The parameter config::AxisConfig::uSteps was supposed to be
microstepping resolution, but it's instead being used as the driver's
MRES directly.
To avoid a runtime conversion, rename the field to mRes and define a new
enum listing all the possible (and valid) microstepping resolutions.
This simplifies the code and makes clear the stepsPerUnit scale.
Assign correct stepsPerUnit to all axes as a result, including working
limits.
Alex Voinea
D.R.racer
Yuri D'Elia