Ethernet and 1394 spar with MOST

  • 27-Jul-2009 11:52 EDT
Lexus uses MOST to carry infotainment data and graphs that show drivers details on fuel consumption.

Toyota recently deployed the Media Oriented System Transport (MOST) network as the infotainment network in its Lexus RX and Prius lines, highlighting a new battle in network design. Ethernet, 1394, and MOST are vying for a slice of the rapidly expanding infotainment market.­

M­OST is currently the dominant player in this nascent market, with usage in more than 65 car models, according to the MOST Cooperation. But it is facing increased competition from Ethernet and 1394, which are also being touted as architectures that provide benefits that the vehicle’s mainstream CAN (controller area network) architecture cannot provide.

Bandwidth is a primary factor. CAN is limited to 1 Mbit/s. MOST runs at up to 22 Mbit/s, while 1394 and Ethernet run at 800 Mbit/s and 1 Gbit/s, respectively. The two newcomers claim more speed is needed to handle a range of audio devices and other data.

The ability to handle video is equally important. Though video for rear-seat entertainment may be a limited market, many observers predict that navigation and cameras will increase the data flow in vehicles. Graphics such as those used by Lexus to show drivers how they are conserving fuel can also be carried on these infotainment buses.

The need for faster buses that deliver large video files without any interruptions is prompting many engineering staffs to adopt alternative networks instead of adding yet another CAN bus.

Over the past year, Ethernet has begun creating a buzz. It can easily be connected to home networks and other equipment. Its ubiquity means low pricing and ease of use.

“Everyone uses Ethernet, so there’s a lot of knowledge, and components are widespread,” said Mike Fawaz, Vice President of Engineering for Global Electronics at Lear.

Though its primary use could be in infotainment, that is not the first application to spark interest. Connecting to service-bay equipment may create the opening that leads to broader usage. “It’s coming in the back door, being implemented for diagnostics and debugging,” said Peter Schulmeyer, Microcontroller Strategy Director at Freescale Semiconductor.

To gain acceptance in infotainment, Ethernet will have to supplant MOST, which is now used by 16 carmakers, usually to carry video for rear-seat entertainment.

That acceptance is being expanded; the new Prius and the Lexus RX 350 and RX450h are the first Toyota vehicles sold worldwide to use the architecture. Hyundai also broadened its usage earlier this year, deploying MOST on its Equus.

“We’ve seen some of the bigger manufacturers on line to introduce MOST,” said Michael Bender, Network Bus Marketing Manager at Melexis.

MOST is also getting competition from 1394, which was also created to carry audio and video. 1394 supporters have made a number of upgrades in the past year, and the infrastructure of automotive grade products is expanding rapidly. They streamlined the architecture, also called FireWire, so far less software is needed.

“The ecosystem for 1394 automotive is in place,” said Max Bassler, Chairman of the 1394 Trade Association. “1394 has more bandwidth, more flexibility, and more supporters than MOST.”

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