iC-MH8
12 BIT ANGULAR HALL ENCODER
Rev A0.9, Page 18/25
Sine/Digital Converter
100%
The iC-MH8 module integrates a high-resolution
sine/digital converter. In the highest output resolution
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 abso-
lute position can be calculated in real time at the max-
imum speed.
A
B
Z
This absolute position is used to generate quadrature
signals (ABZ) and commutation signals (UVW). The
zero point of the quadrature signals and the commu-
tation signals can be set seperately. This enables the
commutation at other angles based on the index track
Z.
Figure 17: ABZ signals and relative accuracy
The incremental signals can be inverted again inde-
pendently 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.
The resolution of the incremental output signals is pro-
grammed with CFGRES.
The value of the 12-bit sine-digital converter is avail-
able in full resolution in the ’Extended SSI-Mode’ and
in a resolution according to CFGRES in the ’SSI-
Mode’.
Figure 17 shows the position of the incremental sig-
nals 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%.
CFGRES(2:0)
Addr. 0x06; bit 3:0
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
1024
512
256
128
64
32
16
8
CFGHYS(1:0)
Addr. 0x08; bit 7:6
0x0
0x1
0x2
0x3
0,17°
4
0,35°
0,7°
2
1
1,4°
Table 15: Programming interpolation factor
Table 17: Programming angular hysteresis
After the resolution is changed, a module reset is trig-
gered internally and the absolute position is recalcu-
lated.
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 gen-
erated at the same position on the output. The fol-
lowing 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°.
CFGAB(1:0)
Addr. 0x08; bit 1:0
A and B not inverted
0x0
0x1
0x2
0x3
B inverted, A normal
A inverted, B normal
A and B inverted
Table 16: Inversion of AB signals
ICHAUS [ IC-HAUS GMBH ]
