Motor as Generator

I am attempting to use a small 3V motor as a generator to detect rotary motion. I assume I can use an analog pin to measure the incoming voltage. What kind of a circuit would I use to protect the Arduino from too much voltage?

Thanks.

to protect your arduino from the voltage, you will probably want a good-sized resistor (depending on the size of your motor) and a zener diode to protect overvoltage.... probably a 5v zener.