TMC5031 DATASHEET (Rev. 1.11 / 2016-APR-28)
49
Optional Detection and Correction
This option risks the occurrence of the error and detects and corrects it. The irregularity of the
position counter can easily be detected by reading the counter twice whenever the motor is brought
to standstill (VZERO flag set). In case, two subsequent read accesses of XACTUAL show a different
result during standstill, the position is lost. Trigger a new homing sequence.
This solution will work well for applications with a low sequence of motion tasks, which allow doing
a new homing sequence. In case only one critical motion command per minute is issued, the mean
time to failure and automatic correction will be > 10 years.
9.6.2 TZEROWAIT and VSTART Restriction
This restriction applies in case that positioning mode is used with alternation of target-positions on-
the-fly, i.e. when a reversal of the motion direction can occur due to a change of the target position,
while the motor is moving.
In this case, set TZEROWAIT=0. Set VSTART to minimum 1 (or to a higher value) and VSTOP to the
lowest value usable for the application, e.g. 2.
Hint: Take care, that VSTOP is always required to be higher than VSTART, i.e. VSTOP must be minimum
2.
9.6.3 Stop Switch Handling Restriction
In case a stop switch is used for homing in conjunction with the automatic motor stop
(stop_l_enable=1 or stop_r_enable=1), a soft stop shall be used (set en_softstop=1). Set the deceleration
parameters to the desired value.
Hint: In any case, a homing requires use of the soft stop, as a hard stop might lead to motor step
loss. When reaching the reference switch, use the automatic position latch register in order to have
an exact reference of where the stop switch became active.
Use hard stop only for emergency stop. After a hard stop, initiate a new homing sequence, because
position might be lost.
Hint: There is no restriction of using a hard stop in conjunction with stallGuard2 (sg_stop=1). Hard
stop should be used with stallGuard in any case, as a stall event means, that the motor is forced into
stop.
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