How To: Build an In-Car PC

For this Recipe, I'll feature both components that are built specially to handle the rigors of a road trip and those that can also work on the desktop. On the dashboard, here's how a typical build will look:

Pretty cool, right? Ready to get your clients in gear with a car PC? Then let's roll!

Why Mini-ITX?

Mini-ITX is an ultra-compact motherboard developed by VIA Technologies, a Taiwanese company known for innovation and high-quality manufacturing. The highly integrated features of mini-ITX mainboards are ideal for building systems that are powerful, quiet, and small. These boards also pack all the punch of a full-sized PC while running far cooler and more quietly. These features have made mini-ITX solutions the most popular choice for embedded applications and appliance computing—in short, any place where space is an issue.

We'll add to this compact, solid mainboard a road-worthy case, rugged hard disk, and a power supply built to handle special automotive needs, such as battery drain. Put it all together, and you've got one solid Car PC that's ready to hit the highway in ways that no desktop box or notebook could.

As with any technology, there are tradeoffs. So let's talk about the pros and cons of implementing a Mini-ITX solution for the road. I think you'll agree that the pros far outweigh the cons! Here's a brief summary of the highlights of working with a mini-ITX:

• Ultra Compact: Offers a 170 mm x 170 mm (roughly 6.7 in. x 6.7 in.) form factor.
• Highly Integrated: Boards carry an onboard processor and integrated I/O.
• Power Efficient: Low power consumption, cool operation.
• OS Compatible: Systems support Microsoft and Linux operating systems.
• Modular: Integrates with industry standard components.
• Secure: Mini-ITX boards feature onboard encryption technology.
• Quiet: Smaller means less noise, and fanless mini-ITX offer less noise with greater stability.
• Compatible Interfaces: Supports SATA drives, DIMM memory, PCI cars, and both USB and Firewire peripherals.

On the flip side, here are a few limitations on the technology which you should consider before implementing a mini-ITX solution:

• Not Upgradeable: To reduce the cost of manufacture, CPUs are permanently installed on the mainboard. The ZIF (Zero Insertion Force) socket on most modern motherboards makes up a significant part of the manufacture cost. In VIA's EPIA (Embedded Platform Innovative Architecture) architecture, the company integrated the mainboard and CPU and removed the socket to streamline production and reduce costs.
• Limited Expandability: Typical cases have limited real estate—that's the cost of going "small." Power supplies can be as small as 60 watts, limiting the addition of peripherals. Also, these boards have minimal PCI slots available.
• Higher Cost: The cost for an integrated mini-ITX mainboard is likely to be higher than a comparable ATX motherboard/CPU bundle.

While there are certainly some cons to going with mini-ITX, I believe the technology is sound. That's why I recommend it as the virtual heart of this build.

Car PC Benefits

The public's attitude about what belongs in a car, coupled with technological advances that have made components like displays more compact and robust, have transformed cars and SUVs into rolling infotainment centers. Not long ago, a video display in a car would turn heads; today, it's commonplace. Global positioning systems (GPS) that were once deployed exclusively by the military now listen for bleeps from space from consumer dashboards. DVD players, surround sound, and video displays have all become popular selling features for auto makers. Add to that the high-end options: satellite radio, Bluetooth connectivity, rear-view cameras, vehicle diagnostics and sensor monitoring, Wi-Fi, smart alarm systems, and more. As a result, consumers seek new possibilities for their mobile computing needs.

Car dealers and makers of satellite radio, GPS and media players are targeting a growing consumer market with individual infotainment products. But a well-built car PC can run all of these and more. It can also help consumers with route planning, Web browsing, personal scheduling, gaming, and general computing.

System builders should consider consumers to be just part of whom you should pitch for offering a road PC. There are also hardcore mobile computing applications you could offer, such as digital video recording for police vehicles with broadband connectivity. Also, consider inventory and transportation tracking systems for trucking and delivery companies that provide businesses the advantage of being able to pinpoint where their products and materials anytime anywhere.

Let's take a look at some approaches to getting a PC on the road and choosing the right components. Then I'll show you how to put it all together.

Why Not Go With a Notebook?

In-car PC components are similar to those for notebook and desktop systems—power supplies, CPU, hard disk, etc.—but they need to meet much more rugged specifications. The operating environment in a car is vastly different from an office desktop. Notebooks, while closer in size and ruggedness, are still best for home or office use.

Can you simply mount a notebook or desktop and use it in a car? Sure, and many installers have done just that. But there are serious drawbacks. Desperate installers have mounted flimsy desktop cases in the trunk; used inefficient power inverters to supply power; and even have built elaborate trays for input devices. But size, cable runs and cooling requirements make the desktop approach cumbersome to install and unappealing to operate.

Where standard desktop boxes are awkward for the road, notebooks are a better fit. But their power supplies are not specifically built to handle the special demands of the starts and stops of an average vehicle. As a result, an unmodified notebook cannot be counted on for reliable in-car service.

In addition, both traditional desktops and notebooks are plagued with overheating problems and unexpected reboot issues. Inopportune reboots can occur as power fluctuates in a system designed more to provide power for a car's lights, wiper motors and fans than the smooth, constant voltage required for typical computing. Car PC's Require Special Components

A reliable in-car PC needs to use small yet rugged components whose size and shape allow proper placement, whether on a crowded dashboard, in or under a dashboard, or under the car's seats. The PC needs to be out of the way of the car's critical instruments.

A car PC must also be designed to be a real workhorse. It will need to handle heat and cold, exposure to sunlight, rapid changes in temperature and humidity, along with shocks and vibrations from the road. The system must also survive as an add-on to a power system that is frequently switched off, often for long periods, and that is prone to deep cycle discharging.

Automotive electrical systems—unlike the clean, steady household current from a wall receptacle—operate off a DC (direct current) storage system that is constantly changing. First, it discharges to deliver power to 'turn-over' a cold car engine. Then it charges the battery back to capacity as the car is driven. Car PCs must operate from power fully conditioned to remove the risk of low voltage during cranking and carefully regulated to prevent damage to PC components during charging.

In summary, an in-car PC must work consistently and meet the challenges of in-vehicle operability. It must be able to take a beating, have short boot times, offer power-saving features, and run its applications easily and safely accessible. The system must be mountable where it is easily visible but doesn't block the driver's line of vision or the path of airbags. The system also must be fastened securely so it won't come lose in a minor accident.

To meet all these challenging requirements, you'll need to choose the right components. In the next section, we'll look at your best choices for parts and how to source them.

Getting the Right Parts for a Car PC

Finding the right parts for your car PC is all about heat, power, vibration/shock, and operability. Let's take these in order:

Heat: Large power requirements and heat dissipation don't mix well with the confined space of a car. As a result, traditional desktops are difficult to keep cool in a car. Notebooks require less cooling, but mini-ITX boxes are even better. They're also easier to tuck into tight spaces. At just 17 cm. x 17 cm., a mini-ITX can fit into or below a dashboard, or even in a glove compartment. Special enclosures, like the VoomPC case, allow for optimal cooling and shock resistance while keeping a compact footprint; I'll discuss this at greater length later in the Recipe.

Power: This is the most challenging obstacle to computing on the road. Specifically, how do you supply clean power as needed? And how do you not drain a car system's battery when the car is unattended for long periods? Inefficient power inverters can covert the 12-volt DC typically used in car electronics into the 120-volt AC (alternating current) source required for a standard PC power supply. But there are a number of drawbacks. Most notably, inverters don't "know" when the car ignition is being turned off, so PCs won't shut down properly and will constantly be restarting on short trips. While notebooks use less power and can operate without an inverter (since they operate from battery power already), they can drain car batteries if left on or in 'hibernation mode' over long periods.

An excellent solution is a new breed of power supply that can make decisions about how to supply power and even signal a PC to 'hibernate' or 'shut-down' when warranted. It's called a DC-to-DC converter, and it can covert a car's 12-volt source into the 3.3-volt, 5-volt, and 1-volt outputs that computers can use. I especially like the M2-ATX. It allows for a user-selectable timer that lets the PC to remain on for a certain amount of time after the car is shut off before issuing a command to the computer to go to 'sleep.' Then, after a prolonged period of sleep, the power supply protects the car's battery by issuing a full shutdown command to the PC.

Vibration and shock: Components in a car PC are subject to all the same jarring, bumping and G-forces as passengers are. If all users drove luxury cars on traffic-free, freshly paved highways, then vibration and shock would be a non-issue. But in the real world, potholes, debris, curbs, and sudden stops and starts can all cause serious trouble for an in-car PC. As a result, hardware mounting, cable stress and wear, and choice of hard disk need to address the situation.

The PC's hard disk is the only constantly moving part, making it the one most sensitive to road shock and vibration. Fortunately, most of today's 2.5-inch notebook drives are designed to take a reasonable amount of abuse from motion, and most are suitable for all but the most rugged applications. I recommend the Seagate Momentus 7200.1, which has been rigorously tested for use in many mobile and notebook applications. For situations where you know your car PC will be heavily stressed, Seagate's EE-25 series drives are hardened specifically for automotive applications; they should hold up better in challenging applications.

Operability: Car PC users need to get to their applications fast and with a minimum of interaction. So keyboards and mice, while handy for occasional work in the car, are of limited use in a car. Instead, car PCs should rely on touch screens and software interfaces with "skins" that let users access their apps quickly and safely.

In car lingo, a touch screen works like a "head unit," providing access to music selection or a GPS. A major goal of a car PC is to replace the vehicle's head unit with a touch screen that will act as GPS, CD player, radio and the like.

Skins used with voice-recognition software can also provide safe and a mostly hands-free method of working with applications. Applications like RoadRunner and SKINbedder work with NaviVoice voice recognition to provide quick access to applications with a minimum of driver involvement. In the screenshot below, you can see how NaviVoice helps to integrate voice activated GPS with media playing and other applications, making GPS functions available quickly and safely with a one-word command:

With applications like Mobile Media Center, users can develop their own "skins" to access media and other car applications by touch. Here's an example:

Ingredients

Here are the components you'll need to create a car PC:

The following photo is a shot of the main components: VoomPC case, Seagate hard drive, and M2-ATX power supply board for our Car PC. It also shows a Star monitor I used to check the mainboard before permanent installation of a touch screen:

Vertical mounting of the hard drives, rather than horizontal mounting, can minimize trouble from hard impacts and minimize "head crash" situations. If you know a drive will be getting serious abuse, choose a location for the enclosures that provide sufficient air flow and keep the disks perpendicular to the road. Assembling the Car PC

Before assembly, and before making final decisions on parts, make sure you have a solid plan and a proper place to work. Finding the right place to work on your car PC will make for a cleaner installation and speed your project along. Look for a protected location with good lighting. You'll also want to use a droplight to help you with interior fitting and for working under the hood. Don't forget Internet access for downloading applications, updates, etc. While garages with a high-speed hook-up might be hard to come by, you'll only need network access for a short period. So be prepared to string a long cable, or use a USB wireless-network adaptor.

No special tools are needed to build and install a Car PC. You can go with the favorite tools of professional installers, such as good wire strippers with spring action and wire-gauge sensing; a heavy-duty crimping tool; a thread-locker compound such as LocTite, which can prevent screws from coming loose from repeated vibration; and a collection of faston and other wire-splicing parts. Wire connectors are available in various assortments or in bubble packs from auto-supply stores, and they are highly recommended for a safe and professional-looking installation.

Here are the 14 steps for the Car PC assembly:

Here's a photograph showing how the components are placed for assembly onto the bottom plate of a VoomPC case. Note the overlapping strata of parts to retain our small footprint:

A Word about Car PC and Safety

Using a PC on the road requires a tremendous amount of responsibility. The purpose of having a car PC—in addition to being really cool, of course—is to add to the enjoyment and safety of the driving experience. Unfortunately, having something as wonderful and complex as a computer within sight and reach of a driver can present a serious distraction.

In other words, don't make your in-car PC a driving hazard for yourself or your clients. Instead, follow these important steps as part of your installation:

• Consult your local laws. In the U.S., for example, many states restrict the use of an in-car video monitor that's in the view of the driver.
• Take extra care to provide a safe installation. Design application access to be as easy and hands-free as possible.
• Consider having a serious talk with your clients about the safe use of the car PC. Since everyone will have questions and want to talk about their car PC, suggest an explanation before the trip gets underway. Or suggest offering to pull over to give a complete tour of the hardware and applications curbside, rather than while in motion.

Once the Car PC is built and installed, you'll be ready to load the applications your client desires. But be prepared for questions, lots of them. Car PCs get loads of attention from both potential clients and passers-by. Don't forget to mention to your potential clients that having a Car PC consolidates all their miscellaneous hardware and wires into one box with a large, easy-to-use touch screen. It also lets them run their favorite PC applications in their car. PC gamers will love it for the novelty. Salespeople will love the GPS and the integrated phone and PC applications. And all your on-the-road clients will enjoy the superior media ability of motoring in style with their car PC.

SIDEBAR: Additional Resources for Building Car PCs

Online Vendors: You'll want to source your parts from people who are familiar with the mini-ITX and know the car PC business. I found these three online vendors to be among the best:

• Mini-Box
• MP3Car
• Digital Worldwide

Discussion Forums: Check out the many car-PC sites forums for tips and tricks. Here are three I like:

• Car PC Specialist
• MP3Car.Com
• CarTFT

Books: I recommend two helpful books devoted to car PCs. These two books can be especially helpful if you don't have a lot of experience with 12-volt DC systems, are unfamiliar with "faston" connectors for splicing wire quickly, or are uncomfortable cutting into ignition wiring:

• Geek My Ride by Auri Rahimzadeh (Wiley, 2005)
• Car PC Hacks by Damien Stolarz (O'Reilly, 2005)

Additional ideas: Have a look at some pre-built car PCs. Streetdeck is one that has attracted a lot of attention.

General information on mini-ITX systems: Check out the EPIACenter.

ANDY MCDONOUGH is a professional musician, composer, voice actor, engineer, and educator happily freelancing in New Jersey.