A propeller, huh? Well I haven’t personally worked with a propeller but first and foremost it’s important to know when needing a motor to spin you will have to power it with secondary power source besides the arduino. The arduino doesn’t have enough current to drive the motor alone. That can be accomplished by putting a transistor (with something like 100ohm attached to the base of the transistor) to the pin you would like to use. Then connect the motor to the secondary power supply through the transistor. Since you are using a motot it’s best to use a PWM pin on the arduino.
If you already know that then next I would suggest using the arduino’s “map” function. The compass module will send numeric values from 0 to 360 (as floats i.e. 0.00) to the arduino and from there you can write your code based on the values received. So the map function might look something like “PWMpipn = map(0,360,0,1023);”. I can’t remeber if it’s 1023 or 255, but at any rate that funciton will translate the first values into the second values to be used proportionately on the PWM pin. The higher the number the faster it will spin.
This is all just a simple and fast stech to what I THINK would work…not sure if it will becuase I haven’t tested it. But start there. I hope that helped in some way. Sorry if it didn’t.
GOOD LUCK!