In-vehicle systems have massively grown in complexity with more installed speakers, microphones, cameras, displays, and compute burden to process the necessary information and provide the proper, often time-sensitive output. The unfortunate side effect of this complexity is the massive increase in ECUs and subsequent cabling to and from its allocated subsystem like engine, powertrain, and braking.
The lack of practicality with this approach has become apparent with more OEMs shifting away from these domain-based architectures and subsequently traditional automotive buses such as local interconnect network (LIN), controlled area network (CAN) for ECU communications, FlexRay for x-by-wire systems, and media oriented systems transport (MOST) for audio and video systems.
SDVs rethink underlying vehicle architecture so that cars are broken into zones that will directly service the vehicle subsystems that surround it locally, cutting down wiring, latency, and weight. Another major benefit of this is over-the-air (OTA) updates using Wi-Fi or cellular to update cloud-connected cars; however, bringing Ethernet to the automotive edge comes with its complexities.
ADI’s approach to zonal architectures
This year at CES, EDN spoke with Yasmine King, VP of automotive cabin experience at Analog Devices Inc. (ADI). The company is closely working with the underlying connectivity solutions that allow vehicle manufacturers to shift from domain architectures to zonal with Ethernet-to-edge (E2B) bus, automotive audio bus (A2B), and gigabit multimedia serial link (GMSL) technology.
“Our focus this year is to show how we are adding intelligence at the edge and bringing the capabilities from bridging the analog of the real world into the digital world,” she said. “That’s the vision of where automotive wants to get to; they want to be able to create experiences for their customers, whether it’s the driving experience or whether it’s the back seat passenger experience.”
How do you help create these immersive and safe experiences that are personalized to each occupant in the vehicle? In order to do that, there has to be a fundamental change of what the architecture of the car looks like,” King added. “So, in order to do this in a way that is sustainable for mobility to remain green and preserve long battery life and good fuel efficiency, you have to find a way of transporting that data efficiently, and the E2B bus is one of those connectivity solutions where it allows body control, ambient lighting.”
E2B remote control protocol solution
Based on the OPEN alliance 10BASE-T1S physical layer (PHY), the E2B bus aims at removing the need for MCUs centralizing the software to the high performance compute (HPC) or central compute (Figure 1).
Figure 1: EDN associate editor, Aalyia Shaukat (left) and VP of automotive cabin experience, Yasmine King (right) are seen in front of a suspension control demo with 4 edge nodes sensing the location of the weighted ball. It sends the information back to the HPC to send commands to control the motors.
“The E2B bus is the only remote control protocol solution available on the market today for the 10BASE-T1S. We just released our first product in June 2024, and we see this as a very fundamental way to help the industry transform to zonal architecture,” King said. “We’re working with the OPEN alliance to be part of that remote control definition.”
These transceivers will integrate low complexity Ethernet (LCE) hardware for remote operation and, naturally, can be used on the same bus as any other 10BASE-T1S-compliant product.
BMW has already adopted the E2B bus for their ambient lighting system. King added that there has already been further adoption by other OEMs but they are not public yet. “The E2B bus is one of those connectivity solutions where it enables body control and ambient lighting. In fact, there’s about 50 or 60 different applications inside the vehicle.”
She mentioned how E2B is often used for ambient lighting today; but there are many other potential applications such as driver monitoring systems (DMSs) that might detect sleeping drivers via the in-vehicle biometric capabilities to then respond with a series of measures to wake them up. E2B allows OEMs to apply these measures with an OTA update.
Without E2B, you’d have to not only update the DMS, but you’d have to update the multiple nodes that are controlling the ambient light. The owner might have to take it back into the shop to apply the updates, which takes longer and is more of a hassle. “With E2B, it’s a single OTA update that is an easy, quick download to add safety features,” said King. So, it’s more realistic to get that safer, more immersive driver experience.”
The goal for ADI is to move the software from all edge nodes to the central location for updates.
A2B: Audio system based on 100BASE-T1
Based upon the 100BASE-T1 standard, the A2B audio follows a similar concept of connecting edge nodes with a specialization in sound. It limits the installation of weighty shielded analog cables going to and from the many speakers and microphones in vehicles, facilitating modern functions such as active noise cancellation (ANC) and road noise cancellation (RNC).
“We have RNC algorithms that are connected through A2B, and it’s a very low latency, highly deterministic bus,” King said. “It allows you to get the inputs from, say, the wheel base, where you’re listening for the noise and transport them to the brain of the central compute very quickly.” She mentioned how audio systems require extremely low latencies for an enhanced user experience, “your ears are very susceptible to any small latency or distortion.”
The technology has more maturity than the newer E2B bus and has therefore seen more adoption, “A2B is a technology that is utilized across most OEMs,” King added. ADI is working on a second iteration of the A2B bus that multiplies the data rate of the previous generation; this is likely due to the maturation of the 1000BASE-T1 standard for automotive applications that is meant to reach 1 Gbps. When asked about the data rate, she responded, “I’m not sure exactly what we are publicly stating yet, but it will be a multiplier.”
GMSL: Single-wire SerDes display solution
GMSL is the in-vehicle serializer/deserializer (SerDes) video solution that shaves off the significant wiring typically required with camera and subsequent sensor infrastructure (Figure 2). “As you’re moving toward autonomous driving and you want to replace a human with intelligence inside the vehicle, you need additional sensing capabilities along with radar, LiDAR, and cameras to be that perception sensing network,” King said.
Figure 2: GMSL demo aggregating feeds from six cameras into a deserializer board and going into a single MIPI port on the Jetson HPC-platform.
It’s all very high bandwidth and it needs a solution that can be transmitted in a low-cost, lightweight cable. Following a similar theme as the E2B and A2B audio buses, using a single cable to manage a cluster display or a human-to-machine interface (HMI) inside in-vehicle infotainment (IVI) minimizes the potential weight issues that could damage range/fuel efficiency.
King concluded by mentioning one overlooked benefit of lowering the weight of vehicle harnessing. “The other piece that often gets missed is that it’s very heavy during manufacturing, when you move over 100 pounds within the manufacturing facilities and you need different safety protocols,” she said. “This adds expense and safety concerns for the individuals who have to pick up the harness.”
Aalyia Shaukat, associate editor at EDN, has worked in the design publishing industry for six years. She holds a Bachelor’s degree in electrical engineering from Rochester Institute of Technology, and has published works in major EE journals as well as trade publications.
Related Content
- CES 2025: Moving toward software-defined vehicles
- CES 2025’s sensor design highlights
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