ECU and the car power circuit, especially new energy vehicles.

The automotive ECU calculates information in real time based on the data sent back by sensors placed throughout the car to determine the optimal engine control parameter values. Since the ECU is built into the car engine compartment, the noise environment is even worse. At the same time, the demand for higher frequency analysis is also increasing, especially the anti-interference ability of microsecond, millisecond and even nanosecond transient signals or spikes, which poses a challenge to the analysis of nanosecond high-frequency noise by traditional oscilloscopes and probes. Tektronix experts recommend reducing the electrical load of the measurement system, including using differential probes with low input capacitance. Tektronix experts also provide signal source-based testing methods for some engineers who want to use signal sources for on-site simulation testing of power system electronic control units. For example, the AFG3000 series function signal generator is used to simulate various automotive sensor signals, such as pressure, temperature, speed, rotation and angular position, to perform functional testing and optimization of engine control units in automotive applications.

Figure 3: Measuring and optimizing an engine control unit using the AFG302xB and AFG3011.

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The test of automotive power circuit is similar to the power test on other electronic systems, and it needs to carry out major performance tests including switching loss, conduction loss, average power loss and safe operating area (SOA). At present, the industry already has complete, convenient and easy-to-use power test solutions. For example, Tektronix provides the most complete integrated power analysis solution in the industry, DPO4PWR and DPO3PWR power analysis application modules, which can realize comprehensive tests such as switching loss measurement, safe operating area, harmonics, ripple, modulation, conversion rate, etc., and can realize automatic measurement function, which can greatly simplify the power analysis work of automotive power application.

In view of the characteristics of completely floating ground testing in automotive electronics testing, Tektronix experts recommend that engineers use relatively expensive but higher-performance differential probes to ensure that the influence of the common mode part is eliminated during testing. "Sometimes we conduct single-board testing smoothly, but problems arise when running in the system. Many times, it may be caused by the failure to consider the influence of the common mode part during testing." He pointed out. He further shared with the engineers Tektronix's leading technology in probes: "For example, the TDP probe is particularly suitable for floating voltage measurement. Its input capacitance is less than 1pF, and it has the industry's unique probe programmable control feature, which is suitable for the implementation of automatic test systems."

3. Analysis of digital devices

In the electronic control units, infotainment systems and safety subsystems in automobiles, digital ICs such as MCUs and FPGAs are increasingly used to form various embedded systems. Tektronix experts pointed out that unlike CPUs that require logic analyzers for multiple channels, complex triggers, conditional storage, disassembly, and source code-level software debugging, a mixed signal oscilloscope (MSO) with excellent performance and full functional configuration is sufficient for debugging MCUs and FPGAs.

The following are two common timing measurements in embedded systems: events that are far apart in time - requiring the acquisition of multiple channels (long record length) with high timing resolution (high sampling rate) over a long period of time; digital state transitions - requiring the capture of signals in a short period of time, but with very high timing resolution. Real-time MSOs, such as the MSO4000 with the MagniVu application module, are particularly suitable for monitoring changes over time. In addition, the 16 digital channels of the MSO4000 can be set to different levels, allowing different logic types to be used in a design and triggering on setup/hold violations on multiple channels.

Regarding the debugging challenges of FPGAs, Tektronix experts listed the following points: 1. Design specifications and complexity are increasing, and access to internal signals is limited; 2. Time-to-market pressures are forcing product development and debugging cycles to become increasingly shorter; 3. Adding debugging circuits to FPGAs will affect design performance and take up valuable chip space, etc.

Figure 4: Cost-effective FPGA real-time logic debug solution.

Tektronix provides a cost-effective FPGA real-time logic debugging solution to meet these challenges: MSO4000 mixed signal oscilloscope or TLA series logic analyzer (>v4.3) + FS2 FPGAView control software, supporting FPGA manufacturer's multiplexer and JTAG cable, which can be easily completed in 4 steps: create an interface module à configure FPGAView for the debugging environment à map FPGA pins to MSO4000 or TLA series logic analyzer à take measurements.

In addition, Tektronix also provides the DPOxAudio audio analysis module, which can decode and analyze the I2S audio bus of the car entertainment system.

4. Digital RF testing

Some new safety and monitoring system technologies will widely apply RFID in automotive electronic systems, such as tire pressure monitoring (TPMS), anti-theft devices, keyless entry systems, and reversing radar components and systems. The application of RFID is increasing day by day, and some technologies used in high-end cars in the past will become standard equipment for most cars in the future. For example, the call for the establishment of mandatory standards for tire pressure monitoring systems is growing this year. Monitoring Tektronix experts also pointed out that in the application of reversing radar, domestic automobile manufacturers used to directly purchase modules for application, but now many have started to design them themselves, which will inevitably promote widespread application in more cars.

As mentioned above, in recent years, automotive electronic systems have become more and more complex, and more switching power supplies with strong EMI characteristics have entered automotive electronic systems. These have brought challenges to RF testing, and traditional spectrum analysis tools are used to test these transient signals. Tektronix experts have given some suggestions for automotive RF testing for engineers' reference: Tektronix's dual-channel signal generator AFG3022B can be used to generate 4-bit RFID code signals and synchronous trigger signals to achieve functional testing of 134.2kHz RFID receiver ICs; arbitrary waveforms and function generators can be used to generate complex signal environments in the car. For example, for reversing radar pulse noise figure measurements, the easy-to-use dual-channel AFG3252 can be used to generate two synchronous pulse signals to power the RF amplifier and trigger noise figure measurements on the spectrum analyzer.

summary

In recent years, China's automotive electronics design field has become increasingly active. Compared with the past when vehicle manufacturers mainly directly used mature foreign module products, many manufacturers have increased their efforts in independent research and development, and local automotive electronics design companies are also actively seeking cooperation with vehicle manufacturers.

However, data from market research companies show that the overall strength of automotive electronics design companies currently active in mainland China is still relatively weak, with only one local company in the top ten in the market ranking. As latecomers, local automotive electronics design companies must strengthen cooperation with leading technology providers to enhance product development capabilities. Currently, Tektronix has established extensive technical cooperation with leading international and domestic automotive electronics designers. As a leading provider of test and measurement technology, Tektronix's instruments will help engineers overcome the design challenges of automotive electronics and meet the market needs of ecology (environmental protection), greater comfort and convenience, and enhanced safety.