AN4241

Motion engine

Doc ID 024193 Rev 1

9/18

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

If a GoTo command is requested when the motor is running, the minimum path algorithm

also considers the steps required to reverse the direction (see Figure 6).

Figure 6.

Minimum path algorithm when motor is running

The GoTo and GoTo_DIR can only be executed when no other commands are under

execution.

2.2.1

Change the target position of the on-the-fly command

If a Run command is sent to the device during the execution of a GoTo command, it aborts

the previous command. This effect can be used to change the target position of the motion

engine on-the-fly.

0

h200000

h3FFFFF

h1FFFFF

h000001

0

h200000

h3FFFFF

h1FFFFF

h000001

Starting position

Starting position

Target position

Target position

GoTo

GoTo_DIR(Forward)

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0

h200000

>

then forward direction is used.

h3FFFFF

h1FFFFF

h000001

Current position

Zero speed position

(where the motor will stop if it starts decelerating)

Target position

Motor is running

in forward direction

Forward direction path

Forward direction path

Reverse direction path

Reverse direction path

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