iC-MH
12 BIT ANGULAR HALL ENCODER
Rev B1, Page 15/23
CALIBRATION USING INCREMENTAL SIGNALS
distance of the rising edge (equivalent to angle posi-
If test mode cannot be used, signals can also be cali- tions of 0° and 180°) at signal A should be exactly half
brated using the incremental signals or the values read a period (PER). Should the edges deviate from this in
out serially. In order to achieve a clear relationship be- distance, the offset of the sine channel can be adjusted
tween the calibration parameters which have an effect using VOSS. The same applies to the falling edges of
on the analog sensor signals and the digital sensor val- the A signal which should also have a distance of half
ues derived from these, the position of the zero pulse a period; deviations can be calibrated using the offset
should be set to ZPOS = 0 so that the digital signal of cosine parameter VOSC. With parameter GCC the
starting point matches that of the analog signals.
distance between the neighboring flanks of signals A
and B can then be adjusted to the exact value of an
eighth of a cycle (a 45° angle distance).
At an incremental resolution of 8 edges per revolu-
tion (CFGRES = 0x1) those angle values can be dis-
played at which calibration parameters VOSS, VOSC
and GCC demonstrate their greatest effect. When ro-
tating the magnet at a constant angular speed the in-
cremental signals shown in Figure 16 are achieved,
with which the individual edges ideally succeed one
another at a temporal distance of an eighth of a cy-
cle (a 45° angle distance). Alternatively, the angle po-
sition of the magnet can also be determined using a
reference encoder, rendering an even rotational action
unnecessary and allowing calibration to be performed
using the available set angle values .
The various possible effects of parameters VOSS,
VOSC and GCC on the flank position of incremental
signals A and B are shown in Figure 16. Ideally, the
Figure 16: Calibration using incremental signals
ICHAUS [ IC-HAUS GMBH ]
