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Simulate OBD with FB??

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  • Simulate OBD with FB??

    Hi,

    A friend of mine called me yesterday with a challenge. He has an old VW Golf 1, in which he will place a new engine. This engines ECU will be removed, because he's going to use mechanics only, and some 12v for the ignition..

    He asked me to build hem 'something' with a small display from which he could read the values normally done by analogue dials. Values like Oil temp, Water Temp, Oil pres., Air intake temp and Speed.

    The problem that arises here is, there is no OBD.
    So I thought;
    1. is it possible to connect the FB to the original sensors of the car, and get show the info's on the CarpC as dials or digital meters?
    2. If I'm able to do so, would it be possible to lit up some leds if a value reaches a certain level.
    3. I'd like to atach a VFD display too to display the most simple values. This way the driver doesn't have to stare the the 7" display to see the exact values..

    I hope you're willing to help me, and give me some advice?

    Greetz Hakko

  • #2
    This has been attempted before (About 10 posts below yours)
    http://www.mp3car.com/vbulletin/fusi...s-project.html
    "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
    RevFE
    My Shop

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    • #3
      Yeah I saw that, but I don't understand what he is saying. I thought to open a new treath not to spoil his one with questions..

      He's talking about
      Original GM 0-90 ohm sensor. I'll connect a FB 5V out to a 51 ohm 1/4watt. The 51 ohm will be connected to the FB AIN then a 2.2 ohm and the signal wire from the fuel level sender. Should give me a 0.2V-3.2V reading

      Am I right thinking the FB only accepts 0.2v - 3.2v reading for every sensor connected?

      Comment


      • #4
        FB can read from 0-5v on the analog inputs. His reasoning behind that setup is likely due to how the fuel sensor is designed (what resistance ranges it has). That kind of a question however, should be asked in his thread, as he would know best.
        "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
        RevFE
        My Shop

        Comment


        • #5
          thanks for the feedback. Will proceed asking question in his threath then

          Comment


          • #6
            Brace yourself

            The Fusion Brain measures voltage up to 5V. Over 5 and you fry it. Many automotive sensors are resistive. As the pressure/temperature changes the resistance (ohms) varies. With another fixed resistor you can create a voltage divider and measure the changes of your sensor as a voltage. I use this simple calculator a lot:
            http://www.raltron.com/cust/tools/voltage_divider.asp

            In the example above of a 0 to 90 ohm sensor, I added two fixed resistors with the second connected to the sensor. There is an issue with current flow so that I have at least 2.2 ohms when the sensor is at 0. So in the calculator enter 5 for the input voltage. Enter 51 for R1, the first resistor. Enter 2.2 for R2, my second resistor + the sensor at 0. Hit compute. The Fusion Brain in a theoretical world will measure 0.207V between the pair of resistors.
            Replace R2 with 92.2(2.2 + 90 sensor max), clear the output voltage from the calculator and hit compute. You'll see the FB will now measure 3.219V.

            I've actually increased my R1's to 100 ohm resistors. There is a balance between using as much of the FB's 0-5V range against current flow and an error imparted by small resistors I don't understand. Now you just have to figure out the VW sensor values or switch to GM sensors.

            I have Speed, RPM, Oil pressure, Battery voltage, Fuel Level, Coolant Temp, Inside Temp, Outside Temp, Light, Turn Signals, High Beam, Check Engine, Brake Warning and Skip Shift all working along with various level warnings (low fuel, over heat ect.). Need some more hardware for fuel pressure, MAP, AFR. Can't do all that with OBD1 or 2.

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            • #7
              I don't know if it'd meet your specific needs, but I've poked at this before:
              OBDII and Fusion Brain

              Gary (-;
              OBDGPSLogger, for logging OBDII and/or GPS data
              OBDSim, an OBDII/ELM327 software simulator
              mp3car forums: obdgpslogger, obdsim

              Comment


              • #8
                More then 5.2V and you fry the FB so most of the time you aim for your voltage divider to have a range of 0 to ~4.5V so that you have a decent margin of safety but also a decent accuracy. Its also worth noting that some modern sensors (like temp sensors or knock sensors) may be capacitive so double check before your wire everything up.
                openMobile - An open source C# Front End (why choose openMobile?)
                - Always Recruiting Developers -
                Like what you see? Donations are always welcome

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                • #9
                  Originally posted by ACCLR8N View Post
                  The Fusion Brain measur... ...Can't do all that with OBD1 or 2.
                  Wow, thanks for the clear explaination! I think I understand completly now how to get started!



                  @chunkyks:

                  Am I right here; your OBD simulator will only work on linux right?


                  Hakko

                  Comment


                  • #10
                    My simulator runs on windows using com0com. I don't know dbus or fbd work on windows, though, so it's still possible that the way to achieve what you want is by writing a new generator that communicates with the fb via usb on windows

                    Gary (-;
                    OBDGPSLogger, for logging OBDII and/or GPS data
                    OBDSim, an OBDII/ELM327 software simulator
                    mp3car forums: obdgpslogger, obdsim

                    Comment


                    • #11
                      Real windows version discussed here: http://www.mp3car.com/vbulletin/engi...tor-redux.html

                      Gary (-;
                      OBDGPSLogger, for logging OBDII and/or GPS data
                      OBDSim, an OBDII/ELM327 software simulator
                      mp3car forums: obdgpslogger, obdsim

                      Comment

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