Ethernet succeeds in automotive environments
The latest version of the automotive infotainment bus system, MOST 150, has yet to enter the serial production phase, but now Ethernet seems to emerge as a powerful rival. At the VDI congress on automotive electronics in Baden-Baden (Germany), several players launched commitments to Ethernet as a future standard for in-car data communications.
"After years of relative standstill, the field of automotive EE architecture has started to move again", said Helmut Matschi who oversees the Division Interior of automotive supplier Continental AG. "With Ethernet, we anticipate a lot of changes in intra-automotive networking".
During a press roundtable, Matschi explained that the tier one company sees enormous advantages for Ethernet in automotive environments. The networking standard from commercial IT could help to drive down costs without compromising performance or safety. Currently, for high-bandwidth data transmission, automakers have two alternatives: LVDS (Low Voltage Differential Signaling) and MOST. LVDS is fast, but expensive since it requires shielded cables. MOST is also rather fast and its EMC characteristics are undisputedly excellent, but its optical wiring is very expensive and difficult to handle in the car production ("A nightmare", said an engineer familiar to the matter). Ethernet hitherto had a problem: It’s EMC characteristics was not as good as it should be as long as cheap UTP cable was used, and shielded twisted pair was not cost effective.
The Ethernet Physical Layer for automotive environments developed by Broadcom is the key element for a breakthrough of Ethernet in this environment. It enables OEMs and suppliers to implement Ethernet-based data bus systems without EMC problems and at very low cost in even safety-critical automotive environments, Matschi said. He added that in collaboration with Broadcom Continental has developed its own circuits to defuse the EMC problem on Ethernet UTP cables.
Matschi said the roll-out of Ethernet in cars can also be regarded as an element of the merger between the outside IT world and the hitherto isolated in-car electronics landscape. But advanced driver assistant systems with very high data rates and the increasing usage of data from the outside world such as car-to-x communications systems and cloud-based services would make a closer integration a logical step.
At the semiconductor level, chip vendor Freescale demoed at the congress a camera-based parking assist system utilizing Ethernet – instead of the competing MOST bus – for the connection between camera and ECU. The chip vendor used the physical layer that was adapted to automotive requirements by Broadcom.
The very same application was in detail presented by carmaker BMW as part of its commitment to Ethernet. BMW was the first carmaker to use the de-facto data communication standard in automotive environments: Already in 2008, BMW utilized Ethernet to connect the OBD-interface (on-board diagnostics) with the car’s head unit. The rationale at that point of time was that with Ethernet it was possible to significantly speed up the process of downloading the application software into the car ("flashing") at the end point of the production line. This Ethernet version however was not fit for "live" automotive use – it could not be activated during driving due to EMC issues.
BMW now unveiled that it entered a close collaboration with Broadcom for the development of a PHY layer that avoids these problems. "So far it was not possible to use Ethernet despite its merits such as low cost and high performance in automotive environments", explained BMW engineer Albrecht Neff in his presentation. The camera-based assistant system with 360 degree view angle demoed by Freescale actually is a pilot project by BMW. Neff described Ethernet as an "elegant solution for cost-efficient, scalable automotive networking".
Continental’s Matschi said his company is "fully committed" to deploy Ethernet in cars. Until 2020 – automotive design cycles are still somewhat slower than commercial IT design cycles – Continental plans to establish Ethernet in all automotive domains including chassis and safety. "Even an entire car based on Ethernet would be imaginable", Matschi said. "We are at the point where the skeptical stance among the carmakers is vanishing".
And MOST? MOST however will not disappear, Matschi said – at least not immediately. "We continue to support MOST. But under the bottom line, it is the carmaker’s decision."
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