IC-MH_17 Datasheet, PDF (17/26 Pages) IC-Haus GmbH – 12-BIT ANGULAR HALL ENCODER

iC-MH
12-BIT ANGULAR HALL ENCODER
Rev C2, Page 17/26
SINE/DIGITAL CONVERTER
The iC-MH module integrates two separate sine/digital
converters. A high-resolution 12-bit converter for the
ABZ incremental signals can be programmed in broad
ranges of the resolution and generate quadrature sig- _A
nals even at the highest speed and resolution. The
converter operates for the commutation signals inde-
pendently of this and can be set in the zero point sepa- B
rately from the quadrature converter. This enables the
commutation at other angles based on the index track
Z.
Z
100%
Figure 17: ABZ signals and relative accuracy
CFGRES(7:0)
0x0
1
0x1
2
...
...
0x7e
127
0x7f
128
0x80
256
0x81
512
0x82
1024
Addr. 0x06; bit 7:0
The incremental signals can be inverted again indepen-
dently of the output drivers. As a result, other phase
angles of A and B relative to the index pulse Z can be
generated. The standard is A and B high level for the
zero point, i.e. Z is equal to high.
Table 15: Programming interpolation factor
The resolution of the 12-bit converter can virtually be
set as desired. Any resolution can be set up to an in-
terpolation factor of 128, i.e. 512 edges per rotation.
At higher resolutions, only the binary resolutions can
be set, i.e. 256, 512 and 1024. In the highest resolu-
tion with an interpolation factor of 1024, 4096 edges
per rotation are generated and 4096 angular steps can
be differentiated. Even in the highest resolution, the
absolute position can be calculated in real time at the
maximum speed. After the resolution is changed, a
module reset is triggered internally and the absolute
position is recalculated.
Figure 17 shows the position of the incremental signals
around the zero point. The relative accuracy of the
edges to each other at a resolution setting of 10 bit is
better than 10%. This means that, based on a period
at A or B, the edge occurs in a window between 40%
and 60%.
CFGHYS(1:0)
Addr. 0x08; bit 7:6
0x0
0,17°
0x1
0,35°
0x2
0,7°
0x3
1,4°
Table 17: Programming angular hysteresis
CFGAB(1:0)
Addr. 0x08; bit 1:0
0x0
A and B not inverted
0x1
B inverted, A normal
0x2
A inverted, B normal
0x3
A and B inverted
Table 16: Inversion of AB signals
With rotating direction reversal, an angular hysteresis
prevents multiple switching of the incremental signals
at the reversing point. The angular hysteresis corre-
sponds to a slip which exists between the two rotating
directions. However, if a switching point is approached
from the same direction, then the edge is always gener-
ated at the same position on the output. The following
figure shows the generated quadrature signals for a
resolution of 360 edges per rotation (interpolation factor
90) and a set angular hysteresis of 1.4°.