TMC424-PI24 Trinamic Microchips, TMC424-PI24 Datasheet - Page 42

• Manufacturer Part Number: TMC424-PI24
• Description: Economic Miniature Three Axis Microstepping Stepper Motor Controller
• Manufacturer: Trinamic Microchips

TMC428 DATASHEET (V. 2.00 / November 12, 2003)
The shape parameter σ selects one of three functions f
superposition of two of them. The shape parameter σ = 0 selects the function f
function sin( ) as used for sine cosine microstepping. With this, one gets the unit circle (r=1.0) by
transformation to cartesian coordinates {y = sin( ); x = cos( )} as outlined in Figure 12-1, a shape
parameter σ = +1.0 results in a box, and a shape parameter σ = -1.0 results in a rhomb. Other values
except those, result in something between box and circle respectively something between circle an
rhomb.
The data values y(i) of the look-up table range from 0 to 63 and the argument i ranges also from 0 to
63. In the following, natural angles (radians) ranging from (0 ≤
The three functions for superposition controlled by the shape parameter σ are
All together, these three functions are combined to form the function
So, the shape parameter σ selects the type of function and it also provides a continuous transition
between circle and box respectively circle and rhomb. To estimate, what function would be best for a
given type of stepper motor, one can try microstepping based on different shape parameters σ by
downloading different microstep tables on-the-fly into the TMC428 during motion of a stepper motor.
For calculation of data for the microstep look-up table of the TMC428, one has to replace
from 0 to
The amplitude of the shape function f
range of 0 to 63 for the on-chip RAM as described in the beginning of the microstepping section.
13 How to get Started in Running a Motor
First of all, the Stepper Motor Driver Datagram Configuration has to be written into its RAM area.
Additionally, the Microstep Look-Up-Table has to be initialized when using microstepping. The
parameter LSMD, that is part of the global parameter register, has to be initialized. After that, the
parameters v_min, v_max, and the clock pre-dividers pulse_div and ramp_div and the microstep
resolution usrs has to be set. Then, a_max together with a valid pair of pmul and pdiv has to be set.
The switch configuration ref_conf together with the ramp mode rm has to be chosen. The reference
switch inputs REF1, REF2, REF3 should be pulled down to ground or disabled by setting ref_conf.
With those settings, the TMC428 runs a motor if one writes either x_target or v_target, depending on
the choice of the ramp mode rm.
Copyright © 2000–2003 TRINAMIC Microchips GmbH
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