TMC2100 DATASHEET (Rev. 1.07 / 2017-MAY-15)
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11.4 INDEX Output
An active INDEX output signals that the sine curve of motor coil A is at its positive zero transition.
This correlates to the zero point of the microstep sequence. Usually, the cosine curve of coil B is at its
maximum at the same time. Thus the index signal is active once within each electrical period, and
corresponds to a defined position of the motor within a sequence of four fullsteps. The INDEX output
this way allows the detection of a certain microstep pattern, and thus helps to detect a position with
more precision than a stop switch can do.
Current
COIL A
COIL B
0
Time
INDEX
STEPS
Current
Time
Time
Figure 11.3 Index signal at positive zero transition of the coil A sine curve
Attention
The duration of the index pulse corresponds to the duration of the microstep. When working without
interpolation at less than 256 microsteps, the index time goes down to two CLK clock cycles.
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