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Thread: Another E46 carputer

  1. #1
    Newbie aidilj's Avatar
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    Another E46 carputer

    Hi guys, this is my carputer installation. The installation is pretty straightforward and doesn't involve bondo or paintwork, just some sawing and epoxy. It is mostly done and there's no active development for months, but as usual there are always space for improvement. Enjoy!

    This is my first post on this forum, hope I'm not breaking any rules..



    Specifications
    Processor : Intel Atom processor D410
    Number of cores : 1
    Clock Speed : 1.66GHz
    Memory : 2GB DDR2 SDRAM 800MHz
    Graphic : Onboard - Intel integrated GMA 3150
    Sound : Onboard
    Hard disk : Seagate 5400 60GB

    1 Construction

    1.1 CPU Power supply

    Powering the CPU motherboard is M3-ATX. In picture below, M3-ATX is on the left while on the right is PicoPSU-80.



    1.2 CPU

    The Intel D410PT has the single core Atom processor soldered and passively cooled, onboard graphic with VGA out, 10/100 LAN, sound, 8 USB, SATA for hard disk and serial headers.



    Case is M350




    1.3 Monitor

    The monitor comes off eBay from China. It has two composite inputs and a VGA and reverse camera trigger. Unsurprisingly, during disassembly I found out that most of the monitor components are held together by hot glue..



    1.4 Amplifier

    Driving the speakers is a home made amplifier with TDA7560 quad 4x45W bridge amplifier. It is built so to use the remote wire feature from the power supply. Some construction pictures.













    1.4.1 Ground loop problem

    There was a lot of CPU and hard disk noise in the first revision of the amplifier. Turns out the problem is ground loop between the computer and the amplifier. Combating this, the loop was broken by separating power and signal noise with a 10ohm resistor.

    Quote from http://ludens.cl/Electron/audioamps/ta8215.html
    If you compare this schematic to the one in Toshiba's data sheet, you will notice that it's almost an exact copy, except for R3! Toshiba ties the input ground directly to the output ground. In a PC, this leads to trouble! A computer is a noisy machine. There are quite strong noise currents circulating through ground, for example. If you tie all grounds together, it could well happen that a noisy power ground return from the hard disk takes a route through this power amplifier and the sound card! This makes some nasty noise show up in the speakers.

    It's important to understand that the TA8215, like many such chips, has the preamplifier internally separated from the power amplifier. This is very useful to get rid of the described ground loop problems! I left the input ground separated from the output ground, except for the 10 Ohm resistor. If you happen to use this amplifier with a signal source that has a floating ground, the resistor is low enough to apply proper power ground to the preamplifier stages, and it works well. But if you install the amplifier in a PC, the 10 Ohm resistor is high enough to break up the ground loop that would otherwise form! All sensitive input points, such as voltage divider grounds, feedback returns, and ripple filter capacitor ground, are directly connected to the soundcard ground, and separated by the resistor from the power ground. The result is a very good rejection of noise. In my system, I can't hear power supply noise at all, but if I short out the resistor, the noise is all over the place!
    1.5 IBUS interface

    IBUS interface was built with the KBUS tranceiver IC (Melexis's TH3122) bought from reslers.de. It is the serial/rs232 version of it. A minor correction was made to Rolf's schematic on the max232 portion. Also the NTSC wire was omitted.

    Rolf's schematic


    from Maxim's datasheet


    Construction pix











    Navcoder showing whats happening on the IBUS


    1.6 Wiring harness

    For this, the 17 pin to ISO radio connector was bought for cleaner install. Wiring harness include a 22000uf 25V cap and 10A fuse. The wires are all salvaged from broken ATX power supplies.







    1.7 Bezel

    The bezel is from Janus. It is actually designed for double din radio so a little modification/hack is expected. I chose this over the TFT bezel because this is cheaper. The LCD is held onto the frame with epoxy.









    1.8 Software

    The computer runs on Windows XP PRO SP2, there are two frontends that I'm currently evaluating, Centrafuse and Riderunner.

    Windows installation through USB thumbdrive


    Desktop


    Centrafuse


    Riderunner with Simplistique V0.3 skin


    1.9 Putting it all together

    Mock up


    Cramming all in, amplifier sits behind the screen while the CPU will be in the glovebox




    CPU was moved to underneath the glovebox later

  2. #2
    Newbie aidilj's Avatar
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    1.10 Satnav




    Putting in the GPS receiver dongle, Instrument cluster off


    GPS receiver behind instrument cluster


    Garmin Nuvi 205w and Garmin Mobile PC side by side.


    1.11 Glare
    After a quick demo to officemates they commented that the glare is too much. An idea from a friend is to tilt the screen to not reflect directly from any window. So the screen was tilt down to reflect the rear seat instead of rear window. Visibility increase tremendously. Current orientation.



    Then an anti-glare screen protector for Galaxy tab was acquired


    I donít really like the result but Iím using it till now. Check out the pictures below.

    Factory screen protector


    No screen protector


    With "anti-glare" screen protector


    1.12 Reverse camera




    Wiring


    Schematic


    Override switch


    The camera


    In action


    1.13 OBD
    ELM 327 (version 1.3a) interface built and tested


    Schematic


    Some screenshot of the ELM 327 in centrafuse - taken with cameraphone

    Page 1


    Page 2


    1.14 Subwoofer
    I donít have a picture of it installed, but here it is before installation


    2 Still to do
    2.1 Get bluetooth USB dongle for phone
    2.2 Find and install mic for phone integration
    2.3 Reset button

    Cheers
    Aidil

  3. #3
    Constant Bitrate
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    Nice build!


    The display looks the same as the VM70. Would you mind providing a link to the Chinese reseller?

  4. #4
    Newbie aidilj's Avatar
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    Hey thanks sall

    Here's the item on eBay, see if the link works. The price has been reduced from last time
    http://cgi.ebay.com/7-VGA-AV-Touch-S...#ht_9259wt_989

    Cheers

  5. #5
    Newbie
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    Hey aidilj,
    Thank you sooo much for this posting!!!
    I was waiting for such a Manual/How-to for about 8 Months...
    I have pretty much exactly the same project: "E46 Carputer"
    - PSU (M3-ATX),
    - Janus Frame and
    - 7inch Touchmonitor (also madi in china, I think
    But I have bought the ASUS E35M1-I Deluxe Mainboard because of the power efficiency...

    I can use your picture #23 very good (E46-ISO Cable connection)
    because I was thinking about using the OEM speakers too for the beginning.

    My whole system is not yet tested because I'm a bit afraid to damage something, but in the next weeks it will get started
    - wish me luck - and thanks again - Buntline

  6. #6
    Newbie aidilj's Avatar
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    Hey Buntline, thanks. This is my first carputer attempt and I'm pretty happy with it.

    The Asus motherboard looks good, it is not available yet late last year (2010). This is a good upgrade candidate..

    Good luck on your project and let us know how it goes..

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