Motion engine control

AN4355

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DocID025240 Rev 2

2.2

Positioning commands

The motion engine, integrated into the devices, allows the position of the motor in a target

position based on integrated ABS_POS register.

The ABS_POS register traces all the motion performed by the motor adding a unit to each

microstep completed in forward direction and subtracting a unit when the microstep is

performed in reverse direction.

The target positioning can be directly imposed indicating the ABS_POS register value

(absolute position) or the distance between the current position and the target one (relative

position).

The relative positioning command is Move. The motion engine executes this command only

when the motor is stopped in order to avoid unexpected behaviors (e.g.: the target of

number of steps is not enough to allow the speed profile compliance).

Figure 4. Relative positioning command example

The absolute positioning commands are GoTo and GoTo_DIR. The former moves the motor

to the position target choosing the rotation direction according to a minimum path algorithm

(i.e.: the lower number of microsteps is executed) whereas the latter imposes the direction

directly.

Figure 5. Absolute positioning command example

0

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h000001

0

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h000001

Starting position

Starting position

Final position

Move(Reverse)

Move(Forward)

Final position

AM16590v1

0

h200000

h3FFFFF

h1FFFFF

h000001

0

h200000

h3FFFFF

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h000001

Starting position

Starting position

Target position

Target position

GoTo

GoTo_DIR(Forward)

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