A CMOS 2D Micro-Fluxgate Earth Magnetic Field Detecting System with RS232 Digital Output

In this paper we present an acquisition system to measure the Earth magnetic field (whose full-scale value is of the order of 60 muT), consisting of a microcontrolled management subsystem, a CMOS integrated interface circuit and a 2D integrated micro-flux gate magnetic sensor. The couple of orthogonal axis of the sensor makes the system suitable for realizing an electronic compass device. The complete acquisition system achieves an accuracy resulting in a maximum error of 1.5deg in the measurement of the Earth´s magnetic field direction, providing a digital output through an RS232 serial interface. Furthermore a measurement setup was developed to evaluate the acquisition system performances. It consist of a precision mechanical structure, in tower form, of a PC software properly developed to post process the data from the acquisition system and of a Helmholtz Coils device to estimate the linearity of the system. This setup allows to perform a completely automated and numerically controlled characterization of the acquisition system.