FlexRay goes Live

The first FlexRay application to enter production was an option called AdaptiveDrive on BMW's X5 sport activity vehicle (SAV). Based on 32-bit FlexRay microcontrollers from Freescale Semiconductor, AdaptiveDrive monitors data on the speed of the vehicle, its steering angle, longitudinal and lateral acceleration, body and wheel acceleration, and ride height.

When the driver presses a button to select either a “sporting” or a “comfort” ride, AdaptDrive appropriately adjusts the vehicle's side angle and damping by controlling the swivel motors in the anti-roll bars and the electromagnetic valves on the dampers (Figure 1). The control units interact to prevent imminent body roll, and BMW engineers selected FlexRay, with its 10 Mbps bandwidth, to gain fast data transfer between them.

“This (2007) will be the year when major automakers worldwide will accelerate the rate of FlexRay design-ins into their high-end vehicles,” said Toni Versluijs, business development manager at NXP Semiconductors.

“BMW is implementing FlexRay in several models, beginning this year. The next car models featuring FlexRay will hit the market in 2008, 2009 and 2010 with an ever-increasing role for the bus over the next decade,” he said. “FlexRay will start in high-end vehicles, where it will replace CAN modules. In lower-priced vehicles, increased node count will be fully supported by CAN and LIN until FlexRay is proliferated through all vehicle classes. This will occur over the next decade.”

Earlier this year, the FlexRay Consortium released FlexRay V2.1 protocol and physical layer conformance tests, thus completing the FlexRay V2.1 specification set. Semiconductor suppliers can submit communication controllers and physical layer devices to the conformance test partners, which include TÜV Nord for protocol conformance and C&S Group and TZ Mikroelektronik for physical layer conformance. Products must pass the conformance tests to be certified as compliant to the FlexRay V2.1 standard.

“Now, automotive manufacturers can benefit from a common standard across regions and across their own vehicle platforms, which simplifies design, production and ultimately reduces costs,” said Claas Bracklo, FlexRay Consortium spokesperson and head of hardware and software components at BMW.

“With the conformance tests in place, carmakers around the world can begin using the FlexRay standard in their new vehicle platforms.” Bracklo said market adoption of FlexRay “is expected to accelerate very quickly” now that FlexRay is in production. “Several members of the consortium have definitive timelines and plans for using FlexRay in their vehicle platforms,” he said.

Also encouraging the use of FlexRay is semiconductor technology developed by NXP and Freescale under a partnership agreement and made available for license through IP-Extreme.

NXP offers a FlexRay system consisting of an 80 MHz SJA2510 FlexRay 2.1 controller and a TJA1080 transceiver. The controller is based on a 32-bit ARM968 CPU with up to 1 MB of embedded flash memory and more than 48 kbytes of SRAM. It has 32 analog inputs, and 24 16-bit pulse width modulation (PWM) outputs, and can support six controller area network (CAN) 2.0B controllers and eight local interconnect network (LIN) 2.0 master controllers. The TJA1080 operates in node and active star mode and serves as a building block in numerous FlexRay topologies.

Freescale's FlexRay offerings include the MC9S12XFR and MFR4300. The MC9S12XFR is based on a 16-bit, 40 MHz HCS12X central processor with an XGATE co-processor. It also includes a FlexRay 2.1 protocol module for serial communication up to 10 Mbps on each of two channels, 128 KB of flash memory with optional error code correction (ECC), 2 KB of electrically erasable programmable read-only memory (EEPROM), 16 KB of random access memory (RAM), and either a 0.5 MHz to 16 MHz or 0.5 MHz to 40 MHz crystal oscillator. The MC9S12XFR also includes a 16-channel analog-to-digital converter, six-channel PWM, and support for CAN 2.0 A/B.

The MFR4300 features selectable FlexRay 2.1 single- or dual-channel support; 128 message buffers configurable with up to 254 bytes of data, and two configurable receive first-in first-out (FIFO) message buffers.

NXP and IPextreme Inc. are jointly marketing a FlexRay verification environment for validating system-on-chip (SoC) designs in FlexRay networks (Figure 2). Using the Cadence Incisive verification platform from Cadence Design Systems, Yogitech SPA helped NXP create an e-verification component (eVC) for use by FlexRay customers. Subsequently, the eVC validated the FlexRay executable reference model that serves as the basis for the FlexRay conformance test.

The verification component expands NXP's FlexRay portfolio from products to IP. “The application of IPextreme's IP integration and licensing expertise to our FlexRay verification component will help drive forward the adoption of highly reliable FlexRay networks,” said Paul van der Plas, general manager of NXP's automotive business line.

“Bundling this verification solution with the FlexRay controller core that we sell and support from Freescale creates a complete solution for anyone who wants to add a FlexRay interface to their chips,” said IPextreme chief executive officer Warren Savage.

Noting that the FlexRay standard defines many options that yield thousands of possible communication configurations, Savage said the eVC kit enables engineers to do constrained random verification on defined configuration ranges to ensure correct behavior of their implementations.

Savage explained that FlexRay controllers typically consist of two main blocks, a control host interface (CHI) and the protocol engine (PE). The CHI gives the host processor access to FlexRay setup, control, monitoring and transmit/receive services and the PE handles FlexRay traffic and protocol functionality.

He said the CHI is usually customized to allow for end product differentiation, while the PE remains consistent to ensure FlexRay compliance. IPextreme's FRCC2100 intellectual property (IP) includes the PE and a pre-verified CHI interface that supports the use of individual receive and transmit buffers, with single and double-buffered transmit; state or event transmission modes; receive FIFO functionality; message buffer filtering; frame monitoring, and a dual-channel mode.

“The FRCC2100 is cleanly partitioned such that customers can add their own CHI to the proven PE,” Savage said, adding that the FlexRay eVC kit can verify the custom CHI as well as the entire FlexRay system.

Dependable Computer Systems GmbH (DECOMSYS) last fall acquired a license from IPextreme to use the FRCC2100 IP, which is implemented in Freescale's MC9S12XFR128, MFR4300 and MPC55xx power architecture controllers, in BMW's AdaptDrive, and in NXP's SJA2510 ARM9 controller. DECOMSYS plans to use the IP in its hardware and in its monitoring solutions such as DECOMSYS:: BUSDOCTOR 2 (Figure 3), replacing the MFR4200 it had been using.

Other semiconductor companies are entering the FlexRay market. Fujitsu Microelectronics America markets the MB88121, an application-specific standard product (ASSP) based on the E-Ray core licensed from Robert Bosch GmbH. The MB88121 supports two-channel operation and features more than 8 KB of message buffer memory for support of up to 128 different identifiers.

In March, Fujitsu introduced a FlexRay controller for driver-assistance applications. Built on a 32-bit, 100 MHz Fujitsu FR 70 CPU with a 3.0 V to 5.5 V voltage range, the MB91F465XA uses the Bosch E-Ray core and VHDL code certified by TÜV Nord. It supports two-channel and FIFO operations, as well as 218 different identifiers, by providing more than 8 KB of message buffer memory.

In addition to its two-channel FlexRay bus interface, the Fujitsu MCU includes one I2C, two CAN and three LIN-USART interfaces. Other features include 544 KB of flash memory with read-out protection; 32 KB of RAM; a hardware watchdog; a 17-channel, 10-bit analog to digital converter; reload timer; stopwatch function, and an RTC module that can operate on external 4 MHz or 32 kHz quartz crystals (Figure 4).

Infineon Technologies is developing a bus system consisting of a stand-alone FlexRay protocol controller that can be integrated with 16-bit and 32-bit microcontrollers; also a transceiver, software and peripherals. Infineon plans to use FlexRay IP developed by austriamicrosystems AG. Paul Fox, director of marketing for Renesas Technology America's Automotive Business Unit, said his company is developing 32-bit CISC and RISC microcontrollers that will support FlexRay.

Meanwhile, Infineon, Renesas and other companies offer a range of products for CAN and LIN networks. Renesas' portfolio includes a LIN hardware control circuit that reduces the number of interrupts required for synchronization, and offers bus collision detection and a wake-up function. The LIN controller can be run with 5% accuracy using the internal oscillator or can be trimmed via software to 1% accuracy. The internal oscillator eliminates the need for an external clock and frees two I/O pins.

Texas Instruments' TPIC1021 stand-alone LIN 2.0 transceiver eliminates the need for external protection components by providing up to 17 kV IEC and 12 kV human body model (HBM) electrostatic discharge (ESD) protection. The SN65HVD1050Q, an automotive-qualified (AEC-Q100) CAN transceiver, features up to ±8 kV HBM ESD, sufficient to reduce the need for external protection components.

NEC Electronics America's V850E/Dx3 family of 32-bit automotive-grade microcontrollers features two CAN interfaces in addition to on-chip stepper motor drivers, LCD controllers/drivers, parallel LCD bus interfaces and sound generators.

Development tools vendors are updating their products to capitalize on the advent of FlexRay. Elektrobit recently added FlexRay as an integrated component of its tresos automotive standard core, which already included CAN and LIN. The company said it will be possible to undertake the basic configurations of a FlexRay stack within tresos electronic control unit (ECU) tooling. Operating system (OS), run-time environment (RTE) and FlexRay module configurations are consistent within tresos and engineers developing time-synchronized applications will be able to describe intermodular dependencies with simple XML expressions. A tuned tool chain that includes tresos and DECOMSYS' FlexRay DESIGNER ASR will allow engineers to import and expand AUTOSAR configurations.

DECOMSYS teamed with Agilent Technologies on an oscilloscope for FlexRay triggering and protocol decode measurement. It combines an Agilent 6000 series mixed-signal oscilloscope (MSO) with a DECOMSYS::BUSDOCTOR 2 protocol analyzer to provide time-correlated slot/segment boundary display of the global FlexRay timing schedule, including the ability to trigger on specific FlexRay communications qualified on base-cycle and cycle-repetition. Designers can see a synchronous and time-correlated display of segment and slot timing boundaries by importing a FIBEX file that defines the global FlexRay schedule into the Agilent MSO.

TTAutomotive has released TTXBuild — software for developing and optimizing FlexRay-based electronic control units, designing nodes, and configuring automotive systems based on AUTOSAR specifications for the FlexRay stack. The tool is said to be capable of automatically configuring the complete software stack in a single step. For process integration, it provides batch mode execution and node configuration via scripting. It checks for consistency with the FIBEX communication database and ensures valid AUTOSAR configurations by automatically calculating the optimal AUTOSAR allocation parameters.

TTAutomotive said its AUTOSAR FlexRay stack and configuration tool have been selected for an advanced commercial production program. The FlexRay driver is a core component of the AUTOSAR FlexRay stack and part of the microcontroller abstraction layer. Together, with the FlexRay interface within the communication ECU abstraction layer, the FlexRay driver provides a hardware-independent API to access the FlexRay controller. TTAutomotive also offers components for the services layer, including a COM layer, a protocol data unit (PDU) router and a transport protocol component. The network management component adds wakeup and sleep functionality to the cluster. The components are optimized for synchronous operation and feature a small footprint, low latency and deterministic response times.

In April, Vector Informatik introduced FRstress, a hardware module for testing FlexRay buses (Figure 5). The tool is said to stress and disturb FlexRay buses in a targeted manner by generating protocol errors and manipulating the bus physics.

“FlexRay is not a simple protocol,” noted Jim Shockey, 16/32-bit automotive MCU product manager at Freescale Semiconductor. “Migrating from event-driven to time-driven communication is a paradigm shift that will take some time.”

But FlexRay is in production and deployment of buses faster than today's CAN and LIN is inevitable.

ABOUT THE AUTHOR

John Day writes about automotive electronics. He holds a BA in liberal arts from Northeastern University and an MA in journalism from Penn State. He can be reached by e-mail at [email protected].