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TOPIC: Detecting Wheel Rotation - Reflective Tape or Paint - Ideas?

Detecting Wheel Rotation - Reflective Tape or Paint - Ideas? 9 months 3 weeks ago #18028

  • hop
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OUCH! Those are my notes you are deleting! lol No biggy, it's what I get for resurrecting such an old post anyway.

I think I said something about not needing the position of the wheel, and just need to get reliable pulses per revolution. You answered that my friend. I think I also spoke of the tech I will be using, which is a ESP01, STM32F103, and I haven't decided on a GUI device yet.

I am getting the pulse from reflective tape on the actual flywheel, near the center though and not the edge. This will reduce the speed it passes by and the needed size. I also decided on using a schmitt trigger for sending the pulse rather than reading the signal by the MCU. I have read about noisy ADC's on the STM32 line, and it will cut down on the overhead in the code. Then I can use the pulse with an interrupt instead.

I haven't decided on a circuit for the Schmitt Trigger circuit yet. I want it to be 3.3v but will be using a wire for the signal about 2-3 feet long, so I am not sure if I am going to go with 5vdc for the circuit and then attenuate the pulse voltage at the pin of the STM32. The devices in the tcrt5000 pair I am using commonly show a 5vdc source in the interface circuits I have browsed. With 5vdc, I can use a 7414 which I'm sure I have a lot of.

Some numbers I have calculated... at 18.5" in diameter, the surface area on the outer edge of the flywheel is 58.1195" or 4.8433 feet. So it would take 1094.68 revolutions to travel a mile. :) It's hard to gauge caloric burn using this data though. I guess I could sample the amount of time for the flywheel to decrease in speed over time, over a few values of resistance from zero to max, to estimate incline effort. That's for later and I do not have a solid weight measurement for the flywheel. That will be hard to do without taking it apart.
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