User manual

TMCM-110-42 Manual 13
Copyright © 2005, TRINAMIC Motion Control GmbH & Co. KG
7 TMCM-110 Operational Description
7.1 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:
Parameter Description Range
f
CLK
Clock frequency 16 MHz
velocity 0..2047
a_max Maximum acceleration 0..2047
pulse_div Velocity pre-divider. The higher the value is, the less
is the maximum velocity.
Default value = 3
Can be changed in TMCL using SAP 154.
0..13
ramp_div Acceleration pre-divider. The higher the value is, the
less is the maximum acceleration
default value = 7
Can be change in TMCL using SAP 153.
0..13
Usrs Microstep resolution (microsteps per fullstep = 2
usrs
).
Can be changed in TMCL using SAP 140.
0..6
Table 7.1: TMC428 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 (microstep frequency change per second – the acceleration a) is
given by
29__
max
2
2
++
⋅
=
divrampdivpulse
CLK
af
a
This results in an acceleration in fullsteps of:
usrs
a
af
2
=
with af: acceleration in fullsteps