
This configuration drives a standard 4-axis 3D printer using the PRU for
high speed step/dir pulse generation, a BeagleBone Black, a BeBoPr++
interface board and four Pololu type stepper drivers.

There are currently no limit switches configured, so adjust the MIN_LIMIT
and MAX_LIMIT axis settings in the ini file if your printer has less than
200 mm of X/Y travel.

Current X and Y settings are appropriate for a typical "MendelMax" style
printer, with the following settings:

max vel   = 200 mm/s
max accel = 3000 mm/s/s
scale     = 80 steps/mm

Adjust as required for your machine.  Make scale negative to invert any
axis that is moving 'backwards'.
