“New IEEE Automotive Ethernet standards are emerging, and one of the latest is 10BASE-T1S Ethernet. This article will discuss some of the megatrends in the automotive industry that are shaping the evolution of automotive electronics/electrical (E/E) architectures, and how the new 10BASE-T1S standard supports and enables new architectures.
New IEEE Automotive Ethernet standards are emerging, and one of the latest is 10BASE-T1S Ethernet. This article will discuss some of the megatrends in the automotive industry that are shaping the evolution of automotive electronics/electrical (E/E) architectures, and how the new 10BASE-T1S standard supports and enables new architectures.
The automotive industry is currently going through its most revolutionary period. Automakers need to quickly address several megatrends such as personalization, electrification, autonomous driving and full connectivity. OEMs will need to radically modify their Electronic/electrical architecture to support the new functionality. While this revolution presents significant technical challenges, it also presents an opportunity for OEMs to consider upgrading their electronic/electrical architecture from zone-based solutions, which are currently The platform becomes unwieldy as the number of components continues to increase. With this major architectural change, OEMs can focus on delivering superior technology solutions while adding new aftermarket revenue through features such as vehicle personalization, sales service and over-the-air upgrades (OTA). The industry is moving towards a general new architecture, commonly referred to as Zonal. And want to take advantage of technology and evolution in other industries, especially IT – because a car is essentially a computer on wheels.
Regional architectures determine connectivity by physical location rather than function, as is the case in domain-based architectures. This change significantly reduces the number of electronic control units (ECUs) in the vehicle and removes up to 1km of wiring harness wiring. Second, it decouples hardware and software, providing a service-oriented architecture (SOA). Many OEMs are investing heavily to bring software ownership in-house, aiming to provide an end-to-end solution that simplifies platform integration and provides more cross-functionality. This scalable software platform approach will minimize uncertainty and increase opportunities for new revenue streams, reduce R&D investment in the long run, and support multiple production lines on the same platform, thereby reducing development time.
These revolutionary architectural changes have created many challenges and have led many OEMs to restructure their entire organizations from a single group with ownership to a more integrated cross-functional organization that only provides domain-specific functionality.
Cars are fast becoming a major consumer of Ethernet equipment, and Ethernet, which is widely deployed in cars, is seen as one of the key technologies for the new architecture. Ethernet brings the required scalability, supports multiple speed grades, is a proven and robust transmission medium, supports service-based architectures, and has fully developed security blocks. Ethernet has a well-defined and easy-to-understand OSI model that makes it easier to manage the complexities of the entire automotive network.
Figure 1. Automotive area architecture. (Source: ADI)
The uniqueness of the car
While many basic Ethernet concepts can be leveraged from other industries, automotive electronics/electrical architectures have some unique requirements that dictate the need for new technology development. A focus of the car is to reduce the weight of the vehicle, which has a direct impact on the vehicle’s range. The cable harness currently used is one of the three heaviest subsystems in the vehicle (up to 60 kg). Traditional Ethernet cables use four differential signal pairs for data transmission, adding weight and wiring complexity that are not optimal for automotive applications. To solve this problem, new IEEE standards were developed to support Ethernet transmission over single twisted pair cable, which, combined with the reduced cable harness length specific to the zone architecture, can lead to significant cable and weight savings.
What is driving the demand for 10BASE-T1S?
As the concept of zone-based architectures evolves, it becomes clear that Ethernet connectivity all the way to edge sensors and actuators is required to take full advantage of this new architecture. Existing legacy connectivity technologies such as FlexRay and CAN require protocol conversion typically implemented in gateways, which adds cost, complexity and latency. Existing automotive Ethernet technologies such as 100BASE-T1 are not sufficient to support transitioning edge connections to Ethernet because the technology requires the use of point-to-point switched connections. The IEEE is therefore calling for a solution to this problem. Some key requirements include:
Faster communication than existing technologies; e.g. CAN(FD)
Replacing traditional in-vehicle networking technologies such as FlexRay
Alternative to 100BASE-T1 for ECUs as 100BASE-T1 is neither economical nor energy efficient
Ability to support simple and redundant sensor network connections
What is 10BASE-T1S?
The 10BASE-T1S specification was developed as part of the IEEE 802.3cg standard published in February 2020. 10BASE-T1S provides the missing link in the automotive Ethernet ecosystem, enabling a true Ethernet-to-edge connectivity architecture.
10BASE-T1S differs from other automotive Ethernet technologies in that it supports a multipoint topology, where all nodes are connected by the same unshielded twisted pair cable. This bus implementation provides an optimized BOM that requires only one Ethernet PHY per node, eliminating the need for switches or star topology implementations associated with other Ethernet technologies. The standard specifies that at least 8 nodes must be supported (more nodes can be supported), and the bus length must be supported up to 25 m.
Figure 2. 10BASE-T1S bus topology. (Source: ADI)
Another new feature of the standard is Physical Layer Conflict Avoidance (PLCA), which, as the name suggests, avoids conflicts on shared networks. The maximum latency will be mainly determined by the number of nodes on the network and the amount of data to be transmitted. Each node is assigned a transmission opportunity. If a node has no data to transmit at that time, it will hand over the transmission opportunity to the next node, thus achieving high utilization of 10 Mbps.
Since the 10BASE-T1S network is an AC coupled system, it is also possible to supply power through the 10BASE-T1S network. This will further save cables, reduce connector size and improve system reliability. Standardization of Power over Data Line (PoDL), which is already available for point-to-point implementation, is currently underway.
10BASE-T1S has a wide range and variety of applications in automotive, with many sensors and actuators under discussion covering various functions such as bodywork, comfort, infotainment and ADAS.
Automotive electronic/electrical architectures are undergoing revolutionary changes. The transition to a regional electronic/electrical architecture is imminent. 10BASE-T1S enables this transition with optimized Ethernet-to-edge connectivity. However, there are still some hurdles to overcome in this rollout, such as Ethernet connectivity that increases component cost and complexity of module implementation. 10BASE-T1S directly addresses these issues by reducing system cost and supporting multiple product options for different types of signal chain partitioning. ADI is promoting the introduction of 10BASE-T1S through active participation in standardization activities and close OEM cooperation to ensure that its system requirements are met.
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