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Old 08-21-08, 02:34 PM   #1
Rubin110
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Looking for a odometer / speedometer that can interface with a PC live

Hi there. A friend and I have a project in planning which requires a odometer or speedometer that can interface with a PC and send it live information. Basically I want it to feed the speed or distance ridden to a computer as it's happening. The laptop or electronic device that will be picking up this information will either be on the bike (in a pannier I'm thinking) or on the riders back in a bag. GPS is out of the question as this bike may go onto some sort of public transportation, and we need distance ridden by human power. Also if this does is serial based, that would be best, though we can sort of deal with USB.

Hopefully someone here has something in mind that might fit this bill. Thanks!

Last edited by Rubin110; 08-21-08 at 04:41 PM.
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Old 08-21-08, 04:42 PM   #2
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Sounds like you just need a programmer, or maybe you already have one. All a cycle computer does is simple calculations based on the magnet+sensor, signal pulses combined with the wheel/tire diameter. The magnet just closes a simple circuit inside the sensor and every time that happens the computer records it as one wheel revolution. Seems like figuring a way to just receive the pulses and doing a bit of programming would be way cheaper than trying to interface an expensive cycle computer with a PC. Any cycle computer that interfaces with a PC is gonna cost ya.

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Old 08-21-08, 04:55 PM   #3
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+1 on eliminating the middlecomputer.

If GPS is in the budget, maybe you could do all you want with a GPS device hooked to the computer.
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Old 08-21-08, 06:59 PM   #4
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Do you really need the data going to the computer as the bike is ridden? If you can wait until after the ride to download the data, then you could easily use a Polar 720i or 725i, which will log speed data up to once every 5s internally and be downloaded to a PC afterward. From there, you can do whatever you want with the data.
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Old 08-21-08, 10:06 PM   #5
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+1 on the GPS

I'm a programmer, and have thought about this kind of thing myself. Realistically though, using a computer to collect the data won't offer any benefits since you can't use it while riding. You get the extra weight and complexity of something designed for general purpose computing, and the only data you could collect is speed at different time intervals.

A GPS is smaller, has better battery life, is easier to use (you don't have to boot it up, or hope that the shock of the bike bumping on the road doesn't shorten the life of the hard drive) and collects speed, location and altitude at different time intervals. When you no longer need to collect data you can just turn off the data collection then turn it back on when you need it. It would be way less hassle then hooking up your computer every time you ride. You can move the data to a PC later to do detailed analysis if you want to.

The only other thing that may make sense would be to use a PDA with gps to do collect the data and analyze it later on.

Using a GPS would require almost no custom software, collect way more data than a normal bike computer and would be more durable.

If you REALLY wanted to use your bike computer's magnet couple with a computer you could use a PCMCIA card with an Analog to Digital converter and collect the pulses that way to find the speed. It would be most effective with a real-time operating system, but with something that simple I don't know that it would matter too much.
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Old 08-22-08, 12:53 PM   #6
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Does the computer have a parrallel port? I wrote some old school software for reading data off the parrallel port, the electronics for converting a coil's pulse to a high/low signal to the parrallel port would be simple. You'd then have a program running that just counts (and times) the pulses recieved on the parrallel port. This would be the cheapest solution possible (i could do it almost for free).

Although i must echo the comments stated above, i don't see the point.
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Old 08-22-08, 03:34 PM   #7
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No idea why you think for the convience of not having to push "stop" and "start" on a machine like a garvin, you want to carry an entire computer with you on the bike. That just doesn't make sense to me. The only advantage you're looking for is to skip the bus ride... just hit stop.
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Old 08-22-08, 05:00 PM   #8
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You'll need to build it yourself. This is easier than you can imagine! You want a Parallax BS1USB Board.
http://www.parallax.com/Store/Microc...8/Default.aspx



It has 8 input or output ports you can easily program.

You can make it wireless with a EmbeddedBlue Transceiver AppMod
http://www.parallax.com/Store/Microc...%2cProductName
Some one riding up to 300 feet behind you will be able to monitor everything you connect and program into the basic stamp microprocessor.

The simplest setup would be to salvage the sensor and magnet from a defunct wired cycle computer and connect to data ground and one of the 8 ports as an input port. This will send a pulse to the basic stamp input once every revolution of the wheel. Just figure out your tire circumference and figure out how many revolutions it makes per mile or kilometer. Adding cadence just involves another magnet and sensor exactly like the one on the wheel but you program it for RPM. You can add an LCD display if you like and a button or two to control it.
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