The main driving force for the rapid development of the automobile industry is gradually expanding from the focus on power systems in the past to the ever-increasing demand for intelligence. Smart cockpits and advanced driver assistance systems (ADAS) are intuitive experiences that consumers can perceive, and major brand car companies are also frantically “rolling in” on the road to actively show their muscles – for example, they have launched a configuration of 33 inches and a resolution of up to 9K LED super-large continuous screen, deployment of central control, co-pilot dual 15.7-inch 3K OLED dual-screen and large-size ceiling screen at the top of the rear row, 6 8-megapixel cameras and 5 2-megapixel cameras and 1 mmWave radar + 12 ultrasonic radars + 1 lidar and other sensing components…
Under the trend that cars have evolved from a simple means of transportation to a mobile travel space, the functions of the car are becoming more and more complex, and the exponential growth of data transmission and real-time processing has proposed high bandwidth, low latency and high reliability for the internal communication network of the car. new requirements have become one of the biggest challenges facing automakers. Among the killer trump cards offered by major semiconductor manufacturers in the industry, ADI’s GMSL (Gigabit Multimedia Serial Link) can aggregate data faster, maintain data integrity for security applications, support The system has the advantages of displaying different content on multiple screens of the vehicle, and has gradually stood out in the course of nearly 20 years of evolution. It has successfully deployed more than 500 million GMSL communication nodes in vehicles around the world, helping cars to achieve a more comfortable and intelligent driving experience and Safer autonomous driving goals.
The strong wind of automobile intelligent network connection, GMSL lays the “highway” for data transmission
Advanced assisted driving systems, high-definition audio and video entertainment, multi-sensor fusion, and intelligent body control have become more and more complex, and have gradually become the standard configuration of smart cars. The control information and audio and video data throughput between these configuration modules are as little as hundreds of Mbps , up to dozens of Gpbs, which is an unimaginable magnitude in traditional cars. Therefore, the realization of high-speed, high-reliability, and low-latency data transmission systems has become more important than ever.
Compared with the parallel bus, SerDes (Serializer/Deserializer, serializer/deserializer) is the current mainstream time division multiplexing, point-to-point serial communication technology, there is no interference between signal lines, and there is no same timing requirement. , higher data stream transmission can be performed only by increasing the frequency, which can effectively meet the real-time transmission requirements of high-bandwidth data in vehicles. According to research firm Kingpin Market Research, the global automotive SerDes market will increase from $194 million in 2020 to $349 million by 2026, with a compound annual growth rate of 10.3% from 2021 to 2026.
ADI GMSL technology is a kind of SerDes. The interoperability of serializer and deserializer chip allows the use of different interfaces on both sides of the link. It is widely used in high-speed transmission of UHD video, audio, control information, combined sensors and other data in the car. . The GMSL communication medium supports up to 15m of coaxial cable or 10m-15m of shielded twisted pair cable with considerable configuration flexibility and cost advantages, while meeting the most demanding EMC requirements of the automotive industry.
GMSL Serial/Deserialized Data Transmission Architecture Example Diagram
With the continuous evolution of automotive bus technology, ADI GMSL SerDes products have also continued to be upgraded iteratively. The MAX9247/9248, which came out in 2004, is the first generation of GMSL products, and can transmit up to 3 megapixels (1080p/30fps) video at a rate of 1Gbps. Streaming data; in 2017, the second generation of GMSL appeared, integrating complex diagnostic functions and increasing the bandwidth to 6Gbps, which can easily transmit 8-megapixel (4K/30fps) video streaming data; now the third generation of GMSL and The transmission rate of the fourth-generation product can reach 12Gbps, which further highlights the competitive advantage over other solutions in the industry in terms of high bandwidth, complex module interconnection and data integrity assurance required by future automotive infotainment and advanced driver assistance systems.
ADI’s R&D History on GMSL Differential Signal Transmission Products
- The evolution of multi-screen smart cockpit is “more than big”
Gordon Wagner, chief design officer of Daimler, the parent company of Mercedes-Benz, once pointed out that “the screen is the window to the digital world, and the screen is the new horsepower”. In addition to the center console, the instrument panel of the driving controls and the rear-seat entertainment display are constantly increasing in size and resolution in the current car cockpit. Not only that, but automakers are actively trying to add mirror displays to project images from rear cameras, among other things. The future high-definition multi-screen interconnection will not only be larger in size and clearer in picture quality, but also more flexibly and effectively interconnect with the intelligent vehicle system, which will greatly improve the user’s driving experience and open up a perfect “third living space”.
The central control display is getting bigger and more high-definition, and the bandwidth demand for video data information transmission is getting higher and higher.
From the perspective of the implementation architecture, the number and resolution of in-vehicle displays have increased, and the complexity of interconnection with the vehicle SoC system is increasing day by day. The control of multiple screen display and interaction is realized in the same set of hardware platform. Based on the GMSL SerDes technology, the video source data can be returned from the processor unit to each vehicle display screen, and different contents can be displayed on multiple screens. As a two-way transmission connection, GMSL can also transmit and integrate control signals, such as touch detection and information processing of the display screen. Since one GMSL serializer can drive up to four deserializers, it is theoretically possible to transmit data information of four screens at the same time.
In terms of supporting the improvement of in-vehicle display pixels, the current mainstream GMSL third-generation products have been able to achieve 8-megapixel 4K resolution video data transmission, thanks to GMSL’s support for VESA and MIPI display streaming compression technology (DSC). ), this technology is aimed at the high-quality audio and video transmission requirements of high-end electronic equipment, and can achieve 3:1 lossless compression of video signal transmission. In addition, the digital interface compatible with different types of car screens is another challenge in the design of high-speed communication links. GMSL not only supports the mainstream DP/eDP, DSI and other interfaces of the display, but also supports most high-definition camera video data transmission applications. MIPI CSI-2 interface. It is worth mentioning that each generation of GMSL products is compatible with the PCB design on the chip pins, making the new generation of SerDes chips forward compatible and matching, helping customers to seamlessly upgrade and replace SerDes products, reducing overall costs and simplifying the cockpit system. The layout design of the data transmission link.
- High-speed transmission of ADAS images needs to pay equal attention to data security
The technology of intelligent and connected vehicles has entered a critical period of implementation, which is reflected in the fact that more and more new cars use high-resolution cameras to meet the high standards of environmental perception in the era of intelligent driving. With the gradual upgrade and accelerated penetration of ADAS, and the high hardware redundancy of various car companies, it is expected that the average number of high-definition cameras installed in a single vehicle is expected to be close to 10 by 2025. At the same time, the penetration rate of the 8-megapixel camera has gradually increased, allowing the car to “see” more clearly, farther and wider, meeting the needs of more application scenarios.
Since the camera is usually only responsible for collecting and outputting the original video signal, in addition to the “eyes” with higher pixels, the “optical nerve” and the “brain” of the central processing unit with high computing power are also required for lossless and delay-free transmission. The transmission of video signals with higher frame rates and resolutions puts more pressure on the bus bandwidth. The ADAS system receives the signals in real time and analyzes them to respond. It is also necessary to consider the cost and power consumption of the entire system.
GMSL fully supports the high-speed data transmission and signal integrity assurance required by ADAS systems, including ultra-low-power operation of cameras and rapid aggregation of sensor data. Since GMSL technology has the video cutting function, taking the GMSL four-channel deserializer MAX9286 as an example, it can automatically generate camera synchronization signals, align the image data of multiple sensors to the same pixel, and realize user programming of key parameters. Instead of four discrete deserializers and one FPGA, only a single chip can receive and synchronize video signals from four cameras, greatly reducing board area and component count, effectively reducing design risks and speeding up the time-to-market process.
GMSL four-channel deserializer MAX9286 can support the signal transmission of four cameras at the same time
Not only that, the GMSL deserializer integrates the image processing function. After receiving the GMSL serialized data, it can directly perform deserialization and image processing, and perform splicing and restoration of multi-channel image information according to customer requirements, and present it on the vehicle display. On the screen, the delay of image processing by the central processing unit platform is saved. GMSL also supports Power over Coax (POC), so the serializer chip can be integrated into the camera, and the camera can be powered directly by the on-board system.
It is worth mentioning that all GMSL solutions meet the requirements of the automotive functional safety standard ASIL B specification. Since both the GMSL serializer and deserializer have built-in spread spectrum functions, the electromagnetic compatibility of the link is effectively improved without the need for an external spread spectrum clock. This is also the biggest advantage of GMSL product solutions, which can effectively help customers’ system design meet Vehicle-level standard. In addition, the GMSL solution also provides a link diagnostic function, which monitors the transmission quality and data integrity of the channel in real time, and enhances driving safety by improving the reliability of automotive ADAS data.
Data integrity is one of the three key challenges for ADAS and infotainment systems
Shaping the future of connected and personalized cars with innovative data bus connectivity
Entering the era of digital economy, data has become a new means of production and a key factor of production, and high-bandwidth data transmission is becoming a rigid demand for the next-generation vehicle electronic architecture. In fact, ADI has done a lot of exploration and fruitful industrial technology output on high-reliability vehicle data bus transmission.
Also in the smart cockpit, car audio has developed from a simple entertainment system in the past to signal input, triggering, processing and feedback, and has begun to be closely integrated with car driving. ADI’s innovative A2B audio bus technology transforms traditional analog audio transmission into a digital audio transmission solution that delivers high-fidelity audio while reducing audio wiring weight by 75 percent, improving fuel efficiency. In addition to making wiring simpler, A2B has more innovative applications, such as being more adaptable to advanced audio algorithms, using DSP algorithms to ensure the independence of sound zones in different positions in the car, and implementing echo cancellation, ANC active with microphones and power amplifiers Noise reduction and other functions.
A2B technology provides low-latency voice and audio connectivity
Automobiles are also rapidly becoming one of the main applications using Ethernet devices. Widespread deployment of Ethernet in automobiles is one of the keys to the transition of the vehicle’s electrical and electronic architecture to a region-oriented approach, which can significantly save cable costs and significantly reduce the number of ECUs. And support for deploying new features and enhancements via over-the-air updates. ADI’s E2B Ethernet-to-Edge bus based on the new IEEE 10base T1S standard provides efficient, deterministic last-mile connectivity for many in-vehicle sensors and actuators, making it easier to manage complex networks throughout the vehicle.
Today, the biggest changes in the automotive industry are happening at the same time. One is electrification, and the other is intelligence and networking. As the world’s leading supplier of automotive semiconductor solutions, ADI has been working closely with excellent automotive OEMs, Tier 1 suppliers and ecosystem partners to expand core technologies and strengthen complete solutions at the system and platform dimensions to provide advantages. The ADI series of automotive connectivity solutions represented by GMSL SerDes technology will help address a series of challenges such as complexity, weight and cost of automotive data transmission link design, bringing great value to automakers and jointly shaping interconnection and personalization The future of the car.
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