Controller Area Network (CAN) networks are likely to be around for many years, but at the high end of the automotive market they are already beginning to lose some ground to FlexRay.

FlexRay is 10 times faster than CAN (10 Mbps versus 1 Mbps); it's time-triggered and deterministic, which makes it predictable, where CAN is not, and because it's predictable, some say it makes application development easier.

FlexRay is a dual-channel protocol that supports redundancy. It's fault-tolerant, and generally considered to be more reliable than CAN. It also works harmoniously with CAN, Local Interconnect Network (LIN), and Media Oriented System Transport (MOST) networks, and the FlexRay Consortium is pursuing alignment of the FlexRay protocol with two other automotive industry standards, AUTOSAR and JasPar.

“The market drivers behind FlexRay include the need to improve fuel economy and reduce CO₂ and other harmful emissions, safety, and making cars fun to drive,” said Bjoern Steurich, senior manager for automotive microcontrollers at Infineon Technologies North America. “Vehicles today have as many as 80 ECUs (electronic control units), and networks based on current technology have become overly complex and error-prone. The industry needs a strongly deterministic and fault-tolerant system bus.”

BMW launched the FlexRay era a little more than a year ago with a ride-smoothing application called AdaptiveDrive. The automaker is in the process of implementing FlexRay on several additional models, but the protocol has maintained a low public profile.

Meanwhile, FlexRay is the focus of significant development efforts in labs around the world. “We're experiencing the silence before the storm,” said Rob Hoeben, marketing manager for FlexRay in NXP Semiconductors' automotive business unit. “FlexRay adoption began with German OEMs, but OEMs in Detroit and in Japan are following suit.”

NXP announced in March that its TJA1080A node and star transceiver (Figure 1) passed the FlexRay Physical Layer Conformance Test, the industry standard for FlexRay products. Hoeben said that compliance to the test is an important step in the proliferation of the FlexRay standard because for OEMs it translates into faster development times and fewer production issues. The device, due to ship in the second quarter, provides an interface between the protocol controller and the physical bus in a FlexRay network, monitors internal voltage and temperature, and supports the mode control used in NXP's TJA1055 and TJA1041 CAN transceivers.

Hoeben said BMW is using the TJA1080A predecessor, TJA1080. Among the enhancements in the newer version is full conformance with FlexRay Electrical-Physical Layer V2.1 for improved EMI/EMC performance, improved power-on reset behavior, an upgraded transmitter circuit to reduce emission on bus lines, and an enhanced receiver circuit for higher RF immunity, up to 70 ns minimum bit time.

“We're seeing a trend toward ECUs functioning as central gateways in ABS or suspension applications, with an active star device connecting the MCU by its branches to an ECU containing a node transceiver,” Hoeben noted. “In the future we expect to see more central gateways connected by four or eight branches to more ECUs.”

While the TJA1080A contains a node and an active star in the same device, Hoeben said next-generation devices are likely to contain a node or an active star, in order to give designers more flexibility by enabling more topologies and optimize system deployment costs.

Application developers are benefiting from a growing number of network-specific chips and design tools as they prepare new networks for launch.

NEC Electronics America targets chassis applications, among others, with the 32-bit V850E/PHO3 MCU, which features an embedded FlexRay controller based on E-Ray intellectual property licensed from Robert Bosch GmbH.

Built on NEC Electronics' V850E CPU core, which operates at clock speeds up to 128 MHz and features 1 MB of embedded flash memory, the V850E/PHO3 MCU was one of the first MCUs to pass the FlexRay Conformance Test administered by TÜV Nord Group's Institute for Vehicle Technology and Mobility, the FlexRay Consortium's partner for data link layer conformance testing. The certification is based on 275 tests that verify the functional behavior of an embedded FlexRay communications controller to ensure conformance with the FlexRay v2.1 specification.

“CAN and LIN are well accepted, but there is not much going on with them,” commented Jens Eltze, new business development manager in the Automotive Strategic Business Unit at NEC Electronics America. “FlexRay is the networking technology in the spotlight. It's having big success in Europe, and initial success in Japan and the U.S.”

Eltze said FlexRay holds appeal for developers of steering systems. The V850E/PHO3 has the ability to control one or two 3-phase brushless DC motors simultaneously for applications including electronic power steering, as well as electronic braking, damping and other vehicle-stability control applications.