iC-MH
12 BIT ANGULAR HALL ENCODER
Rev B1, Page 14/23
Vsin
the gain factor, as shown in Figure 12, have no effect
on the Lissajous curve, enabling the angle information
for the interpolator to be maintained.
VOSS
Vsin
a
GAING
GAINF
Vcos
a
C141107-3
Vcos
Figure 13: Effect of the sine offset setting
Vsin
VOSC
C141107-2
Figure 12: Effect of gain settings GAING and
GAINF
a
Deviations of the observed Lissajous curve from the
ideal circle can be corrected by varying the ampli-
tude offset (register VOSS, VOSC) and amplitude ratio
(register GCC). Changes in these parameters are de-
scribed in the following figures 13 to 15. Each of these
settings has a different effect on the interpolated angle
value. A change in the sine offset thus has a maximum
effect on the angle value at 0° and 180°, with no al-
terations whatsoever taking place at angles of 90° and
270°. When varying the cosine offset exactly the oppo-
site can be achieved as these angle pairs can be set
independent of one another. Setting the cosine/sine
amplitude ratio does not change these angles (0°, 90°,
180° and 270°); however, in-between values of 45°,
135°, 225° and 315° can still be influenced by this pa-
rameter.
Vcos
C141107-4
Figure 14: Effect of the cosine offset setting
Vsin
GCC
a
Once calibration has been carried out a signal such as
the one illustrated in Figure 11 should be available.
Vcos
In the final stage of the process the amplitude control
can be switched back on (ENAC =1) to enable devi-
ations in the signal amplitude caused by variations in
the magnetic field due to changes in distance and tem-
perature to be automatically controlled.
C141107-5
Figure 15: Effect of the amplitude ratio
ICHAUS [ IC-HAUS GMBH ]
