Customers require features that can automate or enhance operational tasks to improve driver productivity, safety, and, in many cases, reduce total cost of ownership and operating costs. Currently, basic customer requirements for vehicles include automatic braking, adaptive steering, on-board diagnostics, vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication, and cameras providing drivers with a 360-degree all-around view.
These functions require the transmission of large amounts of data at high speed and low latency. As engineers design new models to meet these customer needs, the challenge lies in ensuring signal integrity and correct data transmission.
Design a hybrid architecture with Ethernet and CAN bus.
Controller Area Network (CAN) bus is a robust vehicle connectivity architecture that enables controllers and electronic devices to communicate with each other. The protocol supports features such as multiplexing to reduce the number of wires and cost in the system. It typically achieves speeds up to 500 Kbps and has been a reliable backbone connectivity architecture for most passenger and heavy-duty vehicles for decades.
However, the data bandwidth required for advanced vehicle functions and automated features for safety and productivity is too large to be served by CAN alone. A sophisticated network infrastructure is needed to handle the increased data demands and provide high-speed connectivity.
Upgrade to wired vehicle communication using automotive Ethernet.
Ethernet is the natural choice for automakers because the technology has stood the test of time. However, Ethernet on its own is insufficient; it lacks the robustness and responsiveness required for automotive applications.
Therefore, the industry has revised the Ethernet standard and developed special versions to suit specific applications. Automotive Ethernet, also developed with automotive applications in mind, differs significantly from home Ethernet. According to IEEE 802.3, automotive Ethernet is a subcategory of Ethernet, including single-balanced twisted-pair Ethernet protocols such as 100BASE-T1 or 1000BASE-T1, providing 100 Mbps point-to-point (P2P) full-duplex data transmission and 1 Gbps respectively.
Ethernet networks and connectors allow original equipment manufacturer (OEM) designers to seamlessly integrate more devices into the network and accelerate data connectivity in vehicles. As a peer-to-peer topology, Ethernet has transformed the electrical and electronic architecture of vehicles. As OEMs decide to add more features and devices, designers also need to consider Ethernet switches to guide signals and gateways to enable communication between Ethernet and CAN.
Optimize the selection and placement of communication links
To optimize space, weight, and performance under harsh conditions, designers must consider how to integrate Ethernet into where it is needed from the initial design stage.
This involves making decisions such as how many cables to place inside the vehicle, where to place them, where to place the Ethernet switch, and whether the switch should be in the existing electronic control unit (ECU) or whether a new dedicated ECU must be made for each function that requires Ethernet. These decisions are crucial for avoiding or mitigating electromagnetic interference (EMI) and other mechanical interference.
For example, a 360-degree camera on a heavy vehicle transmits high-speed data from outside the vehicle to an in-vehicle display so the driver is aware of their surroundings. Four cameras (one on each side of the vehicle) send signals to the ECU. System designers need to plan the placement of a switch to combine the data from the four cameras and send it to the ECU as a single signal. The switch could be located inside the vehicle, or it could be within one of the cameras, which has four ports for inputting data from the other three cameras and then sending the data. Another option is to integrate the switch into the video display monitor.
Building a future-oriented vehicle connectivity network
Active automation features (such as automatic braking and other ADAS systems that involve multi-sensor arrays) require more consideration in the early design stages. Each sensor has a dedicated communication link to the ECU. The more sensors a vehicle has, the more cables and connections are needed.
Future autonomous heavy-duty vehicles may require extensive sensor arrays, including approximately 16 radio detection and ranging (RADAR) sensors, 10 light detection and ranging (LIDAR) sensors, and 10 cameras around the vehicle. This involves more than 30 cables and links, requiring EMI-resistant and intelligent wiring while considering space, weight, and EMI to maintain signal integrity both inside and outside the chassis, as the links connect to an ECU.
Larger commercial vehicles bring more challenges
The sheer size of industrial and commercial vehicles presents challenges in maintaining signal integrity and reliable data transmission. The standard specifies a maximum distance of 15 meters for transmitting signals via Ethernet links in automobiles. However, for trucks, buses, and off-highway vehicles, signal integrity must be maintained over much longer distances, up to 40 meters or more, while withstanding severe vibrations, extreme temperatures, shocks, heavy dust conditions, and much more.
The Ethernet standard currently specifies a maximum of four cascaded connections within a 40-meter range. Designers need to evaluate how long each segment can maintain optimal signal integrity. Factors affecting this may include exposure to external components, high temperatures, placement near antennas, or other components that may cause EMI. Routing is a critical element of the design; the entire physical layer must scale as intended.
Choose the correct components
When designing a hybrid architecture with CAN and Ethernet, engineers need to consider the entire connectivity infrastructure in advance—that is, what advanced, high-volume data capabilities they will be integrating. The more advanced the technology, the more crucial collaboration becomes between original equipment manufacturers (OEMs) and suppliers.
In addition to a wide range of components, product experts and design engineers from brands such as TE Connectivity provide partners with product development solutions and consulting to ensure that designs are optimized to the maximum extent and that their lifespan is extended.
Abas Alwishah, Data Connectivity Engineering Manager at TE Connectivity, explains: “Let’s say a customer tells me they need a high-definition camera or proximity detection system with very low latency. In that case, I can explain all the individual components required to achieve that functionality or system. By sharing detailed information about the sensor, connectors, cable assemblies, antennas, processors, displays, etc., I can provide advice on topology to optimize performance, space, weight, and cost.”
Choosing Ethernet-compatible components capable of withstanding harsh conditions is crucial for reliable data transmission in long-life, heavy-duty vehicles. Automotive Ethernet connectors (originally designed for passenger cars) can be used in the passenger compartment or other vehicle areas unaffected by extreme shocks, temperatures, or other factors, where more robust connectors and longer cables are not required. High-quality unshielded twisted-pair cable is suitable for Ethernet in most areas of the vehicle, with shielded twisted-pair cable used only when necessary. The designer's choice will also help control costs and save space and weight.
For example, modular and scalable miniaturized automotive Ethernet (MATEnet) connectors for automotive Ethernet can be used in heavy-duty vehicles for applications requiring large to medium data volumes and low latency, such as on-board diagnostics, vehicle-to-everything (V2X) technology, telematics, dashboard infotainment, ADAS, etc. This connector can transmit data at speeds from 100 Mbps to 1 Gbps (according to IEEE 100BASE-T1/1000BASE-T1 standards) and can be used with unshielded or shielded twisted-pair cables.
Chassis-mounted components require more than just robustness. They must demonstrate mechanical reliability, maintainability, withstand extreme temperatures, and operate efficiently over longer channel lengths. When dealing with higher frequencies, the quality and design of cables/connectors significantly impact channel performance, ultimately affecting application performance. Especially for chassis-mounted components, engineers need to select cables and connectors specifically designed for high-speed data transmission in harsh environments.
Mark Brubaker, Data Connectivity Product Manager at TE Connectivity, believes that "when trying to meet mechanical resilience requirements, some engineers may instinctively consider adding a larger, more robust enclosure, but thicker walls can negatively impact electrical performance. It's important to understand what has worked historically, but also to further understand the electrical requirements of next-generation high-speed data transmission and test how the connection will perform at the higher frequencies involved."
in conclusion
When designing advanced and automated functions that require high-speed data transmission, product selection and placement cannot be an afterthought. When adding Ethernet to heavy-duty vehicle architectures, designers must consider and plan for the complexities involved earlier and more deeply than ever before. This is the only way to successfully balance reliability and mechanical resilience with the electrical requirements of high-speed data, longer channel lengths, and maintainability.
