TMC2160 DATASHEET (Rev. 1.02 / 2018-NOV-19)
80
15.3 Stall Detection in dcStep Mode
While dcStep is able to decelerate the motor upon overload, it cannot avoid a stall in every operation
situation. Once the motor is blocked, or it becomes decelerated below a motor dependent minimum
velocity where the motor operation cannot safely be detected any more, the motor may stall and
loose steps. A stallGuard2 load value also is available during dcStep operation. The range of values is
limited to 0 to 255, in certain situations up to 511 will be read out. In order to enable stallGuard, also
set TCOOLTHRS corresponding to a velocity slightly above VDCMIN or up to VMAX.
Stall detection in this mode may trigger falsely due to resonances, when flywheel loads are loosely
coupled to the motor axis.
Parameter
Description
Range
Comment
vhighfs
&
vhighchm
These chopper configuration flags in CHOPCONF 0 / 1
need to be set for dcStep operation. As soon as
VDCMIN becomes exceeded, the chopper becomes
switched to fullstepping.
set to 1 for dcStep
TOFF
dcStep often benefits from an increased off time 2… 15
value in CHOPCONF. Settings >2 should be
preferred.
Settings 8…15 do not make
any difference to setting 8
for dcStep operation.
VDCMIN
This is the lower threshold for dcStep operation 0… 2^22 0: Disable dcStep
when using internal ramp generator. Below this
threshold, the motor operates in normal microstep
mode. In dcStep operation, the motor operates at
minimum VDCMIN, even when it is completely
blocked. Tune together with DC_TIME setting.
Set to the lower velocity
limit for dcStep operation.
Activation of stealthChop also disables dcStep.
DC_TIME
This setting controls the reference pulse width for 0… 1023 Lower limit for the setting
dcStep load measurement. It must be optimized
for robust operation with maximum motor torque.
A higher value allows higher torque and higher
velocity, a lower value allows operation down to
a lower velocity as set by VDCMIN.
is: tBLANK (as defined by
TBL) in clock cycles + n
with n in the range 1 to
100 (for a typical motor)
Check best setting under nominal operation
conditions, and re-check under extreme operating
conditions (e.g. lowest operation supply voltage,
highest motor temperature, and highest supply
voltage, lowest motor temperature).
DC_SG
This setting controls stall detection in dcStep 0… 255 Set slightly higher than
mode. Increase for higher sensitivity.
DC_TIME / 16
A stall can be used as an error condition by
issuing a hard stop for the motor. Stop the motor
upon an impulse on the stall output (configure
DIAG0 or DIAG1 to signal a stall). This way the
motor will be stopped once it stalls.
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TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
