TMCM-343 Hardware Manual (V1.07 / 2011-JUN-08)
23
Copyright © 2011, TRINAMIC Motion Control GmbH & Co. KG
10
TMCM-343 operational description
10.1
Calculation: Velocity and acceleration vs. microstep and
fullstep frequency
The values of the parameters sent to the TMC428 do not have typical motor values like rotations per
second as velocity. But these values can be calculated from the TMC428-parameters as shown in this
document.
The parameters for the TMC428 are:
Signal
Description
Range
f
CLK
clock-frequency
16 MHz
velocity
-
0… 2047
a_max
maximum acceleration
0… 2047
pulse_div
divider for the velocity. The higher the value is, the less
is the maximum velocity
default value = 0
0… 13
ramp_div
divider for the acceleration. The higher the value is, the
less is the maximum acceleration
default value = 0
0… 13
Usrs
microstep-resolution (microsteps per fullstep = 2
usrs
)
0… 7 (a value of 7 is
internally mapped to
6 by the TMC428)
Table 10.1: TMC428 velocity parameters
The
microstep-frequency
of the stepper motor is calculated with
32
2048
2
velocity
]
Hz
[
f
]
Hz
[
usf
div
_
pulse
CLK
with usf: microstep-frequency
To calculate the
fullstep-frequency
from the microstep-frequency, the microstep-frequency must be
divided by the number of microsteps per fullstep.
usrs
2
]
Hz
[
usf
]
Hz
[
fsf
with fsf: fullstep-frequency
The change in the pulse rate per time unit (pulse frequency change per second – the
acceleration a
)
is given by
29
div
_
ramp
div
_
pulse
max
2
CLK
2
a
f
a
This results in acceleration in fullsteps of:
usrs
2
a
af
with af: acceleration in fullsteps
