Automotive networking puts cars on the fast track for safety, comfort, and better environment

In-vehicle networking is creating a quiet revolution in automotive technology. It has eliminated bulky wiring harnesses once used for control circuits and enabled dozens of convenience features such as anti-skid braking systems, airbags, engine control, transmission control, and electric power steering.

In the future, networks will deliver operational data such as lane departure warnings and road condition advisories while allowing drivers and passengers to enjoy their journey more than ever before. Networking is also critical to environmentally friendly hybrid vehicles, which depend on fast, reliable inter-communication between components. Battery systems need charging and power management, and hybrids also require precise coordination between the electric motor and gasoline engine.

LIN, CAN AND FLEXRAY

Today’s dominant in-vehicle networks are local interconnect network (LIN) and controller area network (CAN). The newest automobile network, FlexRay, has only recently appeared in cars – but is sure to grow in importance.LIN is perfectly suited for local control operations such as actuating door locks and electric window controls. LIN’s low data rate (20Kbps) prohibits its use in more sophisticated and data-intensive applications such as motor control, braking and suspension systems. CAN dominates those applications, and it comes in three flavors – fault-tolerant, high-speed, and single-wire, used mostly by General Motors.

Within the next year or two, FlexRay will begin its significant market penetration. FlexRay is a deterministic high-speed (10Mbps) network perfect for time-critical applications. Figure 1 illustrates representative applications for CAN, LIN, and FlexRay.

Figure 2 illustrates how market segmentation for in-vehicle networks will change over the next few years in terms of individual network connections or nodes. Each node represents an electronic control unit (ECU) that controls mechanical systems.

Overall market for automotive networking will grow at a 10 percent annual rate through 2011.

NETWORKING TRENDS

In addition to nearly doubling by 2011, the networking market will experience other significant changes. The primary driver of LIN’s growth is its use in more convenience systems such as adjustable seats and mirrors. In other words, the gap will narrow between the average vehicle, which now has 15 ECUs, and high-end vehicles with 150 or more ECUs.

Another growth factor will be hybrid vehicles, which now represent a small percent of total car sales but are expected to steadily increase market share.

Batteries must be re-charged during the braking cycles and the motor itself is constantly tuned to achieve its most efficient performance. The complexity of the task of managing two drive systems – internal combustion and electric – explodes in hybrids. Hybrids will likely utilize CAN for these functions.

Another trend is that automotive engineers are constantly looking for ways to combine the functions of multiple ECUs into one to reduce complexity. This trend presents semiconductor companies with both a challenge and an opportunity. On one hand, collapsing functions into a single ECU typically means more than one transceiver per ECU.

But there is no particular need to replicate components such as voltage regulators and watchdog timers. IC companies such as NXP are therefore integrating more functionality into their transceiver products. Besides reducing costs, these sophisticated components give electronic module suppliers and carmakers more flexibility and scalability.

NXP Semiconductors’ UJA1061 and UJA1065 families, for example, integrate discrete components with a LIN interface and a CAN interface. The UJA1061 family uses fault-tolerant CAN and the UJA1065 family uses high-speed CAN. Besides being cost effective, integration makes certain fail-safe safety features possible because smart transceivers can isolate malfunctioning nodes.

FlexRay is now being used to control single systems such as suspension control in BMW’s X5 SUV. That system is based on NXP’s TJA1080 transceiver. FlexRay will grow quickly, however, and has received wide interest from all major car manufacturers.

COMPLETE SOLUTION

Networks improve automobile functionality and reliability and simplify control compared to point-to-point communication. But the network itself is becoming more sophisticated. As a result, automakers increasingly expect semiconductor companies to provide complete solutions.

Interoperability is a concern. Transceivers, in particular, are sensitive devices that must operate in the harsh automotive environment that includes heat, electro-static discharge (ESD), and electro-mechanical interference (EMI).

The complete solution involves application engineering support and services such as simulating proposed network topologies. Assistance in configuration and system partitioning is another area where IC companies can step in when simulations indicate re-engineering is in order.

Complete solutions must look beyond the automobile rolling off the assembly line. Imaginative IC companies can supply valuable assistance to car and module manufacturers during manufacturing. One example is providing high-performance ESD protection components to protect the modules.

In extremely dry environments such as manufacturing floors, sparking can occur when ECUs are being shipped, handled, and installed. Supplying protective devices such as NXP’s PESD1FLEX, PSED1LIN and PESD1CAN diodes that provide protection up to 23kV can solve this problem. Optional ESD protection is another example of offering OEMs a complete, cost-effective solution that meets their specific ESD robustness requirements.

A LOOK INTO THE FUTURE

Largely through the expansion of networks, automobiles will continue to provide more comfort and safety features in each successive model year. The culmination of these efforts is known as drive-by-wire, which means that every aspect of vehicle control and instrumentation will be electronic. The network will interact with the driver instead of simply relaying driver commands to ECUs.

Today, sensors mounted on the car can inform the driver of a potential collision and initiate braking. Networks of the future will be able to do much more, even to the point of taking control of any system needed to avoid a crash. The same “autonomous vehicle” functionality will also be available during normal driving so a driver can attend to other matters or simply enjoy himself.

About the author

Hans de Regt has over 15 years of experience in B-to-B electronics. As marketing director of the Business Line Automotive at NXP Semiconductors, he is responsible for $200 million sales to the automotive electronics industry.

Click here for Illustrations:

Figure 1, Figure 2