Using the SS49E linear Hall effect sensor in pairs on four sides of a square, the setup proves quite straightforward. Above the fixed sensor plate is a moveable magnet plate centred by a set of ...

might be specific to the sensor too. the ones im using puts out a signal between 1 and 4 volts. the adc expects 0 to 5. so you lose some resolution. you could do away with this with a double ended ...