A method and system for determining the position of a movable member in an electronic
input device within a predefined resolution. Two offset signals indicate the position
of the movable member. The time required for each signal to cross a threshold level
is measured and inverted, revealing an offset sinusoidal relationship. The offset
sinusoids may be plotted against each other to reveal an approximate circle of
inverse time samples for a cycle. Corresponding inverted minimum and maximum times
are used to determine a center reference value for each signal. As a function of
the inverted times, a quadrant of the circle is determined. Within a quadrant,
a sector most closely corresponding to the position of the movable member is determined
from among a plurality of predefined sectors that define the resolution. A number
of sectors between position samples of the movable member are accumulated and communicated
to a host device.
