help with Digital Compass Modules

even when I tell the servo to move to 22 - it make 2 circles.

Let's see if that makes sense. First off let's see what servo you have. The link says ...

Sail Winch Servo 55g metal gears 10.63kg torque 6 Turns travel

So it’s not a 720 deg servo, it’s a 6*360 = 2160 deg. A 22 deg command is 22/180 = 12.22% of a normal servos full range. 12.22% of 2160 deg is 264 deg, not even one turn. But then again each degree of command is 12 deg of rotation (ideally), and this servo might us a wider pulsewidth (than normal) for it’s turns.

So your command is about correct, certainly not 2 turns of command. Given the reviews I read over at HobbyKing for the 4 turn version of this servo (SW5513), it may well be that yours is broken. It seems to have quite a high failure rate.

http://www.hobbyking.com/hobbyking/stor … g_0_9.html