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Thread: serial i/o board for vehicle sensors and multiple relays

  1. #1
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    Kind of wierd my thread did not post....anyway

    I'm thinking of designing up a serial i/o board that can be run of off a cars 12V unregulated power supply. I'm thinking of making the board so it can drive 6 or more off board relays as well as interface with vehicle temperature, pressure, and speed type sensors.

    I'd be open to any ideas people may have for different features for this type of I/O board.

  2. #2
    Constant Bitrate
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    megasquirt

    go look it up.

  3. #3
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    I may look into doing an ECU replacement like the MegaSquirt at some point. The idea behind this circuit board would be the ability to control relays and monitor and display different sensors on a car pc.

    For example the circuit board could be programmed to lock the car doors when you get to a certain speed...etc..etc...

  4. #4
    It ain't easy being a green moderator meddler's Avatar
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    there are a few good kits floating around. the Velleman k8055 (I think that is the model number) which is a I/O board and I am sure there are a few people that have done their own versions of what you want but not to the degree you want.
    Using one of these kit in conjunction with the outputs of the ECU (OBDII) to give you speed, etc should do what you want.
    don't forget you could always get vehicle speed from GPS
    Never let the truth get in the way of a good story

  5. #5
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    Thanks for the suggestions, I have thought of combining some of the products already on the market, but decided it would be easier and more compact just to design my own board.

    The problem I see with the Phidget style controllers is they seem to be designed for robotics and don't have the filtering needed on the power supply for a noisy automotive environment. With all that said here is my current thoughts on inputs and outputs for the circuit board:

    6 outputs designed for relays
    1 speed sensor input
    4 analog or digital inputs 0-5v
    4 analog or digital inputs 0-12v
    1 rs232 serial connection

    Can anyone think of anything else that may be useful that I am forgetting?

  6. #6
    It ain't easy being a green moderator meddler's Avatar
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    If you plan to release / sell the circuit, possiblly make it usb for ease of connection.
    Never let the truth get in the way of a good story

  7. #7
    Variable Bitrate
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    I have made my own version, but for the first time just the monitoring one.

    It is a PIC18F4525-based PCB, that is able to receive
    - speed sensor signal
    - rpm sensor signal
    - 11 12bits analogous channels in the range of 0-5V (in case of higher voltage, you need to reduce it by resistors and a use of a zener diode. (akku voltage and in-out temp resistors, eg.)
    - 8 digital input in the range of 0/12V (e.g. I use it for the rear camera) it can be chained by cheap, 8 bits parallel-serial IC units.
    It is connected to the PC via printer port

    I personaly do not prefer USB, because the communication protocol is too difficult to me, and I have no documentation how to handle USB on both end (under MASM32 assembly or usbPIC register-leveled setup).
    It is the only reason, why I do not use USB. More reliable, noise-tolerant, simplier. If only I had an example...

    Besides - in this case - there is no need for high-speed data transfer.
    By means of parallel, one can reach as high as 45Kbytes/sec, that is more than enough for any appcication that monitors and displays any part of the car. In my system I use 0.5 Hz displaying rate.

    The total cost was under 30 $

  8. #8
    FLAC sama's Avatar
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    u could always get a usb printer port

  9. #9
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    serial i/o

    I definatly am interested in this board. Could you sell this to me? do you have a software to be able to read the inputs? Could you link this with LABView??

  10. #10
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