Design Article
Ethernet tackles automotive EMI challenge
By Mike Jones, Micrel
1/2/2013 5:23 PM EST
Ethernet has already been widely accepted by the automotive industry
as the preferred interface for on-board-diagnostics (OBD) and has
been deployed in various car models since 2008. Ethernet provides
increased bandwidth speeds over traditional automotive buses,
resulting in a reduction in software download times from hours to
minutes compared to traditional methods. This adoption will be
accelerated with the introduction of a standardized IP Diagnostics
interface, as specified in ISO 13400, using Ethernet as the physical
layer.
The expansion of Ethernet-based networks in the automotive industry has continued with next-generation infotainment and driver assistance systems. Originally found in only luxury high-end vehicles, such applications are fast becoming differentiating features on mid-range and even basic models. These new applications have, in tandem, generated demand for greater system bandwidth, which continues to rapidly rise, as shown in the timeline below:
Advanced Driver Assistance Systems (ADAS) constitutes one of the fastest growing applications within the automotive market. Driven by government legislation and a desire for enhanced in-vehicle safety camera sensor networks are becoming commonplace. By 2017, camera-based module sales are expected to increase to 34 million in total, from 6.1 million in 2010 (IMS Research). This is in part due to the National Highway Traffic Safety Administration (NHTSA) ruling requiring every car sold in the United States from 2014 be fitted with at least a single rear view camera or sensor.
System costs are significantly lowered using Ethernet connectivity for multi-camera sensor networks in the car. Traditional proprietary methods are making way for open standard Ethernet. This has been reflected in the ISO 17215 Video Communication Interface for Cameras (VCIC) specification, defining Ethernet connectivity for use in vehicle camera and/or sensor applications.
Ethernet is emerging as the preferred network of choice for this new generation of networked vehicles, continuing to be the de facto networking bus for all other markets, thanks to an offering of ample bandwidth and open standardization. True standardization results in multiple interoperable supplier solutions, rapidly driving down costs.
This is in contrast to current popular infotainment networking technologies, for example MOST®. The proprietary nature of MOST® has often been blamed for failing to deliver the cost needs of car makers, as reported in the Hansen report, November 2008: “Suppliers and car makers think more access to SMSC’s proprietary MOST® technology would lower the cost of MOST® and increase market acceptance. Some are looking at Ethernet as a possible alternative.”
Ethernet provides many advantages over MOST® technology, including increased bandwidths and flexible topology, but probably most importantly lower costs, due to the high volume deployment across multiple markets, accepted supply chain and multiple suppliers.
Challenges for Automotive Ethernet
The needs of more recent Ethernet-based applications, such as infotainment and ADAS, differ distinctly from the current applications, such as on-board-diagnostics in that these are applications operating in real time and while the car is moving. No matter what the circumstances might be, must meet car manufacturers’ EMI limits. For Ethernet to be considered for any application in operation whilst the car is moving, it must fully comply with OEM EMI specifications.
Herein lies the challenge: the use of shielded cables would provide a solution to reducing radiated emissions within the car, but is usually undesirable. Shielded cable brings about complications in earth strategies, can adversely affect reliability, and add cost to production. Shielded cables cannot be manufactured in situ using wiring looms during production, but need to be pre-manufactured and purchased. Hence, the ultimate goal would be to operate Standard Ethernet over unshielded cable whilst meeting automotive OEM EMI limits. This solution dramatically reduces cabling costs, by up to 80%, over shielded counterparts, whilst maintaining interoperability with any other standard Ethernet device. The net result is lowest cost cable and silicon, with multiple suppliers.
The expansion of Ethernet-based networks in the automotive industry has continued with next-generation infotainment and driver assistance systems. Originally found in only luxury high-end vehicles, such applications are fast becoming differentiating features on mid-range and even basic models. These new applications have, in tandem, generated demand for greater system bandwidth, which continues to rapidly rise, as shown in the timeline below:
- 1981: CAN @1000 Kbps
- 2005: FlexRay @ 10 Mbps
- 2001: MOST @ 50 Mbps
- 2008: Ethernet @100 Mbps
- Ethernet @ 1000 Mbps (RTPGE IEEE802.3bp)
Advanced Driver Assistance Systems (ADAS) constitutes one of the fastest growing applications within the automotive market. Driven by government legislation and a desire for enhanced in-vehicle safety camera sensor networks are becoming commonplace. By 2017, camera-based module sales are expected to increase to 34 million in total, from 6.1 million in 2010 (IMS Research). This is in part due to the National Highway Traffic Safety Administration (NHTSA) ruling requiring every car sold in the United States from 2014 be fitted with at least a single rear view camera or sensor.
System costs are significantly lowered using Ethernet connectivity for multi-camera sensor networks in the car. Traditional proprietary methods are making way for open standard Ethernet. This has been reflected in the ISO 17215 Video Communication Interface for Cameras (VCIC) specification, defining Ethernet connectivity for use in vehicle camera and/or sensor applications.
Ethernet is emerging as the preferred network of choice for this new generation of networked vehicles, continuing to be the de facto networking bus for all other markets, thanks to an offering of ample bandwidth and open standardization. True standardization results in multiple interoperable supplier solutions, rapidly driving down costs.
This is in contrast to current popular infotainment networking technologies, for example MOST®. The proprietary nature of MOST® has often been blamed for failing to deliver the cost needs of car makers, as reported in the Hansen report, November 2008: “Suppliers and car makers think more access to SMSC’s proprietary MOST® technology would lower the cost of MOST® and increase market acceptance. Some are looking at Ethernet as a possible alternative.”
Ethernet provides many advantages over MOST® technology, including increased bandwidths and flexible topology, but probably most importantly lower costs, due to the high volume deployment across multiple markets, accepted supply chain and multiple suppliers.
Challenges for Automotive Ethernet
The needs of more recent Ethernet-based applications, such as infotainment and ADAS, differ distinctly from the current applications, such as on-board-diagnostics in that these are applications operating in real time and while the car is moving. No matter what the circumstances might be, must meet car manufacturers’ EMI limits. For Ethernet to be considered for any application in operation whilst the car is moving, it must fully comply with OEM EMI specifications.
Herein lies the challenge: the use of shielded cables would provide a solution to reducing radiated emissions within the car, but is usually undesirable. Shielded cable brings about complications in earth strategies, can adversely affect reliability, and add cost to production. Shielded cables cannot be manufactured in situ using wiring looms during production, but need to be pre-manufactured and purchased. Hence, the ultimate goal would be to operate Standard Ethernet over unshielded cable whilst meeting automotive OEM EMI limits. This solution dramatically reduces cabling costs, by up to 80%, over shielded counterparts, whilst maintaining interoperability with any other standard Ethernet device. The net result is lowest cost cable and silicon, with multiple suppliers.
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Snick
1/9/2013 6:22 PM EST
10 Jan. 08:22 Japan time
Your link to the second page here is broken.
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jpmcwil
1/16/2013 5:17 PM EST
I’ve been seeing more and more stuff about this lately. Just to put it out there- I think ethernet in the car is mostly a bad idea. The exception, where Ethernet in a vehicle might make sense, is as a communications interface to an on-vehicle diagnostic or programming gateway. This could help avoid needing a myriad of different service tools and special hardware interfaces to talk to various cars, or to the various systems on a single car.
Yes, Unshielded Twisted Pair is fairly cheap, but the added MIPS and software required to support Ethernet protocol isn't going to come for free in auto silicon anytime soon. And BTW, OPEN isn't the only thing that can run on UTP or even other lower cost wiring options.
Sure, everybody thinks Ethernet is great because of its ubiquity in home and business networks, but vehicles have very different requirements and needs than those applications. Sure, vehicles are getting a lot of technology, but they're still not a home office or media center, where a high level of interchangeability is required, and everything probably needs to talk to everything else.
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jpmcwil
1/16/2013 5:17 PM EST
What’s more, isn't the implementation of One-Pair-EtherNet (OPEN) basically a proprietary point-to-point physical layer, with a big 'ol bloated Ethernet protocol stack on top of it? There are a number of other efficient, vehicle–oriented P2P communication interfaces available, with HIGHER bandwidth, requiring much less overhead than is necessary to support “Ethernet.” I don’t think it will be practical to try connecting everything in a car together by “OPEN Ethernet” to the exclusion of such other reliable and inexpensive communications interfaces and proprietary protocols.
There’s a lot of marketing hype over “ethernet in vehicles,” I just hope the vehicle OEMs don’t get sucked into it. Although acceptance may line the pockets of the OPEN Ethernet SIG, it doesn’t buy anybody else anything not already available more cheaply and efficiently in other ways.
Sorry for the rant, at least in this article I didn't see anything about trying to use RJ-45 connectors, too. Where, in a vehicle, would an RJ-45 ever be suitable as a reliable, long term interconnect?!? lol.
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