Compass sensor code in Android app

I'm developing an Android app and one of the features implemented is the electronic compass. The code for the animation graphics (a rotating arrow that should indicate North) has been completed. Now I want the code for the sensor data to be written very accurately, by a pro in this field. The magnetic north must be detected and shown on the screen very accurately; therefore I need the code to be the most highly accurate code possible (including NDK). The required task: *** The arrow must stay locked on North, no matter how phone is rotated in the horizontal plane, with minimum inertia *** While filtering the noise a bit may be necesary (if it causes the indicator to tremble), I need a maximum reaction speed and a minimum inertia (delay / delay) in graphic's indication. A low level implementation (NDK / C) rather than Java (at least partly) is desired. 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 with such code. (If you know how to do it, the volume of work shouldn't be very high.) * If you think you don't have the proper knowledge, or experience please don't bid. ##### DELIVERABLES ##### The new code, fulfilling the described requirements. Required knowledge: Android NDK, C, C++