Datasheet

TMC5160 DATASHEET (Rev. 1.01 / 2017-NOV-29) 83
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12.2.5 Application Example: Joystick Control
Applications like surveillance cameras can be optimally enhanced using the motion controller: while
joystick commands operate the motor at a user defined velocity, the target ramp generator ensures
that the valid motion range never is left.
REALIZE JOYSTICK CONTROL
1. Use positioning mode in order to control the motion direction and to set the motion limit(s).
2. Modify VMAX at any time in the range VSTART to your maximum value. With VSTART=0, you can
also stop motion by setting VMAX=0. The motion controller will use A1 and AMAX as determined
by V1 to adapt velocity for ramping up and ramping down.
3. In case you do not modify the acceleration settings, you do not need to rewrite XTARGET, just
modify VMAX.
4. DMAX, D1 and VSTOP only become used when the ramp controller slows down due to reaching
the target position, or when the target position has been modified to point to the other direction.
12.3 Velocity Thresholds
The ramp generator provides a number of velocity thresholds coupled with the actual velocity
VACTUAL. The different ranges allow programming the motor to the optimum step mode, coil current
and acceleration settings. Most applications will not require all of the thresholds, but in principle all
modes can be combined as shown in Figure 12.1. VHIGH and VCOOLTHRS are determined by the
settings THIGH and TCOOLTHRS in order to allow determination of the velocity when an external step
source is used. TSTEP becomes compared to these threshold values. A hysteresis of 1/16 TSTEP resp.
1/32 TSTEP is applied to avoid continuous toggling of the comparison results when a jitter in the
TSTEP measurement occurs. The upper switching velocity is higher by 1/16, resp. 1/32 of the value set
as threshold. The stealthChop threshold TPWMTHRS is not shown. It can be included with VPWMTHRS
< VCOOLTHRS.
high velocity fullstep
microstep + coolStep microstep + coolStep
microstepping microstepping
motor stand still
motor going to standby
motor in standby motor in standby
v
t
VSTOP
VSTART
0
V1
VMAX
AMAX
DMAX
D
1
A
1
VACTUAL
VCOOLTHRS
VHIGH
current
TZEROWAIT
RMS current
I_HOLD
I_RUN
dI * IHOLDDELAY
coolStep current reduction
Figure 12.3 Ramp generator velocity dependent motor control
The velocity thresholds for the different chopper modes and sensorless operation features are coupled
to the time between each two microsteps TSTEP.