Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
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Read entire documentation; especially the “Supplemental Directives” on page 224.
 MAIN MANUAL 
Incremental Encoders: Index Signal: N resp. Z
The index signal (N or Z channel) represents a recurrence of the same position in one motor
encoder revolution. TMC4361A makes use of this signal to clear the external position counter,
or to take a snapshot of the external or internal position, which then can be used to refine the
home position more precisely.
Figure 62: Outline of ABN Signals of an incremental Encoder
Per default, the index channel is configured low active.
In order to set up high active polarity for the index channel, do as follows:
Action:
 Set pol_n =1 (register ENC_CONF 0x07).
Result:
The index channel is high active.
The active polarity of the index channel can be used to clear the external position
counter or to take a snapshot of the external or internal position. Therefore,
N event is created internally. N event is based on the active polarity of the index
channel. As addition, they can also be based on the polarities of the
A and B channels.
Four active polarity configuration options for the index channel are available, which
are presented below. Configuration choice depends on customer-specific design
wishes.
In order to set up the index channel sensitivity based on active polarity, do
as follows:
Action:
 Set n_chan_sensitivity (register ENC_CONF 0x07) to:
Index Channel Sensitivity
n_chan_sensitivity
Result
b’00
N event is active in case index voltage level fits pol_n.
b’01
N event is triggered when the index channel switches to
active polarity.
b’10
N event is triggered when the index channel switches to
inactive polarity.
b’11
N event is triggered at both edges when the index channel
switches to either active or inactive polarity.
Table 58: Index Channel Sensitivity
 Description continued on next page.
A
B
t
Position
-4 -3 -2 -1 0 5 64321 7
N
Setup of Active
Polarity for
Index Channel
Configuration of
N Event
Index Channel
Sensitivity