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Make a Speedo/Tacho for Motorcycle

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  • Make a Speedo/Tacho for Motorcycle

    If we already have a 'pulse' mechanism from the front wheel of the motorcycle are we able to create a 'large font' speedometer, switchable to a tachometer, using the OLED and 4DGL?
    (obviously needs a vibration-proof/waterproof housing I'll make after testing)
    I look forward to your reply. Regards, ActiveDave (Sydney, Australia)

  • #2


    ActiveDave,

    How many pulses per second do you think the wheel sensor will produce?
    Are the pulses fixed width, i.e. the count of pulses increases with speed, or does the width of the pulse vary with speed?
    There isn't a capture/compare type unit on the displays, but you should be able to code something in software.
    Which display are you thinking of using?

    There was a post a while ago with a similar type of project:
    http://www.websitetoolbox.com/tool/post/4d/vpost?id=2767589&highlight=bargraph

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    • #3


      I have a similar project in the works. (Slow progress at best.) In my case I am using a Gumstix Linux system to control three uOLED displays.

      If your graphics aren't too demanding I suppose you could do it entirely within the display but I am shooting for a lot more functionality so I went for the full blown system.

      By the way: I haven't addressed reading the tach and RPM pulses yet so I can't directly help you with that one. :^(

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      • #4


        The easy way for doing this:

        connect a ADC to the µOled (I2C or one-wire)
        use a LM2907 to change the RPM pulses to a voltage
        use a second LM2907 to change the speedpulses to a voltage
        messure those two voltages to get your speed and tacho.
        µLCD-70DT & Arduino DUE

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        • #5


          Yes that's a good solution, here is an app note / data sheet to get you started http://www.national.com/mpf/LM/LM2917.html
          Regards,
          Dave

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          • #6


            That is some good information, thanks. Now I just need to figure out how to get that into the Gumstix and I'll be doing good.

            I had been worried about trying to count the pulses and keep track of everything. Instead it is just a simple check of the voltage as needed. Calibrating the odometer should be fun.

            So who do I petition to get more hours in the day? ;^)

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