e.Digital Corporation (fka EDIG)

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Tomorrow's cars are like portables on wheels

With all the electronics packed into the next generation of automobiles, designers are finding it necessary to employ "portable" design techniques.

Richard Nass, Editor-in-Chief

You may be asking yourself why a magazine that specializes in "portable" technology is reporting on automotive electronics. The usual criteria for inclusion are that the system must be powered by a battery and contain a microprocessor, microcontroller, or DSP. An automobile certainly fits those criteria. There is, however, a much better reason for our coverage.


When you consider the amount of electronics that's being embedded in today's high-end (and tomorrow's mainstream) automobiles, it's obvious that the total power consumption must be kept as low as possible, for a few reasons, including the size and electrical noise considerations.

Automotive designers are faced with the dilemma of squeezing a lot of electronics into a small space, much like the problem faced by the designer of a notebook computer, PDA, or cell phone. There are also many different power supplies crammed into a small area.

Says Dave Bell, vice president of Linear Technology's Power Business Unit, "You have to worry about efficiency, not because of battery life, but because of the heat that's generated in a small space. On top of that, there's concern over interference issues. When you're dealing with audio and video, you need to keep the switcher noise from interfering with the FM band or producing wines and buzzes in the audio."

Industry analysts estimate that the total amount of electronics in the car will increase from last year's $89 billion to $121 billion this year. Part of this is in engine control, part is body control, etc. But the area that's growing the fastest is the entertainment, or telematics, area. Semiconductor content increased from $199 to $239 in 2000. That's just semiconductors, not total electronics. High-end cars, like Mercedes and BMW, now have more than 60 embedded microcontrollers.

A problem with the high semiconductor content is that some of these controllers remain on, even when the car isn't running, such as the security system. Even if the power draw is fairly modest, if the car isn't used for a few weeks, the battery could be drained.

Helping to combat this problem are some fairly rigorous standards for low quiescent current on devices like switchers and converters. For example, the LT1766 dc-to-dc converter, developed by Linear Technology, has a standby current that's below 100 µA.

Safety first
The latest electronics in the telematics arena are designed to connect the driver to the car, as well as to the outside world, but to do it in a manner that keeps the driver's hands on the wheel and eyes on the road. In Japan, the telematics place an emphasis on navigation, where the primary objective is how to get to and from different addresses. In the U.S., safety is the primary application. In Europe, the focus tends to be a combination of the two.

One way to link the driver to the car is to connect the portable devices that tend to be used there, such as a cell phone or PDA. By combining a Bluetooth link with voice activation, the task of using the phone in the car is greatly simplified. Going one step further, connecting the car-phone combination to the PDA could add a voice-activated calendar and address directory, which could be connected to the navigation/GPS system. So when you tell the car you want to go to a particular destination, it knows where you are and how to get there.

Texas Instruments recently released an IEEE 1394b bus solution that supports in-car infotainment applications, such as rear-seat entertainment. This solution works in conjunction with the company's Bluetooth chipsets. The IDB-1394 technology supports 1394b at 100 Mbits/s over 10 m of plastic optical fiber (POF) or unshielded twisted pair, category 5 (UTP5) cable. Developers can then choose between POF, which minimizes electromagnetic interference (EMI), and UTP5, which reduces overall node cost. The Bluetooth chip sets enable hands-free car kits, and when used with the IDB-1394 bus, allow for complete advanced telematics communications in automotive applications.

Available processing power
NEC produces a family of automotive-based microprocessors that fit into the non-mission-critical space. It covers infotainment (information plus entertainment) features like voice activation, multimedia applications, and the navigation and entertainment systems.

The 64-bit MIPS-based VR4181A processor integrates more than 18 peripherals and interfaces with a VR4120A processor core. It can handle voice-activated and Internet-application systems, as well as audio systems that require a display. The interfaces include I2C and I2S.

At the high end, NEC offers its Vr5500 family, which are suited for three-dimensional applications, such as navigation systems and virtual dashboards, ones that are user configurable and contain no gauges.

The NEC automotive-based devices are specified over the full automotive spec range, -40°C to +85°C. "Most consumer companies will only cover an ambient temperature range of 0°C to +70°C. That's all they'll guarantee," claims Kevin Tanaka, staff product marketing engineer at NEC. "For our parts, we are covering the full automotive spec range, and we ensure that we can cover the 10- to 15- year life spans that the automotive systems require."

STMicroelectronics has developed a processor that specializes in voice recognition in automotive applications. The Euterpe digital voice processor includes a DSP core that's optimized for audio applications, analog-to-digital and digital-to-analog converters, code and data memory, external memory management, and an I2C interface for communication with a host processor.

Using third-party DSP code, the Euterpe can perform speech recognition, text-to-speech, speaker verification, noise suppression, echo cancellation, and other voice-processing functions. Developers can also add their own code to diversify their products.

Bringing information to that processor is the specialty of Philips. "Our business concentrates on the transceivers, the part of the bus that translates the currents and voltages into digital signals that go to the microprocessor," says Brian Brewster, strategic marketing manager for Philips Semiconductors' Automotive Business Line.

The buses that carry that information include the control buses, CAN, LIN (local-interconnect network), and some emerging buses, including one for air bags. But those buses are continually changing. CAN essentially dominates in Europe, and is becoming more popular in North America and Japan. Although CAN is relatively slow.

Brewster continues, "People don't realize how many different nodes there are in a vehicle, particularly in luxury cars. The problem of linking all these is becoming quite an issue. It can get a little scary when you look at the complexity of these vehicles."

Passing the test
As far as testing is concerned, IFR Systems has an assembly-line approach that checks the installation integrity of the infotainment subsystem. The system is a collection of RF test equipment that couples to antennas mounted above the vehicle. It sprays the vehicle with test signals of a controlled and precise level (see the figure).

"We're not trying to measure the performance of the radio and other items. That's done exhaustively by the component manufacturer before the device is shipped to the assembler," says Tony Rudkin, a business manager for systems at IFR. "We're testing the process, not the component. The main concern for us is the cabling, the antennas, the items that the manufacturer (assembler) fits to the car.

"Manufacturers are surprised that we are failing cars that they thought were okay," continues Rudkin. "Because our test is more rigorous than the tests people did before— which, in many cases, is to drive the car out of the plant, listen to the radio, check that the phone works by calling a base station, etc.—we're testing the car at the limits of its sensitivity range. So it replicates what would happen if you drive the car well away from a base station or broadcast station, when you're on the edge of the service area."


By spraying a vehicle with test signals of a controlled and precise level, the installation integrity of the infotainment subsystem can be checked.
Microsoft is trying to tie together some of the non-mission-critical systems in the automobile with its latest incarnation of Windows CE, aptly named Windows CE for Automotive 3.5. This version covers areas such as hands- and eyes-free communications, speech recognition, robust graphics capabilities for faster map drawing, faster start-up times, and reliable Internet access.

Motorola, one of the pioneers in automotive electronics, provides the brains for the engine controller, as well as the controller that remembers how and where the driver likes his seat positioned, and the airbag sensor. The company is also working on features like automatic cruise control, where the speed can automatically be adjusted based on traffic conditions.

"Our portion isn't necessarily to implement these changes, but to provide the building blocks that allow these changes to occur," says John Hansen, director of marketing for driver information systems at Motorola.

In the automotive industry, there are essentially three reasons why any new electronics or capabilities of any type are introduced. One is that a new technology can do the same job more cost-effectively. Second is that the perceived value reaches a high enough level. For example, if a new feature allows the car dealer to increase the price of the car by a high enough percentage, then it makes sense. And the third reason is legislation.

An example of where legislation comes into play is in the tire-pressure monitoring system (TPMS). This is a mandated technology for all 2003 model cars that puts a sensor, a microcontroller, and a transmitter into each tire. The system monitors the tire pressure and transmits that information to a central location in the car. The information is then available to the driver, particularly if a problem arises. The technology is similar to what's used for the key fob, the remote keyless entry that unlocks the doors. The information is sent over an RF link.

Moving to 42 V
Another area that's under investigation for automotive designers is the use of 42-V electronics. A level of 42 V was chosen because it equals three batteries in series. In addition, under 50 V is generally considered a "safe" range, although the hybrid cars on the road today run at a higher level.

Two or three years ago, experts predicted that 42-V cars would be here today. However, the evolution has taken longer than expected, and it will be another three or four years before these vehicles are in production. The need for the higher voltage stems partly from the amount of higher power electronics coming to the automobile, things like electric steering, brakes, and valves.

In the first generations, there will probably be hybrid 12- and 42-V cars. The use of dual voltages will result in a need for high-power converters to go between 12 and 42 V. Some things simply work better at 12 V, such as the headlights and incandescent bulbs in the car. Component designers claim they can make more rugged headlamps with the thick filament that runs at12 V, compared with what's needed at 42 V.

Linear Technology's LT1339 is an example of a high-power converter that will work in a 12/42-V system. Says Linear Technology's Bell, "Many of our automotive customers are looking at doing a three-phase LT1339 device, where they would drive three of these parts phase-locked to each other to build a 1.5-kW converter."

While there's agreement that cars will go to 42 V, there are some differences of opinion as to why the change will occur.

"You hear stories like, 'We need higher voltages because there are so many electric loads on the car, we can't cope.' That's not necessarily true because you can just make a bigger alternator at 12 V, unless you have an incredible amount of load," claims Steve Clemente, a senior technologist at International Rectifier. "The most important reason to employ a hybrid system like this is for fuel efficiency."

Going to 42 V will enable the use of an electric motor to handle the "start-stop" functionality. In other words, when you stop at a traffic light, the engine shuts off completely. When you push on the accelerator, an electric motor gets the car going and starts the engine.

When the car isn't running, the power comes from a battery. Before you reach the next traffic light, you recover the consumed energy and recharge the battery. If the battery gets to a point where it really gets discharged, then the engine would be recharging the battery during normal operation.

Such a hybrid system will allow for the use of smaller engines. If more power is needed, the electric motor can be used as a boost.

A 42-V car also makes it easier to integrate a "drive-by-wire" system. This is a term that's been thrown around lately, and means different things to different people. But in general, it's the move from mechanical control linkages to electronic linkages. Take the steering, for example. Instead of having a physical connection from the steering wheel to the wheels, you'd have an electronic sensor that would sense movements in the steering wheel.

Before something like this can be implemented, it must be extremely reliable. One drive-by-wire standard calls for dual message sourcing, so that each message is sent twice. Error checking and correction is also done to ensure that the proper message is sent and received.

Another key feature is the need for a graceful fix. This means that some backup system must be employed, rather than having a system (like the steering or brakes) simply shut down. For example, in today's power steering technology, when the power steering mechanism fails, the driver can still steer the car. It's more difficult, but it can be done.

The next step would be to have the car drive itself. "That's in the research stage today," says Motorola's Hansen. "It's one thing to be able to get a car to drive around a test track. It's a very different thing to have a non-human-driven car react if a ball jumps out in the road. How will it know that there might be a child coming right after that ball? A computer-controlled car isn't there yet."

IFR Systems
Wichita, KS
[phone] or [phone]
www.ifrsys.com

International Rectifier
El Segundo, CA
[phone]
www.irf.com

Linear Technology
Milpitas, CA
[phone]
www.linear.com

Microsoft
Redmond, WA
[phone]
www.microsoft.com/automotive

Motorola
Austin, TX
[phone]
www.motorola.com/semiconductors

NEC Electronics
Santa Clara, CA
[phone]
www.necel.com/microprocessors/index.cfm

Philips Semiconductors
San Jose, CA
[phone]
www.philipssemiconductors.com/markets/automotive/ivn/

STMicroelectronics
Lexington, MA
[phone]
www.st.com

Texas Instruments
Dallas, TX
[phone]
www.ti.com

Portable Design April, 2002
Author(s) : Richard Nass
http://pd.pennnet.com/Articles/Article_Display.cfm?Section=Articles&Subsection=Display&ARTIC...
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