Datasheet

TMCM-1180 and PD86-1180 Hardware Manual (V1.05 / 2013-JUL-26) 23
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8 TMCM-1180 Operational Description
8.1 Calculation: Velocity and Acceleration vs. Microstep and
Fullstep Frequency
The values of the parameters sent to the TMC428/429 do not have typical motor values like rotations per
second as velocity. But these values can be calculated from the TMC428/429-parameters as shown in this
section.
PARAMETERS FOR THE TMC428/429
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
Table 8.1 TMC428/429 velocity parameters
The microstep-frequency of the stepper motor is calculated with
3220482
][
][
_



divpulse
CLK
velocityHzf
Hzusf
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
Hzusf
Hzfsf
2
][
][ 
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__
max
2
2



divrampdivpulse
CLK
af
a
This results in acceleration in fullsteps of:
usrs
2
a
af 
with af: acceleration in fullsteps