Electrons on Wheels

A 2005 model vehicle, such as the popular Ford F-150, can easily integrate 20 electronic modules. The control systems receive inputs from at least 50 sensors, provide outputs to control over 40 actuators, and share data over three networks. But for the most part, drivers and passengers are not even aware of these digital systems. Far more attention is paid to the high-performance audio, video, and telematics—the digital infotainment in today's vehicle.

Both digital control and digital consumer electronics make each new model year's vehicles environmentally cleaner, more fuel-efficient, safer, more secure, more comfortable, more entertaining, and even better informed. Vehicle differentiation demands annual improvements in many, if not all of these areas in an increasingly competitive market. Today, microcontrollers (MCUs) and digital signal processors (DSPs) provide the brains in the digital car—especially for the control systems. As information increases for the info portion of infotainment, microprocessors (MPUs), which have limited integrated memory and onboard I/O, will increase.

MCUs and DSPs in the Digital Car

The digital applications in the vehicle, power train, body electronics, chassis, safety security, driver information, and infotainment, all place different demands on the digital computing portion. Products from four suppliers demonstrate the differences, which range from 8-bit to 32-bit MCUs and 16-bit to 64-bit DSPs. The newer consumer electronics in telematics and infotainment have raised the ante for digital processing.

Digital Entertainment

At present, the use of consumer electronics in the car includes DVD, DVD audio, MP3 players, telematics with global positioning systems (GPS) input, satellite radio, and digital radio. Most of these systems appeared as after market products before carmakers install them as original equipment.

In the near future, there will be vehicle connectivity, including digital ports for USB and FireWire. BMW has already demonstrated linking an Apple iPod to the vehicle's audio system. "Basically what connectivity is going to be about is MP3 or other compression algorithms, storing content both video and audio, TiVo-like functionality coming from satellite, broadcast or memory stick," says Jack Morgan, Senior Director, Automotive Marketing and Sales for North America, Philips Semiconductor.

One of the key changes coming for audio entertainment is HD Radio, the standard for digital radio in the U.S., broadcast concurrently with traditional AM and FM signals. HD Radio provides near CD quality music on AM and beyond CD quality for FM. In addition, HD Radio eliminates the reception problems, channel interference, and time delay associated with FM signals bouncing off buildings. HD Radio opens the door for additional digital content in the vehicle. Initially, users see the song title and author with the music, and a broadcaster can send multiple channels and content. HD Radio requires digital IF processing.

DSP technology provides an estimated 40 percent of the overall signal processing in today's car radios. Audio processing was the first portion of the radio to go digital. "This allowed equalizing the passenger compartment so the best possible sound was obtained from the speaker system that was involved," Morgan says.

Today, a typical high-end HD Radio has six DSP cores. For example, Philips' SAF7730 combines five DSP cores for IF processing and audio processing. Two DSP cores provide the audio processing, and the other three perform the digital IF processing and digital interfacing for the radio for the I2S bit streams in the radio. One of the outputs from the DSPs goes to a separate HD Radio converter. There are digital signals in the sidebands for HD Radio, so the digital IF processor extracts the digital bit stream from the sidebands. Philips uses an ARM9 class processor in their HD Radio converter. The SAF3550 represents the first product designed specifically for HD Radio, a first step in up integration from the standard products designed in the initial HD Radios. The next step integrates this functionality with the rest of the processing in the radio, which is what Philips is currently evaluating.

Headphones with Surround Sound

To achieve an optimized surround sound environment for audio, automakers turn to companies such as Dolby Laboratories. At CES 2005, Dolby Laboratories along with technology partners Boston Acoustics and Visteon announced Dolby Pro Logic II, DVD-Audio, and the first wireless Dolby Headphone solution for automakers. To develop the technology, Dolby works closely with the semiconductor makers, such as Freescale, Texas Instruments, and Analog Devices who implement the codec and software.

Dolby developed a more efficient codec specifically for automotive applications that makes its implementation in the IC more compatible with vehicle requirements. As a result, the Dolby headphone achieves a simulated 5.1-channel surround sound through any set of headphones. The technology takes any five-channel signal and adds the Dolby Headphone processing. The signal applied to psychoacoustic algorithms converts the five channels of audio into a stereo pair, but maintains all the room configuration experience. The listener hears a room signature as if the two-speaker headphone was a five-speaker system with depth for the center speaker and sounds that seem to come from behind. What the software accomplishes, says Patrick Artiaga, Director of Automotive Marketing, Dolby Laboratories, is "tricking the brain to thinking there is something there when it is not."

Are We There Yet?

With all of these advanced systems, the digital car may have already arrived. Even a digital computer is, at best, only 90 percent digital—the rest being analog components for power supplies, displays, and peripherals. However, the percentage of electronics in a high-end luxury vehicle is not even a third of this level.

"The evolution of the digital car is well underway and we see the market trend moving toward more autonomous capabilities integrated into the design, especially related to safety and infotainment," says Peter Schlumeyer, Director of Strategy & Marketing, Freescale Semiconductor's Transportation & Standard Products Group. "Cars will increasingly have electronic systems that are able to act on their own without the driver or passenger having to activate them."

Philips' Morgan agrees that the action is in the entertainment portion of infotainment. "In my opinion we have a long way to go, but it will be more about entertainment in the future and making the car a truly comfortable living space comparable to your living room in terms of entertainment amenities," Morgan says. "That's going to be the end point and we still have lots of years of development to get there."