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I want to build a DIY OBD2 interface

Discussion in 'Electronic Design' started by powerampfreak, Jan 1, 2013.

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  1. Hello all.
    Happy new year to all of you out there !!

    Now to the serious stuff:
    I need to continously read out some of the OBD2 data available in my car. It's about long and short term fuel trim datas.
    Well, I know the ELM327 can be used, and use it as a OBD protocoll device.
    BUT - it would be even more elegant to use a custom PIC microcontroller already running a firmware which communicates over OBD through a interfacechip like MC33290 or so.
    I don't need to read out datas on a LCD, I just need the datas as input to my processing.
    Like this:
    1. I initiate a read of short-term fuel ratio.
    2. I get back a string of data from car ECU through OBD protocoll.

    Does anyone know of a DIY open source OBD protocoll PIC processor?

    Best regards
    The freak
  2. Guest

    If you value your time at all , go with a blue tooth ELM327. You can
    get one from China for about $12. Any DIY device is likely to be
    programmed for only one brand of car.

  3. Neon John

    Neon John Guest

    This isn't open source but it is a turn-key solution to your problem.

    This guy is a little bit nutty but has an encyclopedic knowledge of
    OBD. The software is free and fully functional except that it won't
    talk to an interface cable without the secret code. You can download
    the software and play with it with saved data. Which brings up the
    next item on your list. It will log whatever parameters you want
    logged indefinitely or until you run out of disk space.

    I have his universal interface cable (all three OBD-II protocols plus
    CANbus). The cable consists of the proper connectors and a little
    plastic box containing the PIC that translates bus data to serial
    data. You'll need a computer with either a serial port or a
    serial/USB cable.

    Lastly, if you're a Linux person, you'll be glad to know that it runs
    fine under Ubuntu Wine.

    John DeArmond
    Tellico Plains, Occupied TN
    See website for email address
  4. Den tisdagen den 1:e januari 2013 kl. 22:04:02 UTC+1 skrev powerampfreak:
    Thanks for all advice.
    Though I want it all to be a standalone device without the need for a PC.
    This is all part of a possible new productdevelopment.
    Maybe the ELM327 solution will be the most easy way to go, then all protocoll "stuff" is already taken care of. And all I have to do then is to build an RS232
    communication with my own PIC to read out and interprete the data.
  5. Chris

    Chris Guest
  6. Guest

    Try Ebay item 170923726521. Shipped from New Jersey , less than $20,
    and no assembly required.

  7. hamilton

    hamilton Guest

  8. Chris

    Chris Guest

    All depends how keen the OP is to DIY.

    He/she can still download the construction article & source the parts etc...

    The designer of the project may also still be contactable to get access
    to any microcontroller code required.

  9. Guest

  10. Guest

  11. hamilton

    hamilton Guest

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