there is a simple solution. At least in the event that you only want to test the driver hardware.
The individual motor drivers are controlled via 4 pins per axis.
In the source code file Movement.cpp, 3 of these 4 pins are defined in the loadSettings () method. The 4th pin is a ChipSelect that is assigned to the respective axis in TMS2130.h.
The AUX ChipSelect pin is missing in the definition of all pins and has to be added in pins.h:
#define AUX_CHIP_SELECT 43
If you then swap the line e.g. in Movement.cpp
axisZ.loadPinNumbers (Z_STEP_PIN, Z_DIR_PIN, Z_ENABLE_PIN, Z_MIN_PIN, Z_MAX_PIN, 0, 0, 0);
axisZ.loadPinNumbers (AUX_STEP_PIN, AUX_DIR_PIN, AUX_ENABLE_PIN, Z_MIN_PIN, Z_MAX_PIN, 0, 0, 0);
and in TMS2130.h the line
static TMC2130_Basics TMC2130Z (Z_CHIP_SELECT);
static TMC2130_Basics TMC2130Z (AUX_CHIP_SELECT);
after uploading the newly compiled firmware, the AUX MOTOR driver will be used for the Z-axis.
The whole thing can also be interesting if you are not using an auxiliary motor, but one of the axis drivers should have burned out. In this way, the AUX driver can be configured as a redundant replacement for the defective driver.