Automotive infotainment systems are very important to vehicle manufacturers today. However, the manufacturing of these systems is becoming increasingly complex, time-consuming, expensive and error-prone due to widely varying proprietary technology and very different vehicle development cycles in relation to consumer electronics. Infotainment systems in the future can only be more cost-effective if they are built on standardized platforms that are comprehensively used and reused by both the manufacturer and the supplier, eliminating differentiation caused by the use of different base technologies, differently designed user interfaces, and configuration of applications for each vehicle.

Standardization and repeated use significantly reduce manufacturing costs and development time for base technology as well as for specific innovation; quality also increases proportionately. The value-added chain as well as business models must be approved correspondingly and demand greater focus from all partners on the respective core competency.

Open Source Linux

The open source model such as Linux offers excellent support for fast innovation. Ready availability, standardized drivers and open interface standards create the basis of a development community that includes many people, companies and organizations. This community and its projects and solutions, together with commercial solution providers, create an ecosystem that continues to expand. This huge ecosystem provides the basis for application development. An example of such a community is Moblin, whose theme is "in-vehicle infotainment." Reuse and adjustment move into the foreground; new development takes place only where added value is produced. The developer can focus on innovation instead of having to reinvent the software infrastructure for each new project.

However, the use of Linux and open source for embedded systems has always given rise to challenges. Size, complexity, startup time and licensing problems with the GNU Public License have been obstructing factors. Now that the code and file size of the software in relationship to the size of the processed (and partially stored) data are no longer serious problems, these issues in regard to Linux-based in-car infotainment are being addressed along with other issues specific to the vehicle environment.

The requirement is for a robust and stable platform, with a sensible set of components as the basis for quick development of innovative applications. Open application programming interfaces must enable the integration of additional applications. Open standards help primarily with the investment protection of these applications. Also, a high-performance test environment must be available under open source.

In addition to novel applications, a standard platform would, moreover, pave the way for vehicle manufacturers and suppliers to offer new business models in preparation for new functions or software upgrades as part of routine maintenance. These could be installed via downloads. Error corrections, a new application or a new plug-in for existing applications (e.g., a codec for a new video format) can be installed in the vehicle in this way. The development of navigation devices illustrates the possibilities. In addition to the actual devices, there is an emerging market for cards and other applications. Similar developments are to be expected from in-car open source: numerous applications in the shortest possible time for a whole series of consumer devices.

Linux In-Car Systems

Linux in-car infotainment must provide a set of standard functions that are considered to be a basic infotainment requirement. These include applications such as speech recognition, Bluetooth, powerful solutions for echo and noise suppression, connection options for devices such as MP3 music players and multimedia support for a wide range of electronic entertainment devices and video and audio standards. Internet applications and services such as Google Earth and YouTube can be used in connection with in-car integrated navigational systems or mobile navigation systems. The user also expects solutions for music management and play lists as well as multimedia and DVD solutions.

p>

Figure 1: Linux in-car infotainment overview

These types of systems are available in the open source community and have already been transferred to the PC market. The previously mentioned ecosystem helps in this area. However, the automotive market needs a complete test environment to ensure that applications are integrated quickly and correctly and to identify possible interoperability problems. Reference systems such as Russellville, based on the new energy-saving Intel Atom processor jointly supported by Intel and Wind River, ensure that developers can concentrate on their applications and on creating useful user interfaces rather than to first spend time creating a development platform.

Interoperability

One topic of special interest is the interoperability of infotainment systems with consumer electronic devices. These include mobile phones connected via Bluetooth and devices such as the Apple iPod music player and others. These devices are characterized by short life cycles. The challenge is to ensure interoperability beyond these life cycles. The open source community addresses this as do commercial solutions such as the Parrot Bluetooth, which ensures wide compatibility with current mobile phones through adequate testing. Another important issue is freedom of choice between open source and commercial offers, the pros and cons of which require individual evaluation.

A key architecture concept frequently adopted by Linux is the use of so-called plug-ins. Combining a wide variety of underlying devices, interfaces or software modules in a standard API and standard processing logic allows flexible and simple plug-ins to respond to modified types of devices and protocols and so on without having to renew the application software above the API. This concept is ideal for our fast-living consumer world: All that is required is a simple plug-in replacement or addition when a new mobile phone, iPod or other consumer device comes on the market.

Power Supply

A special technical requirement of in-car devices is the power supply management and fast on/off switching. On/off switching takes place by means of individual steps that do not always follow the same sequence. For instance, switching off the ignition while listening to music or conducting a hands-free conversation makes a difference. Users may also spontaneously change their minds and interrupt an activation/deactivation, which will interrupt the on/off process. The voltage supply (car battery) cannot guarantee a constant power supply. This is no problem with PCs and laptops, but in a vehicle it is of critical importance because a complete device failure due to a temporary power loss (ignition) cannot be tolerated.

Figure 2: Power management, part of the finite state machine

In this case, the Linux community does not provide a "complete" solution. But because these problems are familiar to in-car software, the required methods are known, have been tested and can be provided by Linux for in-car infotainment. A finite state machine with flexible status determination and trigger signals is a component of Linux in-car infotainment that solves the problem. The finite state machine also forms the basis for the booting and shutdown process of Linux itself. Open source component rebooting is used here. Rebooting also provides the basis for fast booting. However, reducing the booting time to an absolute minimum requires, as with every other platform, a great deal of experience and depends on the specific circumstances of the end system.

Audio and Video

In addition to numerous modern comfort functions, the processing of audio and video signals is a central task of in-car infotainment systems. In addition to classic sources (radio, CD, DVD), Web-based sources (Web radio, YouTube, Internet TV) are becoming more prominent. Camera signals from driver assistance systems also require inclusion. The latter require the quality processing of a large number of audio/video formats. The open source community offers a large number of codec implementation formats. There are also numerous media players and multimedia applications. Player logic, user interface and the audio/video pipeline are more or less strongly interfaced here. In this particular case, the licensing situation must be addressed as well as the question of whether patent fees to third parties (e.g., MP3) are due. An interesting implementation is the Helix DNA client media framework from Real, which is based on its RealPlayer.

Figure 3: Audio management, audio connection manager switches or connects audio channels to various audio busses, for example, MOST

A specific topic for in-car Linux is multichannel audio and video processing, with the aim of including front-seat as well as rear-seat solutions. The driver takes care of navigation whilst a video is playing for the rear-seat passengers. This can be implemented via a separate infotainment system or it can be developed as a part of the driver's system or the "head unit" system. The introduction of multicore makes this possible from the CPU load point of view.

An incorporation of the head unit into the (electronic) display panel would also result in several displays. The graphic/video aspect is already well controlled by the popular Linux X11 system with suitable drivers. Management of multiple audio channels is an additional functionality that must be provided. This includes the specific possibility of granting different audio sources different priorities. Entertainment must, for example, be interrupted to give priority to an incoming telephone call, a navigation system announcement or a warning signal generated by the vehicle, such as an alarm signal.

Networking

The infotainment system is much more a networked system than is a PC. Depending on the specification (e.g., rear-seat entertainment), it is also a distribution system. Linux in-car infotainment can use solutions from the Linux community, as servers often use distributed Linux systems. These include wireless networking via Bluetooth, Wi-Fi and WiMAX. Linux in-car infotainment must provide additional connection options and interoperability with automobile network standards such as Controller Area Network or Media Oriented Systems Transport as well as the ability to support future technologies such as FlexRay.

With their multitude of software components and application systems, infotainment systems are complex by nature. This applies to in-car integration as well as software structure. Rest bus simulation and network protocol analyzers support networking processes. Standardization and the use of proven and tested software components support the device software. This is supplemented by powerful development tools such as Wind River Workbench, based on Eclipse. In addition to the classic compile/edit/debug cycle, Workbench pays particular attention to the efficient configuration of the device software (Linux kernel, components) and the analysis of the entire system's operating characteristics.

Licensing

In the past, the open source community has often voiced reservations concerning the type of licensing involved. The GPL is not used exclusively but is for the majority of components. This applies, for example, to the Linux operating system and many of its components. However, some applications are also covered by the GPL. The GPL governs free use, subject to the disclosure of results, and has greatly contributed to the success of open source and the large Linux community. At the same time, companies are reluctant to disclose their software sources. This risk becomes greater as software is more intimately connected to the Linux kernel. Drivers, a typical example of software basics, are thus very often designed as extensions of the Linux kernel. It is debatable whether such kernel extensions should be disclosed to the GPL under the licensing regulations of the Linux kernel. However, application software usually runs as a process that is disconnected from the Linux kernel via standard interfaces. Libraries in turn mostly use extenuated licenses (e.g., the GNU Lesser Public License), which require the disclosure of the library code but not of the applications themselves.

With the transferal of added value from the platform to the application software and total system integration, Linux in-car infotainment users find themselves in a good position. With experience, safe dealings with the GPL will be ensured. As with other application areas of Linux, companies are prepared to disclose formerly proprietary application software conscientiously and without undue prompting and create added value via the open source community.

Standardization of the Environment

Linux is increasingly used by standardization organizations. As an example, the OpenSAF Foundation uses a commercial Linux version as a basis for software architectures for the telecommunications branch. As a result, a software model integrated mostly vertically to date is now being converted into a more horizontal model, where new users offer a wider range of innovation applications that still comply with the stringent performance and quality requirements of the telecommunications industry. The same is possible within the automotive industry. Organizations such as AUTOSAR, a software standards organization, develop a selection of applications that will subsequently form the heart of a standard version. The Vehicle Infrastructure Integration Consortium chose Linux as its run-time and development tool for an onboard equipment prototype. VIIC is supported by the U.S. Department of Transportation and targets the improvement of road safety with the aid of standardized driver communication.

Platform for In-Car Infotainment

Wind River has chosen to tackle the subject of open source-based infotainment and has created an open vehicle infotainment platform together with Intel and software partners such as Gracenote, Nuance, Parrot, and Planet 9. Wind River contributes its knowledge of Linux as device software as well as its longstanding experience with in-car software. Wind River offers Wind River Workbench and Wind River Linux platforms as well as service, support, and training. Specific vehicle-related challenges are addressed with Linux and open source community solutions. Power status management, persistency management, diagnosis management, vehicle-specific software update management, connections with rest buses such as MOST and CAN and automotive-specific audio/video management are available.

The platform for in-car infotainment is accessible as open source at http://www.moblin.org/community/ivi/. It has been developed further by Wind River and participating partners. Everybody is welcome to contribute to and participate in the future development of Linux for cars.

Alexander Kocher is General Manager for Automotive, Wind River GmbH, Karlsruhe, Germany. Peter Kleiner is Senior System Automotive Architect for Wind River GmbH, Karlsruhe, Germany.