Have you ever wondered just how much your hamster runs throughout the day/night? How far? How fast? The results are unbelievable.
The measurement system is very simple. The laser break beam sensor will be aimed at a small target on the wheel that will only reflect the beam once per full rotation of the wheel. The Pi will detect each time the wheel turns a full rotation and calculate the distance traveled and speed (the distance traveled is simply the circumference of the wheel). The resulting measurements will be captured and streamed to a data visualization that you can look at when you wake up each morning (because your hamster is probably getting his workout on while you sleep at night).
The laser break beam sensor from Adafruit is a good choice for this project because of its simplicity to wire up and use. No extra weight will be added to the wheel to make it harder to spin for your 2 oz. dwarf hamster. Both the laser transmitter and receiver are built into the same small plastic housing. If the laser beam reflects off of a target within 1 meter or so, the receiver detects and outputs the break. This is much better than a traditional laser break sensor that requires a separate receiver that must be aligned to the laser (like your garage door sensor that can easily get off track if you touch it). The laser break beam sensor will have three wires to attach. Attach the red wire to 5V. Attach the black wire to ground. The blue wire will be the sensor output. Connect this wire to a 10K ohm pull-up resistor and to an input pin on your Pi as shown below. *Warning* Do not shine the laser into the living area of your hamster!!! You could cause damage to your hamster’s eyes. If your wheel is inside the cage, consider using a magnetic contact switch instead of a laser break beam sensor.
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