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Analog to Digital Conversion

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  • Analog to Digital Conversion

    Its been a long time since I have posted on here.. but my interest has recently been renewed.

    I'm building a truck from the ground up. And I'm adding some vehicle sensors (diff heat sensor, boost sensor, egt sensor, etc).

    Does anyone know of a manufacturer that makes a unit that will take the analog resistance and convert it to a digital format.. like a serial connection, or USB?

    The idea is to mount an lcd that will show me 8 or more sensor outputs...

    These will not be read through OBDII


  • #2
    Game port/joystick port?
    (with a multiplexer to get the 8 inputs).
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.


    • #3
      I have heard those are very inaccurate. I'm going to be dealing with the in-accuracy of the sensor, and vehicle wiring.. would rather not have something that needs to be recalibrated all the time.

      Good idea on the multiplexer.... I didn't think of that.



      • #4
        National Instruments has a catalog full of instrumentation, sensor, sensor interfaces, and data collection devices and software. Their stuff is applicable for a small garage lab all the way up to a larg-scale fully automated factory or commercial manufacturing/test facility. If they don't make it, it probably doesn't exist.
        2004 4runner


        • #5
          Go for this one:

          PC Data Acquisition Unit (CPS93)

          It has:
          Eight Digital Outputs. Open collector, 500mA, 33V max.
          Sixteen Digital Inputs. 20V max. Protection 1K in series, 5.1V zener to ground.
          Eleven Analog Inputs. 0-5V, 10 bit (5mV/step.)
          One Analog Output. 0.2.5V or 0-10V. 8 bit (20mV/step.)

          I have used amazon electronics, and their kits are great.


          • #6

            Thanks for the suggestion. Do you know where I might find their catalog.. online or otherwise?

            NewTechFool..... wonderful source.. Thats basically what I want to do... now I just have to figure out a way to avoid using a parrallel port (ick!) and get the volts from 12V to 5V (vehicle is 12 Volts which I would like to use to power these circuits). You have definatly got me going in the right direction though.

            I was thinking about this a little more... and ultimatly this is what I would like to do.. maybe someone has done it before?

            Replace some of the in-dash gauges with an LCD screen. Have this LCD screen report on any non-critical guages (Speedo, RPM, and Fuel will probably stay original.. because I REALLY need those). That leaves coolant temp, oil pressure, voltage, boost, exhaust gas temp, diff temp, wheel hub temp (4 hubs to monitor), transfer case temp, wheel air pressure (front and rear), and outside and inside atmospheric temp. So thats 15 inputs.. maybe 17 if I figure out a good way to control the adjustable shocks (those are actuated by air pressure.. so a sensor and couple relays might work well).

            Of course the must have backup camera, and gps is required.

            So.. I have seen some kick *** installs, and some amazing hardware developed by people on this board.. has anyone attempted this big of a project and actually made some progress? This is a multi-year project thats also dependant on actually getting the truck built as well.



            • #7
              Any decent microcontroller has analog to digital conversion.


              • #8
                Some PIC MCU have them.



                Just look around


                • #9
                  Actually.. some one just posted this in another thread....


                  Anyone know anything about these? Seem to be exactly what I need. The interface kit has 8 digital inputs (would read if a switch was on or off, right?), 8 digital outputs (power relays or led's, right?) and 8 analog inputs (read sensors).. and its usb, and has open source drivers.

                  This seems to be the way to go.. unless anybody has better suggestions????



                  • #10
                    try to make one your self.
                    a picaxe 18A would probly be good.
           there just a pic chip that is realy easy to program.


                    • #11
                      This one is very popular
                      2004 Subaru STI
                      AMS CG65 2.4Ghz P4 w/512MB DDR, 40GB HD
                      Audigy2 ZS, Xenarc 700TSV, Gyration Media Center
                      WinXP Pro, ME 2.1, AudioBahn 5100T Amp
                      AWT10X Sub, JL XR100-CT tweeters
                      Sony XPlod fronts, Kenwood Excelon rears


                      • #12
                        STIdev beat me to it with the labjack post. I've been considering one of those for some similar instrumentation for EGT, boost, and battery monitoring.

                        Haven't done an investigation into pressure, etc, but for thermocouples to measure exhaust gas temp, if you can do a bit of electronics work, it looks like the Analog Devices AD595 may be a way to convert a thermocouple to a voltage that something like the labjack can read.

                        For what its worth, I'm thinking about some Hall Effect current sensors like these for monitoring the charging system.

                        For dc/dc converters to give you something other than automtive "12VDC" places like Mouser and Digi-Key have lots of those of various kinds. Keep in mind that vehicle 12V is more like 8 to 14.4 or something like that and can be really noisy which can cause assorted problems if you're trying to measure things. e.g. If you have a temp sensor that acts like a resistor in a voltage divider feeding the analog/digital converter from a source that varies by +/-20% or more, (with noise spikes even worse) thats really going to throw your accuracy off.