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TMC211 DATASHEET (V. 1.04 / January 7, 2005)
6.12 Positioning Task Example
The TMC211 has to perform a positioning task, where the actual position of the stepper motor is
unknown. The desired target position is 3000 µsteps away from position 0. See Figure 18: Positioning
Example: Initial situation.
Stop
Actual
Position
=
Target
Position
= 3000
unknown
?
?
X [µsteps]
?
Position 0
Figure 18: Positioning Example: Initial situation
The following sequence of commands has to be sent to the slave in order to complete the scenario
described above (assumed after power on):
GetFullStatus
The command is used to read the current status of the TMC211. Electrical or environmental problems
will be reported, furthermore the circuit leaves the shutdown state and is ready for action.
Furthermore the circuit provides the actual and target position. This information is very important,
because if the actual position corresponds to the first target position of the RunInit command the circuit
will enter a deadlock state. The master must take care that both positions are containing different
values.
See 6.11.2 GetFullStatus command on page 36 and for deadlock problems see 5.1.11 Reference
Search / Position initialization on page 14.
SetMotorParam
In order to drive the stepper motor with desired motion parameters like torque, velocity, a.s.o.. the
SetMotorParam command must issued. See 6.11.10 SetMotorParam on page 42.
RunInit
Hence the actual position is unknown, a position initialization has to be performed. The first motion
must drive the stepper motor into the stop for sure. The second motion is a very short motion to bring
the motor out of the stop. The actual position is then set to zero automatically after the second motion
is finished. See 6.11.9 RunInit command on page 41.
After reference search the actual situation looks like as described in Figure 19: Positioning Example:
Situation after reference search. Actual position of the stepper motor corresponds to zero, the target
position is 3000 µsteps away from the actual position.
Stop
Actual
Position
= 0
Target
Position
= 3000
X [µsteps]
Figure 19: Positioning Example: Situation after reference search
Now the positioning command SetPosition can be issued in order to drive the stepper motor to the
desired position.
Copyright © 2004-2005 TRINAMIC Motion Control GmbH & Co. KG
TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
