TMC223 DATASHEET (V. 1.05 / March 7, 2011)
9
5 Functional Description
5.1 Position Controller and Main Controller
5.1.1 Stepping Modes
The TMC223 supports up to 16 micro steps per full step, which leads to smooth and low torque ripple
motion of the stepping motor. Four stepping modes (micro step resolutions) are selectable by the user
(see also Table 11):
•
•
•
•
Half step Mode
1/4 Micro stepping
1/8 Micro stepping
1/16 Micro stepping
5.1.2 Velocity Ramp
A common velocity ramp where a motor drives to a desired position is shown in the figure below. The
motion consists of a acceleration phase, a phase of constant speed and a final deceleration phase.
Both the acceleration and the deceleration are symmetrical. The acceleration factor can be chosen
from a table with 16 entries. (Table 5: Acc Parameter on page 12). A typical motion begins with a start
velocity Vmin. During acceleration phase the velocity is increased until Vmax is reached. After
acceleration phase the motion is continued with velocity Vmax until the velocity has to be decreased in
order to stop at the desired target position. Both velocity parameters Vmin and Vmax are
programmable, whereas Vmin is a programmable ratio of Vmax. (See Table 3: Vmax Parameter on
page 11 and Table 4: Vmin on page 12). The user has to take into account that Vmin is not allowed to
change while a motion is ongoing. Vmax is only allowed to change under special circumstances. (See
5.1.4 Vmax Parameter on page 11).
The peak current value to be fed to each coil of the stepper-motor is selectable from a table with 16
possible values. It has to be distinguished between the run current Irun and the hold current Ihold. Irun
is fed through the stepper motor coils while a motion is performed, whereas Ihold is the current to hold
the stepper motor before or after a motion. More details about Irun and Ihold can be found in 5.3.1. and
5.3.2.
Velocity resp. acceleration parameters are accessable via the serial interface. These parameters are
written via the SetMotorParam command (see 6.8.9) and read via the GetFullStatus1 command (see
6.8.1).
Velocity V
[FS/s]
Vmax
Vmin
time
[s]
Xstart
Xtarget
No
Movement
Acceleration
Phase
Deceleration
Phase
No
Movement
State of Motion
Constant Velocity
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