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Thread: Newbie Question: How to setup LCD in car?

  1. #1
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    Apr 2002
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    Newbie Question: How to setup LCD in car?

    Here's my specs so far:

    Compaq Deskpro 300mhz PII, 60gb of disk space, 64 mb RAM, Windows 95 running Winamp.
    Blaupunkt Casablanca with Aux-In enabled
    Cable runs from Line-Out on PC to Aux-In on head unit. Plays great. 29 second boot til I hear toons.

    OK, before I get flamed, I looked through all the pages in this sub, and didn't see my answer.

    Anyway, I've got the audio part of my Car MP3 player working. Now that this is done, the next phase of this project is to add video. Now here's where a ton of questions come in.

    I see lots of 5" to 7" LCDs available on PartsExpress.com, and other web sites. What is the easiest way to connect a color LCD display to my PC? I'm looking for a small one, that I can mount in between my visors. I just want to be able to see the desktop or the playlist so I can SEE what the hell the PC is doing, in case there is a crash, or just to pick songs from the list.

    I read all this talk about needing controllers and such. What do I need to connect the LCD from the PC? I'm assuming I need a video card that does TV-OUT? I have two open PCI slots in this PC, no AGP. I plan to use one of the PCI slots for a wireless NIC.

    Can someone get me started, or point me to some instructions. I'm sure someone, somewhere, has this documented on some webpage.

    Thanks.

    SirCyRo

  2. #2
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    I know this has actually been covered several times in a lot of different posts, so I will try to cover as much of it as possible, for all newbies. If anyone has further questions, I deal with interfacing computers and displays at work, so feel free to e-mail me.

    First, a brief history. NTSC TV signal principles were developed in the 1930s, and updated in the 1950s/60s to accomodate color signals. In the early days, the electronics could not handle the bandwidth necessary in order to draw the 525 lines we know today. The engineers used INTERLACING to solve this problem. Interlacing relies on persistence of perception, a phenomenon where our brains continue to see an image even after our eyes stop seeing it. Interlacing "draws" every other line (first odds, then evens), creating two fields which merge into one frame. All NTSC TVs are based on our 60Hz AC system, which results in 60 fields per second, or 30 frames per second. The electron guns used in early CRTs needed to have a 15.75kHz horizontal frequency (how fast the gun scanned left to right) in order to draw 30 frames per second.

    Early computers used digital connectors to interface to the video monitors, which were based on existing CRT/NTSC technology. Digital connections limited color resolution, so the engineers took a step back to analog. IBM developed the VGA system we are so familiar with today, introducing it in the mid 1980s. IBM engineers chose to use a progressive scan system for VGA, which resulted in the 31.5kHz horizontal frequency for standard VGA. Some standard frequencies include (all based on a 60Hz or Default refresh rate) 35kHz (800x600); 48kHz (1024x768); 64kHz (1280x1024).


    What does all this mean for Car PCs?

    1) The smaller the screen, the lower the resolution it is capable of. Also the more expensive they tend to be, especially for the VGA models vs. the NTSC models.

    2) LCD screens require controllers in order to "understand" the analog signal they are receiving. LCDs are digital devices (either on or off) and all of them need/have some sort of controller.

    2a) The type of controller determines the signal the computer needs to put out. NTSC LCDs have a controller which accepts either a composite or S-Video connection. These are less expensive because they do not need to meet the resolution requirements for VGA. VGA LCDs have a controller which accepts the VGA output from the video card. These monitors look better because there is a lot less processing going on in order to create the image.

    2b) Controllers are not interchangeable insofar as using an NTSC controller on a VGA LCD and vice versa.

    3) When using NTSC LCD monitors, desktop resolution should be set to 640x480, default refresh. This puts less work on the video card (when using an NTSC output) and the LCD.

    4)Use the best possible connection between the monitor and video card. If you are using a video card with TV out, and it has an S-Video connector, use it if the NTSC monitor has one as well. Again, less processing is taking place in order to create the image.

    5) If you can afford it, use a VGA LCD. If you are adventurous, you can buy a raw LCD screen, and track down a controller for it. If not, the Xenarcs look really cool. (Search for "Xenarc" to find the links). Another possibility is to use an old LCD Presentation Panel (there are usually a bunch on eBay). These were the devices presenters placed on overhead projectors back in the early day of PowerPoint presentations. (This is the option I am using as I was able to buy one really cheap from my company). You will need to create some sort of backlight and custom case.

    6) Changing the refresh rate changes the horizontal rate, which can affect compatibility. Set your refresh to default, you won't see any flicker on an LCD.

  3. #3
    Newbie
    Join Date
    Apr 2002
    Posts
    44

    thanks

    Thanks for the reply. That's a lot of help.

    The VGA LCD's you speak of, what kind of connector do they have. Do they hook up just like a standard desktop monitor would?

  4. #4
    Maximum Bitrate
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    Yep, the controller card should have a standard HD15 connector on it.

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