As of October 4, 2016, RiceCNC is making the complete firmware source code available in the hope of picking up support from open source authors. However, it is being released under GNU GPLv3 license such that bug fixes and additions will remain public domain.

The included downloadable firmware will perform coordinated interpolations for up to nine axes with micro-stepping accuracy at ultrasonic frequency. The firmware can interpolate any combination of linear and cubic bezier splines. Cubic bezier spline interpolation will enable your machine to follow any path in multi-dimensional space without sending a high number of points to the micro-controller. The logic will conserve motor momentum when possible between interpolation, i.e., look-ahead is supported.

Many users are familiar with cubic bezier splines used in drawing programs. Although cubic bezier curves are not circular, the approximation is very close ( less than 0.02% radial error ) for arcs of 90°. The system uses smaller arc angles for large diameter circles to provide even greater accuracy.