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Thread: fwaggles 1985 chevrolet suburban - 10%

  1. #1
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    Oct 2006
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    25

    fwaggles 1985 chevrolet suburban - 10%

    It's been a long haul, but my ghetto carpc is actually coming together!

    The first design criterion for this setup was to spend as little money as possible. My car has a lot of other **** that it needs before a PC in it, but I was willing to spend a few bucks here and there, but in general I wanted to use what I had laying around.

    So what I started with was an old Compaq Armada 7800 laptop. For those unfamiliar with these, there's not a lot of grunt there - 433mhz, 32mb ram. This particular unit had been abused, so I had to spend a couple weeks making it so that the screen didn't go pure white every few minutes. With that problem out of the way, I moved on to how to power it. These particular machines have a PSU built into the back of them, which overheats terribly. I really didn't want to go the DC-AC-DC method, so I started tinkering with the PSU to see what I could learn. It pushes out 14VDC and 5VDC, and one of the wires is used for the LCD on/off which I reserved this information for later.

    After testing, it seemed the laptop battery was charged purely from the 14VDC so I decided to see if the laptop would function without 5VDC from the PSU if it had a decent battery. It didn't. With some more playing around, I came upon the idea of pushing 12VDC from the battery, and using a small 4VDC power supply I had to push the 5VDC, but that resulted in me blowing some tiny little micro fuse on the motherboard. I decided to quit while I was ahead, I will probably just replace the PSU with a DC-DC convertor at a later date, something that I can use if this machine dies and/or I replace it with something beefier.

    With that out of the way and a stable machine running, I felt it was time to move on to the interface. For the primary display, I am using the laptop's LCD - I will mount it in a custom bracket at a later date. I dug out the old EloTouch CRT Touchscreen I had kicking around the closet, and took it apart. The pictures below show the process of peeling the touchpanel from the front of the CRT and mounting it over the LCD.




    The downside to this "ghetto" approach is that the panel is curved and the LCD is flat. In the middle of the screen, there's about 3/4" between the LCD and the panel, so if you're sitting to the left or the right the calibration goes out the window. I reason that this is only a temporary setup, and I plan on working around this with big buttons.

    The picture below shows the working touch panel. The controller runs from 5VDC, so I powered it from the USB of the laptop.



    So now I have a few more obstacles to overcome:

    • Power, probably I'll just buy an m2-atx or whatever (recommendations are welcome).
    • Change the OS. I planned on using FreeBSD for the backend, but I'm having problems getting the ELO Touchpanel to play nice under Xorg on it. I'll screw around with this some more later (I'm probably going to have to rewrite the driver).
    • Fabricating the mounting hardware.


    I've been visiting this site for about two years now, this is my first attempt at trying anything practical though. I've gotta say, there's a ton of great ideas here, and so far I'm really enjoying this hobby!

  2. #2
    Newbie
    Join Date
    Oct 2006
    Posts
    25
    getting freebsd to place nice with the touch panel was easier said than done, so i decided to give linux a go. surprisingly, it works out pretty good - performance is way better than i could expect from the same machine with a windows OS. of course the lack of decent GPS software is a little bothersome, but i might be able to work something out.

    installing mplayer took some effort (i'm spoiled with freebsd's ports), but it works after a couple days' tinkering:

    DVD Playback, windowed:


    MPEG playback, fullscreen:


    dvd playback is a little choppy (i'm using -framedrop in mplayer) due to lack of RAM, hopefully i'll track down those ram modules someplace, or maybe i'll buy some.

    still on the list of things to do is a front end, the power issue, and fabricating the dash modifications. i plan on giving a crack at the front end in the coming days.

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