IC-MN Datasheet, PDF (48/59 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
MT Interface with 2-bit mode
In this mode pin MTMA functions as an additional in-
put, besides pin MTSLI. The inputs now expect digi-
tal signals phase shifted by 90°, whereas MTMA reads
the single bit period information, and MTSLI the shifted
synchronization bit. The following figure explains the
principle and the table below gives the necessary set-
tings.
calculated nonius position
max
max
sector 0
sector 1
0
360°
°/rev
.
2 bit sector code (gray coded)
0
360°
°/rev
.
master
segment
nonius
MTSLI
MTMA
iC-MN
resulting dataword
2*max
0
360°
°/rev
.
Figure 23: Principle of 2-bit mode
Rev D1, Page 48/59
max
max
sector 0
sector 1
MTSLI
MTMA
MTSLI
MTMA
0° 45° 90° 135° 180° 225° 270° 315° 0°
°/rev
Parameter
MODE_MT = 11
DL_MT = 0x0E
SBL_MT = 00
LNT_MT = 0 or 1
GRAY_MT = 1
M2S = 11
Description
MT interface op. mode: 2-bit mode
MT data length: 1 bit
Synchronization bit length: 1 bit
Depending on MTMA signal: leading or
trailing
MT data format: Gray coded
Enable for MT plus ST data output
Table 89: Required settings for 2-bit mode
The required position of the multiturn and synchro-
nization bit depends on parameter LNT_MT. Figure 24
shows the required signal positions with leading re-
spectively trailing operation. The green arrows are in-
dicating the permissible relative position tolerances.
Figure 24: Position of switch points in reference to
the parameter LNT_MT
A typical application example where the 2-bit mode can
be used for, is a magnetic angle encoder scanning the
pole wheel by MR sensors. A nonius coded wheel of
16, 15 and 12 pole pairs yields 32, 30 and 24 sine pe-
riods per turn on iC-MN’s analog inputs. The nonius
calculation would not produce absolute angle position
data over a single revolution since the maximum sin-
gleturn value is achieved twice. The distinction as to
which half of the revolution the axis is in can only be
made using section sensors, two Hall sensors for ex-
ample, whose digital outputs are connected up directly
to MTMA and MTSLI. Furthermore, the 2-bit mode can
be used also with systems based on a 2 track nonius
calculation.