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I2C in an automotive environment

Discussion in 'Misc Electronics' started by Amos K, Dec 31, 2003.

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  1. Amos K

    Amos K Guest

    I'm starting a system design for my car that will need an interface
    between each subsystem (alarm and locks, engine control, windows and
    lights, stereo, displays ect...) I chose I2C over RS-485 because it is
    widely accepted and easy to impliment with minimal parts. Has anyone
    tried using it in an automotive environment? I'm concerned there might be
    to much interference causing data transmittion problems.

    Is there maybe a better thread for this question someone knows about?

    Thanks for any input

    -Amos
     
  2. I2C is widely accepted and eeasy to implement with minimal parts.
    The traditional I2C is not useful outside the box for anything
    that needs reliabity, because it is quite sensitive to interference
    (unbalanced bus with open collector drivers and weak pull-up) and
    the communication protocol/ICs does not have any useful built-in error
    detection/correction.

    I have heard somebody mention I2C over RS-485.
    I have not heard much of it or seen it used anywhere, so I doubt
    that it woudl be widely accepted.
    I have not tried to use it in automotive enviroment.
    I have used I2C on some other things...
     
  3. Amos K

    Amos K Guest

    I was worried someone would say that. I've thought about using shielded
    cable. Triax most likely, if I can find some. Think that would help
    enough?

    I've not heard of I2C over RS-485. I'll do some research but it seems to
    me that it makes more sence to do straight 485. If I had a I2C sensor I
    wanted to hook up it might be worth looking into. Then again it would
    probably be easier and cheaper just to hook the sensor to a micro and put
    that on the 485 drop.

    Thanks for your input.
     
  4. Can't sya for sure if triax would be gopod enough.
    I2C in car environement sound very unrelible to me.
    Here are some lins for I2C-RS485 adapter plans I have found:

    I2C - RS-485 adapter
    http://vodka.tky.hut.fi/~jap/Electronics/I2C-adapter/

    I2C Serial Port Adapter & Extender
    http://zebra.tky.hut.fi/~jap/Electronics/I2C/SerialAdapter/
    Using I2C only on very short local communications between
    the sensor and microcontrolelr, then the micrcontroller
    communicates through RS-485 sounds the most sensible solution.
    It coudl be a good idea to add some checksum etc. to the
    communcation packets to make sure that data gets through
    right and errors are detected when they occur.
     
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