PD-1140 Datasheet, PDF (23/26 Pages) TRINAMIC Motion Control GmbH & Co. KG. – Stepper Motor with Controller

PD-1140 Hardware Manual (Rev. 1.02 / 2013-MAR-26)
23
10 PD-1140 Operational Description
10.1Calculation: Velocity and Acceleration vs. Microstep and
Fullstep Frequency
The values of the parameters sent to the TMC429 do not have typical motor values like rotations per
second as velocity. But these values can be calculated from the TMC429 parameters as shown in this
section.
PARAMETERS OF TMC429
Signal Description
Range
f_CLK
velocity
clock-frequency
-
16 MHz
0… 2047
a_max
maximum acceleration
0… 2047
divider for the velocity. The higher the value is, the less is
pulse_div the maximum velocity
0… 13
default value = 0
divider for the acceleration. The higher the value is, the
ramp_div less is the maximum acceleration
0… 13
default value = 0
Usrs
microstep-resolution (microsteps per fullstep = 2^usrs)
0… 8 (a value of 7 or 8 is internally
mapped to 6 by the TMC429)
Table 10.1 TMC429 velocity parameters
MICROSTEP FREQUENCY
The microstep frequency of the stepper motor is calculated with
usf [Hz]  ^{fCLK [Hz]  velocity}
2 ^{pulse_ div}  2048  32
with usf: microstep-frequency
FULLSTEP FREQUENCY
To calculate the fullstep frequency from the microstep frequency, the microstep frequency must be
divided by the number of microsteps per fullstep.
fsf
[Hz]

usf [Hz]
2^usrs
with fsf: fullstep-frequency
The change in the pulse rate per time unit (pulse frequency change per second – the acceleration a) is
given by
a
f _CLK ²  a_max
2 ^{pulse_ divramp_ div29}
This results in acceleration in fullsteps of:
a
af 
2^usrs
with af: acceleration in fullsteps
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