Hack26.Install a VGA Touchscreen in Your Dashboard

Hack 26. Install a VGA Touchscreen in Your Dashboard

Although it's a more challenging project, a cleanly integrated center console screen can provide you with a high-resolution touchscreen that's ideal for controlling your in-car PC.

Many of the newest cars come with a factory-installed navigation option. However, you are invariably stuck with the software that came with the car, and these navigation units usually can't play DVDs and certainly can't play video games. Also, after 5 years you'll find yourself with an old, clunky navigation unit, even though computers will have increased in speed by 10 times.

If you instead had a simple touchscreen that controlled whatever state-of-the-art computer you felt like installing in the trunk, you'd be ahead of the game. You'd be able to read sharper text and view clearer maps, because VGA screens run at higher resolutions than the RGB screens that come in cars. And you'd be able to continually add new programs and new features, while maintaining the clean look of a factory install.

There are several early manufacturers in this market, all of whom use similar screens with different enclosures and features. Xenarc (http://www.xenarc.com) and Lilliput (http://www.newision.com) are two such vendors, and Figure 3-7 shows some of their screens.

Whether you are replacing your existing screen or installing a new one, there are a number of planning steps to take before you make a purchase.

3.5.1. Maximizing the Screen Size

VGA touchscreens come in sizes ranging from 7" wide-screen monitors to 10" traditional 4:3 monitors, and all the way up to full-size LCDs. If you're replacing a factory screen, you want to get a screen as close to the original size and shape as possible, in order to both minimize the amount of customization you need to do and leave open the option of installing the original screen if you ever need to (e.g., when selling the car, returning it after the lease is up, or returning it to the friend you borrowed it from).

If you are doing a new installation in a vehicle that did not come with a touchscreen, you have a couple of options. First, if your vehicle was not originally designed to have a screen at all, you may have to fabricate a completely new dashboard panel. A good custom audio shop can create any shape you need, using fiberglass.

Figure 3-7. Two Newision Lilliput touchscreens

If you are going to have to build the screen-mounting frame from scratch, you do have the option to "go big" or "supersize" your screen. You may be able to squeeze a 10" or even 12" screen into your center dash paneljust be sure the laws in your state won't keep you off the road with your oversized video unit.

If your car has a factory navigation option but you didn't choose it, you have more options. You may be able to buy the navigation-ready dashboard framing from the dealer or, even better, from a car parts distributor (not a chainlook in the phone book for replacement parts for your particular car) or a salvage yard. If you can find a totaled version of your car with the navigation option installed, you may be able to get all the dashboard pieces you need, and if you say you don't want the screen the price may not be that bad.

3.5.2. Determining the Placement

Installing the screen involves more than simply finding an empty space in your dash and sticking the screen in it. Before you even purchase a screen, you should make a cardboard mock-up and place it where you anticipate installing it. Make sure that the driver and the passenger can reach it (if it is a touchscreen) and that any other controls it may be displacing can be reached in their new homes as well.

Many of the controls in a car are oversized by design, to take up more space on the dashboard. For instance, the temperature controls on many cars are simply three dials and two sliders, which could fit in a 1" by 4" panel if the knobs were smaller. Instead, they are put in a modular 2-DIN panel that dominates the dashboard and takes up more room than the radio. Often these can be moved to another part of the dashboard, or even into the glove compartment if there is not enough room on the dash.

The more planning and purchasing you do yourself before you go to the fiberglass masters, the cheaper your project will be and the faster it will be completed.

3.5.3. Adjusting the Angle

Most in-dash screens are not adjustable. Thus, it is imperative that you get the viewing angle right. While preinstalled screens in modern dashboards are presented at a nice viewing angle, older dashboards are straight up and down, and a naÏve flush installation will result in a screen that you have to slouch down to look at.

Even if you get the angle perfect for yourself, you should try to ensure that taller and shorter people, both passengers and drivers, can also see the screen. You may have to evaluate several screens, because different screens have different viewing angles, and the touchscreen layer on the screen decreases the brightness and affects this angle.

Some screens do have a few degrees of pivot in their mounting, so they can point more toward either the left or the right. However, some cars with center consoles that point toward the driver may make a center-mounted monitor useless for anyone but the driver. In short, "screen test" your setup (pun intended) before you commit to its final position.

3.5.4. Ensuring Brightness

If the screen is going to be used in an SUV with tinted windows all around, the amount of ambient light competing with the touchscreen should be minimal. If you are installing the screen in a convertible car, however, it's important to make sure that the display on the screen isn't completely washed out by sunlight.

Before installing any screen into the dash, you should verify its brightness qualities and behavior under different lighting conditions. Many of the screens preinstalled in cars, while low resolution, have been designed to deal with diverse lighting conditions, or use buttons on the side for user input and thus do not have the brightness reductions caused by touchscreen capabilities.

Fortunately, there is a high-bright option available for VGA touchscreens. Some vendors (such as http://www.karpc.com) will sell you a Xenarc touchscreen that they have modified with a reflective back panel. While this washes out the colors a bit, it reflects incoming light and makes the screen usable even in bright sunlight.

Unfortunately, no current LCD screen is readable in direct sunlight. The most practical solution today is to shield the LCD from sun with good (deep) placement within the dashboard. If you look at many factory NAV units, you will see that they have a large frame around the screen and that the screen is inset several inches. This helps to keep the screen "in the shade" and viewable.

Gamma Control is a program that adjusts your gamma, brightness, and contrast levels based on the time of day and sunrise/sunset times in your geographic location. This makes it unnecessary for you to adjust your screen's brightness as the day changes into night. This program is also fully integrated into the voice-recognition program NaviVoice [Hack #60] by the same author. You can find both of these programs at http://www.whipflash.com/vamr/.

3.5.5. Exposing Infrared Controls

Because these screens are VGA, they can autosync to standard PC resolutions, and even switch between VGA and several composite video inputs. They also have built-in brightness, contrast, and other settings. However, if the screens are cleanly installed, the buttons to adjust these settings may be hidden away in the dashboard.

Luckily, many of the in-car computer screens (such as the Xenarc and Lilliput models) come with an external remote control that has brightness and source controls on it. If you expose the infrared receiver during your installation (just leave a small hole over the IR receiver eye on the screen), you can keep a remote in the center console and use it when you need to adjust these settings.

3.5.6. Integrating Existing Navigation and Video Features

One difficulty in replacing the factory screen is that the factory features, such as navigation, are designed to work only with that screen. Furthermore, factory systems never give you something nice like a standard VGA or composite port to plug into. Most of them use a multi-wire video connection called RGB (red-green-blue), which sits between composite video (low quality) and VGA (high quality). This allows their navigation screens to be fairly crisp, but it will make it difficult to connect your navigation system to your new screen.

One option you have is to convert the NAV unit's RGB output down to composite and connect that to your replacement screen. This is a straightforward solution, but it gives you an unacceptably lower-quality image than the factory RGB. The other option is to convert the RGB up to VGA, but this requires relatively expensive hardware and the addition of yet another item: a VGA switcher to switch between the PC and the factory navigation. So, if you replace your factory screen, you pretty much have to give up the factory navigation systemwhich you may or may not want to do, depending on how much of an improvement the computer-based navigation system you're installing is. (An alternative to replacing the screen is to make your computer talk to the built-in factory RGB screen [Hack #32].)

If you have a DVD player in your car, factory or aftermarket, you probably want to be able to display its output on your front screen as well. Most VGA touchscreens for cars have two additional video inputs for items such as rearview cameras [Hack #33] and DVD players. Optionally, you can play DVDs on your car PC, which gives a higher resolution on the VGA screen.

3.5.7. Finishing the Installation

While the passengers can manually turn on their headrest screens, you expect a dashboard screen to automatically power on when the car is started. Some of the models automatically turn on whenever there is power, but others need to be turned on by pressing the power switch. If your screen doesn't turn on with the car, read "Power Your Car PC" [Hack #42] to learn how to fix it.

Once you have your screen installed, if your PC is in the trunk, you may need to get 3-meter VGA and USB extension cables for the touchscreen interface. You should also configure your car PC to match the native resolution (e.g., 800 x 480 or 800 x 600) of your VGA touchscreen. Although it will display other resolutions, such as 1024 x 768, the native resolution of an LCD display is usually the sharpest and clearest image. If your car computer cannot output the right resolution, there is aftermarket software for Windows that may help. Linux users running X11 can simply set the right resolution and refresh numbers in their X configuration filesif their video cards support it, it will work.

As always, check the functioning of the system at various points during the install to make sure that you're on the right track. Having to take everything apart at the end to fix one forgotten connector is a waste of your precious car PC hacking time.