Design for 2-axis digital compass with magnetoresistive sensor and microcontroller

By using magnetoresistive sensor HMC1022 made by Honeywell,a smart 2-axis electronic compass has been developed.The amplifier AD8656 is used as the signal conditioning circuit.The microcontroller C8051F350 is in charge of A/D converting,azimuth computing and digital outputting.As the sensor’s reset circuit is involved so that the error due to null and drift can be minimized.The calibration for hard iron effects and soft iron effects is also be discussed.The maximum of azimuth error is less than 1° in the test.