IC-MN_16 Datasheet, PDF (22/62 Pages) IC-Haus GmbH – 25-BIT NONIUS ENCODER WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION

iC-MN 25-BIT NONIUS ENCODER
WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION
Calibration Using
Comparated Sine/Cosine Signals
Rev F2, Page 22/62
Parameter
Output Signals
Op. Mode TRACMODE CALMODE BYP* Pins PSOUT, NSOUT, PCOUT, NCOUT Pin T0
Signal calibration modes with comparated sine/cosine signals
DIGO_M 1
1
Calib. signals of master chan.
DIGOFFCOS
DIGA_M 1
2
Calib. signals of master chan.
0
DIGP_M 1
3
Calib. signals of master chan.
0
DIGO_S 2
1
Calib. signals of segment chan.
DIGOFFCOS
DIGA_S 2
2
Calib. signals of segment chan.
0
DIGP_S 2
3
Calib. signals of segment chan.
0
DIGO_N 3
1
Calib. signals of nonius chan.
DIGOFFCOS
DIGA_N 3
2
Calib. signals of nonius chan.
0
DIGP_N 3
3
Calib. signals of nonius chan.
0
Pin T1
DIGOFFSIN
DIGAMP
DIGPHASE
DIGOFFSIN
DIGAMP
DIGPHASE
DIGOFFSIN
DIGAMP
DIGPHASE
Pin DIR
-
-
-
-
-
-
-
-
-
Table 10: Operating modes for digital signal calibration
Calibration Of Signal Offsets
Calibration Of Signal Amplitudes And Phase
Fig. 3: The duty ratio is set accurately to 50 % using
parameter OFS_x. This measurement requires a high
resolution, for instance of 0.06 %, for calibrating the
offset to 0.2 % with reference to the signal amplitude.
The resulting interpolation error of 3 LSB (referred to a
resolution of 13 bits) corresponds to an angle error of
0.11 degree (360 degree means one signal period).
Fig. 4: The duty ratio is set accurately to 50 % using
parameter OFC_x.
Fig. 5: To calibrate the duty cycle to exactly 50 % the
fine gain parameters GFC_x und GFS_x can balance
the signal amplitudes. If a signal amplitude difference
of 0.67 % remains after calibration, the interpolation
error enlarges to approx. 4.5 LSB at 13 bit resolution.
Fig. 6: Duty cycle calibration to exactly 50 % is carried
out using parameter PH_x. A remaining phase error of
0.7 degree reduces the interpolation accuracy to 10 bit
(equal to 8 LSB error at 13 bit resolution, respectively).
degree
0.2
0.1
0
-0.1
-0.2
0
90
180
270
360
Figure 3: Mode DIGO_x: DIGOFFSIN at Pin T1.
degree
0.2
0.1
0
-0.1
-0.2
0
90
180
270
360
Figure 5: Mode DIGA_x: DIGAMP at Pin T1.
degree
0.2
0.1
0
-0.1
-0.2
0
90
180
270
360
Figure 4: Mode DIGO_x: DIGOFFCOS at Pin T0.
degree
0.4
0.2
0
-0.2
-0.4
0
90
180
270
360
Figure 6: Mode DIGP_x: DIGPHASE at Pin T1.