FAQ: Why you can't use your headunit or GPS touchscreen to control your PC

Bugbyte · 12-27-2007, 02:53 PM

This question comes up over and over:

Can I use the touchscreen on my (AVIC, Headunit, GPS unit, dashboard LCD) to control my computer?

Short attention span answer: No.

Longer explanation

Sure, it looks like a good idea. Why can't I use the touchscreen on my GPS unit to control my computer? It has a video input I could see my computer screen on.

Or, your car came with a built in screen, say with nav on it or with system information on it like the Prius has. It has a touchscreen, why can't you use it to control your PC?

The answer is that you aren't thinking it through very carefully. The most common type of touch screen uses a 4 or 5 wire resistive coating that produces a particular voltage when you touch it. There is a controller that measures this voltage and relays the information to a control device -usually a hardware based computer that interprets that information and processes accordingly.

What that means is the touch screen is already in use by another computer -either your GPS unit or your car's computer system. In order for you to use it to control your PC, you are going to have to figure out a way to either switch the touchscreen connection or share it between your PC and the other computer.

You'll have to open up the unit with the touchscreen - the GPS or the car nav system or the headunit, hack into the wires on the system, then connect those wires to your PC. Will it work? Maybe. Or maybe not. Or maybe you'll fry your headunit/GPS/car nav system. Or the PC. Or both.

Is it impossible? No. It CAN be done. This guy did. But if you don't understand why you can't share the touch screen in the first place, you don't have the have the necessary skills to do so.

MatrixPC · 12-27-2007, 03:11 PM

Another guy did it with the Honda/Acura Nav system on the TL.
http://www.mp3car.com/vbulletin/show...tegration.html

Bugbyte · 12-28-2007, 12:32 PM

This is probably also a good place to point out that the screens that come with your car or your HU are video, not VGA screens and are much lower resolution than VGA. The link above includes a number of pictures of the computer on a video screen.

Take a look at the desktop below. Note how little space there is between the Start menu and the taskbar icons on the right. There is only enough room to display two running applications. Note also how few icons are on the desktop and the fuzziness around the text. The reason for this is that the display settings have been cranked way down to something on the order of 640 X 480 or less.

This is necessary because the video standard is nowhere near as crisp and clean as a VGA screen. That means two things - you display less and what gets displayed doesn't look clean. With exactly the right skin and colors, you can make it work, but just recognize that it is a compromise.

Note in this image how much screen real estate the Google page takes up. Almost the entire vertical and horizontal space. Note also that the text appears fuzzy. As a comparison, load Google on your VGA computer screen and shrink the window down until it is roughly the same appearance of this image. That's how much space you'll get on your car PC desktop if you use a video screen.

Linton · 01-15-2008, 02:20 AM

I thank you all for your valuable feedback. I will search for a double din unit that will support VGA and USB.Hopefully someone can lead me in the right direction.

Linton.

2k1Toaster · 01-15-2008, 02:39 AM

Quote: Originally Posted by Linton

I thank you all for your valuable feedback. I will search for a double din unit that will support VGA and USB.Hopefully someone can lead me in the right direction.

Linton.

http://www.digitalww.com/store/prodd...p?prod=DWW6500

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