TMC389-EVAL MANUAL (V. 1.10 / 2011-Mar-01)
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Copyright © 2010 TRINAMIC Motion Control GmbH & Co. KG
range o/-10, probably your velocity setting is too high or too low. If the SG value reaches zero
far before the motor stalls, increase the SGT value.
The optimum setting is reached, when the stallGuard2
™ value reaches zero at increasing load shortly
before the motor stalls due to overload.
Now, you are ready to enable coolStep™! Go to the SMARTEN tab and set SEMAX and SEMIN to a
value different from 0. This enables coolStep. A good value for both is 1 or 2 for most motors. Now,
coolStep is enabled and you should see the current scale SE decreasing when the motor does not see
any load (see tab Graph). You can modify current increase and current reduction speed by changing
SEUP and SEDN. You can select, if the current becomes scaled down to ½ of CS or to ¼ of CS, using
SEIMIN setting.
For details and sample traces, please see the TMC389 data sheet.
Hint:
For first tests, we recommend setting SEIMIN to ½, as the ¼ setting might not work stable with
increasing load without adapting the SGT value to the actual motor current.
6.1.6
Optimizing the chopper settings
In principle, you can run the motor with default settings, but you might want to try improving or
modifying the chopper setting for smoothest performance of the motor and for low chopper noise. Start
the motor at the desired velocity, e.g. a medium velocity to tune const toff mode fast decay time, or a
low velocity to tune chopper hysteresis setting or sine wave offset in const toff mode. Go to the tab
CHOPCONF. There is no need to modify the blank time, unless you change the MOSFETs on the
board. For most motors, you can work without chopper off time (NOSD box checked). You can check
motor microstep behavior and chopper noise (should not come into the audible range) for different
HYST settings to improve motor behavior. Chopper synchronization (CSYNC) will improve behavior at
higher motor velocity.
figure 7: Evaluation software: Chopper settings
