System and method for calibrating a magnetometer with visual affordance

1. A method of calibrating a magnetometer of a portable electronic device, the method comprising:

displaying a visual indication of a gestural path on a display of the portable electronic device, wherein the visual indication comprises a reticule and a target, wherein changes in the orientation of the portable electronic device cause a position of the reticule to move relative to the target;

monitoring for changes in orientation of the portable electronic device;

changing the visual indication in response to the monitored changes in the orientation of the portable electronic device;

measuring a magnetic field with the magnetometer; and

calibrating the magnetometer in accordance with measurements of the magnetic field acquired at different points along the gestural path.

2. The method of claim 1 further comprising moving the portable electronic device along the gestural path.

3. The method of claim 1 wherein the gestural path represents a plurality of orientations of the portable electronic device, wherein the magnetic field is measured in at least some of the plurality of orientations of the gestural path.

4. The method of claim 3 wherein the magnetic field is measured at all of the plurality of orientations of the gestural path.

5. The method of claim 3 wherein the plurality of orientations of the gestural path correspond to a series of gestures in the orientation of the portable electronic device, wherein the series of gestures includes a tilt left, tilt up, tilt down and tilt right.

6. The method of claim 1 wherein the visual indication only changes in response to changes in the orientation of the portable electronic device which match the gestural path.

7. The method of claim 1 wherein the calibrating is performed when a threshold number of measurements of the magnetic field at predetermined points along the gestural path have been measured.

8. The method of claim 1 wherein the calibrating comprises performing a calibration operation to obtain one or more calibration parameters and storing the obtained calibration parameters.

9. The method of claim 8 further comprising measuring the magnetic field with the magnetometer and adjusting the measurements of magnetic field in accordance with the stored calibration parameters.

10. The method of claim 1 wherein the reticule has a fixed position relative to the display and the target has a fixed position relative to a user interface screen displayed on the display.

11. The method of claim 1 wherein the reticule changes in appearance when the position of the reticule matches a position of the target.

12. The method of claim 1 wherein the reticule and target overlay an image provided by a camera of the portable electronic device.

13. The method of claim 1 wherein the reticule moves at a speed proportional to a sampling rate of the magnetometer.

14. A method of calibrating a magnetometer of a portable electronic device, the method comprising:

displaying a visual indication of a gestural path on a display of the portable electronic device, wherein the visual indication comprises a track and an object moveable within the track in response to changes in the orientation of the portable electronic device, wherein changes in the orientation of the portable electronic device cause a position of the object to move within the track;

monitoring for changes in orientation of the portable electronic device;

changing the visual indication in response to the monitored changes in the orientation of the portable electronic device;

measuring a magnetic field with the magnetometer; and

calibrating the magnetometer in accordance with measurements of the magnetic field acquired at different points along the gestural path.

15. The method of claim 14 wherein the position of the object within the track only changes in response to changes in the orientation of the portable electronic device which match the gestural path.

16. The method of claim 14 wherein the object is a ball.

17. The method of claim 14 wherein the object is a flowing liquid.

18. The method of claim 14 wherein the object moves at a speed proportional to a sampling rate of the magnetometer.

19. A portable electronic device, comprising:

a processor;

a magnetometer coupled to the processor;

a display coupled to the processor;

wherein the processor is configured for: displaying a visual indication of a gestural path on the display, wherein the visual indication comprises a reticule and a target, wherein changes in the orientation of the portable electronic device cause a position of the reticule to move relative to the target; monitoring for changes in orientation of the portable electronic device; changing in the visual indication in response to the monitored changes in the orientation of the portable electronic device; measuring a magnetic field with the magnetometer; and calibrating the magnetometer in accordance with measurements of the magnetic field acquired at different points along the gestural path.

20. A portable electronic device, comprising:

a processor;

a magnetometer coupled to the processor;

a display coupled to the processor;

wherein the processor is configured for: displaying a visual indication of a gestural path on the display, wherein the visual indication comprises a track and an object moveable within the track in response to changes in the orientation of the portable electronic device, wherein changes in the orientation of the portable electronic device cause a position of the object to move within the track; monitoring for changes in orientation of the portable electronic device; changing in the visual indication in response to the monitored changes in the orientation of the portable electronic device; measuring a magnetic field with the magnetometer; and calibrating the magnetometer in accordance with measurements of the magnetic field acquired at different points along the gestural path.