This configuration drives a standard 4-axis 3D printer using the PRU for high speed step/dir pulse generation and a CRAMPS driver board. 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. If you have limit switches, uncomment the marked lines in the HAL file to enable them. 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'.