[Noisebridge-discuss] Open Source Bicycle Computer...

[Jonathan Foote]

I'm pretty sure bike computers use Hall effect sensors to
(contactlessly) sense wheel revolutions.
They are cheap and very easy to interface with
microprocessors/arduinos. They have three wires: power, ground, and
output signal, which gives you a clean logic pulse when a magnet
(affixed to the wheel hub) is in proximity. It takes very little
power. Here's one I've used successfully at 2.8V:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MLX90248ESECT-ND

Similar sensors come in a TO-92 package if that's easier to work with.

Also consider interfacing with a GPS module, which are relatively
inexpensive and pretty simple to talk to over a serial line.


On Sat, Oct 17, 2009 at 9:28 PM, Glen Jarvis <glen at glenjarvis.com> wrote:
> My Shimano Ultegra ST-6501 right bicycle shifter broke. But, the part can't
> be found any more. It's replacement has only one button and won't interface
> with my flight-deck....and, this cascading part replacement goes on...
> making a simple part replacement, that should cost $200 or less, almost
> $1000.
> That's crazy. Of course, I imagine a good deal of this is 'good business' to
> keep selling parts. I've been thinking about this for a month now and keep
> thinking of an open source bicycle computer. After some noise bridge Monday
> night hardware hacking, I'm inspired. The problem seems so doable..
> I've done some Googling to see what has already been done. This German
> design seems the absolute coolest:
>
> http://www.obico.de/
>
> Although it's "open source", I didn't see any schematics, parts, etc online.
> I wrote to them to see if I could buy the hardware and/or a kit to assemble.
> But, if they don't answer, would any one else be interested in taking a stab
> at this?
>
> I'm a software developer by trade and took digital design courses in
> college. But, anything analog is beyond me (currently). I'd definitely need
> to collaborate with others...  Logically, it seems the first two hurdles to
> get past are:
>
> 1) to create something that fits on the bicycle that can send a pulse at
> every turn of the wheel, and
>
> 2) A dynamo/power/recharge system -- it seems silly not to convert the
> mechanical energy from a bicycle and use it.. Here's a similar idea:
>
> http://www.ktverkko.fi/~msmakela/electronics/dynamo5v/
>
> The obico also does this as well.
>
> I already have a pretty good idea how to do something useful with a
> microcontroller, small display, etc. But,  I'm *very* interested in
> the obico's hardware design and Linux port -- totally above and cooler than
> what I was thinking about.
>
> I was pleasantly surprised to find a site that has some roots at
> noisebridge. I found this fun little tangent from a manufacturer that did
> the boarduino kit we assembled in Monday night's circuit hacking..
>
> http://www.adafruit.com/index.php?main_page=index&cPath=6
>
> I found some old palm hacks and some other attempts at this:
>
> http://blogs.thehumanjourney.net/finds/entry/20080306
>
> http://japan.maxim-ic.com/appnotes.cfm?an_pk=3845
>
> Please say that someone here at noise bridge has crossed this bridge,
> already has a solution and/or is interested in making one (similar to
> obico's design). Again, I wrote to obico tonight, but their website hasn't
> had anything posted since 2008. Does anyone know them?
>
> Cheers,
>
> Glen
>
> _______________________________________________
> Noisebridge-discuss mailing list
> Noisebridge-discuss at lists.noisebridge.net
> https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
>
>