Smoothieware/Smoothieware — pull request #549 by PetteriAimonen (2014-11-23 19:50:53+00:00)
Title: Added spindle speed control module using PID feedback

Previously spindle speed has been controlled using the switch module PWM support. This new module implements feedback for spindle speed, which allows setting accurate RPM values.

Documentation in http://smoothieware.org/spindle-control