Implement electronic compass functionality in Android app

I'm developing an Android app. One of the features that have to be implemented is the electronic compass - the magnetic north must be shown on the screen (using the electronic compass IC in the smartphone (AK099xx, etc)). This code for this feature has been written, including the graphics (an arrow that rotates around its center), however, the problem is that implementation is not good. When I rotate the phone, the arrow is moving too and not showing North accurately. The required task: *** I need the arrow to stay locked on North, no matter how the phone is rotated in the horizontal plane. *** So you will be asked to write (re-write) the code in the best possible way to fit the requirements. I prefer a low-level implementation (NDK) rather than Java, for accuracy and speed. At project start, I will provide the application code, in its present stage. Notes: * Please bid only if you know exactly how to do this and you have past experience in this coding. (If you know how to do it, the volume of work shouldn't be very high.) * No need to touch other parts of the code; you should care only for the compass part. * If you think you don't have the proper knowledge, please don't bid. * High bids may not be considered. ##### DELIVERABLES ##### The new code, fulfilling the described requirements. Required knowledge: Android NDK, C, C++, Java