[Update: This system is now complete and working. See details at http://noisymime.org/blog/2009/05/rallyduino-lives/]

So recently I’ve started playing slightly more seriously with my Arduino, I’ve even gone so far as having a plan on what the hell to do with it. For some time I’ve wanted to try my hand at putting together a homemade Rally computer and the Arduino seems to almost be the perfect platform for this (Though not without one or two shortcomings). For those not familiar with them, a rally computer in its most basic form is essentially just a glorified odometer, in other words, it measures the distance your car has gone. Very briefly the differences are:

  • Considerably more accurate
  • Can count up and down as well as being able to pause
  • Resetable, usually via a remote control
  • Usually also calculate average speed

If you want to lookup existing rally computers, I recommend you checkout manufacturer websites such as Brantz and Terratrip.

So why make your own when there’s already such good existing products? Well I can give you 3 reasons: price, openess and fun. All the units currently on the market are quite expensive ($500+) and are all very much proprietory, closed systems. My goal is to put something together than costs about $200 and is as open as possible.

Do demo what I’ve got going so far, checkout the video below:
YouTube Preview Image

So as you can see, the system is up and running with all the basic functionality. I need a few extra pieces of hardware (Case, power regulator and prototyping shield), before I give it a test in a real world scenario, but at the moment I’m confident things should work OK. The biggest problem I’m having at the moment is the responsiveness of the Wii nunchuck as a controller. It works OK in tests, but when you get the Arduino processing the input pulses (At around 150Hz) things start to slow down. Obviously priority is given in the following order:
Pulse Counting->Speed/Distances Calculations->Screen Updates->Nunchuck input

That’s about all for now. I’ll probably post about this again after I’ve done a real world test on a car so it will have to wait until the extra bits and pieces arive. The source code isn’t yet available (Simply because I don’t think there’d be much interest), but if anyone would like to see it, just leave a comment and let me know.

7 thoughts on “Rallyduino?”

  • […] T-1 days until our little bubs technical due date! No news yet though) I finally managed to get the rallyduino into the car over the weekend. It actually went in a couple of weeks ago, but had to come out again […]

  • I was also thinking it would be cool to do a rally computer with Arduino… I’m going to see if I have any LCDs I can hook up and may try snagging your code, see if I can get it to work.

  • Was also going to attempt a ‘Rallyduino’ sort of project. Do you mind answering how you configured the pulse input. (i.e. what did you use from our car to trigger the counter?, the VSS?)

    I have been trying to find info on directly hooking my Terratrip to the ABS Wheel speed sensors, as they have been disabled for stage rally competition anyway…

    • Hi Paul, almost certainly this is possible. I had someone contact me a little while ago saying that they had done just this with the rallyduino code. That said, it likely varies depending on the type of sensor. Really, all the system needs is a 5v square wave that represents a certain amount of distance. Eg: On a car with 4 wheel studs, each pulse represents 1/4 of the tire circumference in distance.
      If you can scope what the ABS sensor is outputting, send me an email and i’ll see if I can help in getting it working.

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