What benefits will Automotive Ethernet deliver to vehicle cable harnesses?
The typical cable harness in an average automobile is the third heaviest item as well as being the third most expensive to manufacture. Only the chassis and engine, for internal combustion engine-based vehicles, weigh and cost more. With vehicles moving to hybrid and all-electric drivetrains, weight reduction remains high on the list of required improvements. However, this cannot be achieved with innovation in conductor material weight alone: it requires a fundamental change in the E/E architecture to reduce the number of networking topologies in use.
With the advent of automated driver-assistance systems (ADAS), and autonomous driving on the horizon, it is also clear that existing in-vehicle networking solutions provide neither the bandwidth, nor the flexibility, to handle the masses of data generated by cameras, radar, LiDAR and other sensors.
Ethernet has been in consideration as an option for a long time. It provides a suitable topology for automotive applications and more than enough bandwidth. Unfortunately, a lack of support for guaranteeing latency or performing traffic shaping, along with electromagnetic-compatibility challenges, meant that the existing Ethernet technology could not be imported into the vehicle without some significant modifications.
By focusing on the strengths and developing strategies to overcome the weaknesses, standards organizations have developed a range of new standards which are commonly described as Automotive Ethernet. These make changes to the lower three layers of the OSI model, starting at the physical layer. Rather than a shielded CAT5e cable, data can pass over a single full-duplex twisted-pair connection. To ensure that latency for audio and video data is kept to a minimum, bandwidth can be reserved between two points in the network. Further options are also provided for highly time-sensitive applications where Automotive Ethernet is part of a control loop.
Other optimizations include synchronization with a master clock, allowing audio and video packets to be synchronously presented or sampled at differing nodes. This allows audio systems to both output audio and sample vehicle noise from two or more Automotive Ethernet nodes at the same moment in time.
Applications for Automotive Ethernet will range from highly complex domain controllers featuring a powerful system-on-chip (SoC), down to simpler electronic control units (ECU) that only really demand a 32-bit microcontroller. To meet these needs, the TC9562 from Toshiba is designed to operate both as a PCIe peripheral, as well as a standalone Automotive Ethernet node using its integrated 32-bit processor. In combination with an SoC its direct memory access (DMA) feature can automatically forward data packets from selected IP addresses to separate areas of the host’s DRAM memory. Standalone it can be coupled with an audio CODEC and amplifier to both output audio and capture input from a microphone for a noise-cancellation or hands-free application.
To find out more about the technology behind Automotive Ethernet and how the TC9562 can be used to utilize these new features, take a look at our white paper available here:
