Thread: GPS System - Dashmount 7" touchscreen

Thought I'd share my GPS setup in my D2.

Here's the list of components-

Hardware-

• Garmin GPSMAP 76S
• MPC-425 fanless computer (12VDC, Celeron M 1.5GHz, 512 MB RAM, 40 GB HDD)
• CarNetix CNX-P1290 Dual Output 90 Watt 12V DC-DC Regulator
  Xenarc 7" Touch Screen
• External GPS Antenna

Software-

• Windows XP
• GarminCity Navigator
• Garmin Metroguide
• OziExplorer
• RAVE

The 7" touch screen is mounted on top of the dash. I've found if you pull out the radio, bolts can be inserted up through the vent from below to allow bolting of the screen. The supplied screen mounting bracked is screwed to a piece of flat MDF which is then bolted using the "through vent" bolts and suitable flat washers. This means I don't have to drill any holes anywhere and the whole thing can be removed leaving no trace. The radio goes back in of course. When parked in the sun I always use a silver windscreen shade to prevent excessive heat build up in the LCD screen. It's been there for a few years now.

The screen has 1 VGA input (for computer video) and 2 composite video inputs that may at a later date be connected to a reversing camera or DVD etc. if I wish. It also has a USB cable which attaches to the computer to allow the touch screen to work. It is powered directly from the vehicles nominal 12VDC. Note that this scrren has proper VGA input. Many of the cheap screens don't have this and are really only good for watching TV, camera video or DVDs etc.

I'm in the process of building a fibreglass cover for the screen. Currently it has a cardboard mockup over the top. The finished product will have a USB outlet in it as well to allow contection of USB memory sticks, camera or whatever else.

The GPS is mounted on a RAM Mount holder next to the gear stick. This is part of a legacy install from before the computer and screen. I usually have a silver cover over the top. This keeps the hot sun off and minimises prying eyes a little. I leave it powered up all the time. I've had an older GPS damaged by the sun getting to the screen and causing a large black mark to slowly creep over one corner of the LCD screen. The GPS is connected to the computer by a serial interface.

I found GPS reception significantly improved by using an external antenna mounted at the rear of the vehicle on the spare wheel mount. The antenna cable is nice and thin and can be run around the door (hinge side) and behind the pockets in the cargo area of the Discovery then under the carpet and door sills. It pops out just at the rear of the drivers seat and then on to the GPS. The antenna was only available in white at the time. I spray painted it matt black.

The computer is a fanless model located under the passengers seat. A mounting plate was made with two strips of 90 deg angle aluminum bolted to it. This plate was bolted to existing floor studs under the seat. The aluminum forms two parallel rails for the computer to rest on. Each rail slots between the case heatsink ridges and holds everything tight. The power supply sits on top and the whole lot is held down with some elastic straps. Been perfect for 18 months it been there.

The computer runs Windows XP SP2 and has been very stable. The CPU is a low power Celeron M 1.5 GHz. 512MB RAM seems to be ample. 40GB HDD has been ample so far as well. There are no fans inside the computer which improves reliability. The CPU is pressed against the case which asts as a giant heatsink. Only moving part is the 2.5" laptop style HDD. I keep image backups of the HDD. I guess on a long trip I could carry a spare and restore the image.

The computer requires a regulated 12VDC to work. Vehicle power is not really suitable, so a DC-DC regulator is employed. It’s connected to an unused plug under the seat which has a constant 12V (nominal) from the battery on it. I guess it’s for electric seats or seat heater or some such thing. There’s a 40 Amp fuse supplying power and a thick (purple) wire so it can take a fair bit. More than my setup needs anyway.

The DC-DC regulator also acts as a startup/shutdown controller for the computer. I have a small switch currently in a jiffy box tucked up near the Hi/Lo range selector. It signals the DC-DC regulator whether you want to start or shut down the PC. It has some added smarts to time the shutdown and kill power if the PC has not shutdown in a reasonable timeframe. Also has low voltage detection.

Around town I run Garmin nRoute with City Navigator maps. This allows turn by turn navigation and works quite well. Has a few hiccups every now and again but it seems most software has its own quirks.

Out of town I can switch to Ozexplorer and whatever topo maps I’ve got for the area I’m in.

Most interaction with the system is by the touch screen and stylus. However I have a small PS/2 keyboard plugged in and sitting just behind the front seats. This allows entering street addresses etc in.

The screen brightness can be adjusted from the screen’s front panel. At night I turn the brightness/backlight right down so it’s not distracting. With it dimmed down it becomes a faint glow. If I’m using nRoute I don’t really look at the screen anyway as it gives spoken directions.

Here are some pics-


(above) Dashboard with screen running Garmin nRoute and GPSMap 76s






(above) Windows XP with custom wallpaper. Amazing how many people think it's a factory install....






(above) Front view of MPC-425 computer. I didn't get the CD-ROM drive. All connections at rear.



(above) 12V DC-DC regulator with cover off.


(above) External antenna over spare wheel.

If anyone has any questions I'd be happy to answer them.

Hmm, very nice!

It's giving me ideas. I've an old 233MHz Pentium laptop that doesn't have a working screen (OK on external monitor).

How expensive are the 7" VGA touch screens?

Ron