TMC262-EVAL MANUAL (V. 1.0 / 2011-Sep-07)
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Copyright © 2010 TRINAMIC Motion Control GmbH & Co. KG
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. You
can try both chopper modes over your full velocity range and decide afterwards, which one fits best. In
order to tune the chopper settings, you can follow the following instructions which are based on your
evaluation of motor behavior:
1. Start the motor at the desired velocity: For tuning of const t
OFF
mode fast decay time, a
medium velocity is preferred, e.g. 1-2 rotations per second. In order to tune chopper
hysteresis setting for standard chopper mode (spreadCycle), or sine wave offset in const t
OFF
mode, a low velocity should be preferred, e.g. 0.1-1 rotations per second.
2. Go to the tab CHOPCONF to choose the chopper mode and its settings. Now, you can select
standard chopper (spreadCycle) or classical const t
OFF
chopper.
3. For both modes, the off time t
OFF
is a major component. A setting between 2 and 7 fits most
motors for spread cycle, choose 4 to 15 for const t
OFF
chopper. A lower setting increases the
chopper frequency.
4. Now, you can tune the zero crossing behavior:
In the standard chopper mode, you can check behavior for different HSTART settings to
improve motor behavior: Start with a low HSTART setting and increase HSTART, until the
motor turns smoothest. If you reach maximum HSTART value, you might need to increase
HEND also. Further increasing the value will not bring further benefit.
In constant t
OFF
mode, a positive sine wave offset improves zero transition performance and
fast decay time influences motor resonance. You might try pure slow decay operation if fastest
motor velocity is desired. First, optimize fast decay time, starting from a low value, until the
motor turns smoothest. Further increasing fast decay time might be necessary for higher
velocity settings. As a second step, increase the sine wave offset starting from 0, until
smoothest motor operation is yielded. There will be an optimum setting at a certain value. A
higher setting causes a jump in the coil current sine wave zero crossing, a lower value causes
a flattening.
5. There is no need to modify the blank time, unless you change the MOSFETs on the board.
6.2 Writing the settings to a .C file
You can load and store all settings made in the evaluation board. They are stored in a .262 text file,
which is user readable.
figure 6: .262 file opened in text editor
In order to transfer the settings into your own software, there is a C language export function. This will
write out the initialization values for the TMC262 in a C syntax form, which allows easy sending via a
microcontroller SPI interface.
