IC-MN datasheet(49/62 Pages) ICHAUS

49 / 62 page

iC-MN 25-BIT NONIUS ENCODER

WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION

Rev F2, Page 49/62

Figure 23: Line signals of the serial MT interface

MODE_MT = 0x10 (SSI)

MT Interface with 2-bit mode

In this mode pin MTMA functions as an additional in-

put, besides pin MTSLI. The inputs now expect digital

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.

sector 0

sector 1

master

segment

nonius

calculated nonius position

max

MTMA

MTSLI

2 bit sector code (gray coded)

resulting dataword

2*max

max

iC-MN

360°

°/rev

Figure 24: Principle of 2-bit mode

Parameter

Description

MODE_MT = 11

MT interface op. mode: 2-bit mode

DL_MT = 0x0E

MT data length: 1 bit

SBL_MT = 00

Synchronization bit length: 1 bit

LNT_MT = 0 or 1

Depending on MTMA signal: leading or

trailing

GRAY_MT = 1

MT data format: Gray coded

M2S = 11

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

25 shows the required signal positions with leading

respectively trailing operation. The green arrows are

indicating the permissible relative position tolerances.

max

MTSLI

(LSB)

MTMA

(MSB)

sector 0

sector 1

MTSLI

(LSB)

MTMA

(MSB)

°/rev

binary

signal

binary

signal

Figure 25: 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 periods

per turn on iC-MN’s analog inputs. The nonius calcu-

lation would not produce absolute angle position data

over a single revolution since the maximum singleturn

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 example, 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.

IC-MN Datasheet(PDF) 49 Page - IC-Haus GmbH

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