Magnetic sensor digital processing interface for electrical motor application

A system for an interface for magnetic sensors to determine an angle of rotation comprising:

• an arrangement of anisotropic magnetoresisitive (AMR) sensors providing analog sine and cosine values of the angle to be determined;
• two identical measurement paths to process said sine and cosine values each, comprising each a second order delta-sigma modulator operating with an over-sampling ratio to perform amplification and analog-to-digital conversion of said sine orrespective cosine values, a low-pass decimation filter having a sincM characteristic performing the filtering and down-sampling of the delta-sigma modulator bit stream, a normalization stage using offset and scaling normalization parameters having input and output wherein the input is the output of said low-pass decimation filter and the output is the input of a processor to compute the angle to be determined;
• a COordinate Rotational Digital Computer (CORDIC) processor to compute the angle to be determined by decomposing the desired rotation angle into iterations of pre-defined elementary rotation angles performing the rotation operation by simple shift-and-add operations replacing multiplication/division operations and the magnitude of the vector MAG=√{square root over (sin2+cos2)} using the output from both said normalization stages;
• a register file to store said rotation angle and said vector magnitude;
• and
• a 16-bit peripheral bus interface of a micro-controller. having as input the output of said register file.

A method for an interface for magnetic sensors to determine an angle of rotation comprising:

• providing an arrangement of magnetic sensors providing sine and cosine values of said rotational angle, two measurement paths comprising a pair of delta-sigma modulators, a pair of decimation filters and a pair of normalization stages, further a processor, a register file and a processor interface to external devices;
• perform first analog-to digital conversion of sine and cosine values provided by magnetic sensors;
• then
• perform low-pass filtering and down-sampling of digitized bit stream;
• then
• normalize sine and cosine values to correct offset and scaling deviations;
• then
• compute desired rotation angle;
• and
• shift computed values of rotation angle and vector magnitude into register file.