IC-MHM Datasheet, PDF (21/63 Pages) IC-Haus GmbH – 14-BIT ABSOLUTE ANGLE HALL ENCODER

iC-MHM
14-BIT ABSOLUTE ANGLE HALL ENCODER
INTERPOLATOR
Rev D1, Page 21/63
The internal interpolator in the iC-MHM converts the
conditioned sine and cosine signals from the Hall sen-
sors into an angular position value with a configurable
resolution of between 9 and 14 bits. This angular posi-
tion is available over the serial interface in BiSS, SSI,
or SPI modes. In addition, the digital I/O port can be
configured to output the change in position as incre-
mental quadrature signals. Refer to DIGITAL I/O PORT
on page 26 for more information.
Singleturn Resolution (RESO_ST)
The singleturn resolution of the iC-MHM is determined
by the interpolator resolution as set using parameter
RESO_ST.
RESO_ST Address 0x00; bits 6:4
Value
Resolution: Bits
0
16
1
15
2
14
3
13
4
12
5
11
6
10
7
9
Counts or Edges per
Revolution
65 536
32 768
16 384
8 192
4 096
2 048
1 024
512
Code Direction (DIR)
The positive direction of rotation (increasing angular po-
sition) is determined by parameter DIR and the enable
preset input P1 (if enabled).
If the enable preset input P1 is not used (DIR_IO2 = 0),
then with DIR = 0, counterclockwise rotation of the mag-
net when viewed from the top of the iC-MHM results
in increasing angular position. This can be inverted by
setting DIR = 1, in which case clockwise rotation of the
magnet results in increasing angular position.
DIR
Value
0
1
Address 0x00; bit 5
Positive Rotation
Counterclockwise (Normal)
Clockwise (Inverted)
Table 17: Code Direction (DIR_IO2 = 0)
If the enable preset input P1 is used (DIR_IO2 = 1),
then parameter DIR is exclusive-ORed with the state of
the code direction input to determine the positive code
direction.
Table 15: Singleturn Resolution
Note: Resolutions above 12 bits require use of the
averaging filter (AVGFILT =/ 0). Resolutions above 14
bits are not recommended.
Rot. Dir. DIR
Input
0
0
0
1
1
0
1
1
Positive Rotation
Counterclockwise (Normal)
Clockwise (Inverted)
Clockwise (Inverted)
Counterclockwise (Normal)
Averaging Filter (AVGFILT)
The averaging filter is enabled using parameter AVG-
FILT to allow singleturn resolutions above 12 bits.
AVGFILT
Value
0
1
2
3
Address 0x00; bits 1:0
Filter
None
Light
Medium
Heavy
Typical Latency
0.0 µs
1.2 µs
2.3 µs
4.6 µs
Table 16: Averaging Filter
Table 18: Code Direction (DIR_IO2 = 1)
Refer to DIGITAL I/O PORT on page 26 for information
on configuring the enable code direction input P2 and
parameter DIR_IO2.
Parameter DIR and the enable code direction input P2
(if enabled) also reverses the direction of the incremen-
tal quadrature outputs, if used (CFG_IOP = 2). Refer to
Incremental Quadrature (ABZ) Outputs on page 29 for
information on using the digital I/O port as incremental
encoder (ABZ) outputs.
While the averaging filter allows higher resolutions, it
reduces the maximum magnet rotation speed and also
introduces latency into the position measurement. For
fastest response and highest magnet rotation speed,
disable the filter (AVGFILT = 0) and use an interpolator
resolution of 12 bits or less (RESO_ST ≥ 4).
Hysteresis (HYS)
Hysteresis is used to prevent flickering of the angular
position LSBs and dithering of the incremental quadra-
ture outputs. The amount of hysteresis is determined
by parameter HYS.