The FSR Controller is connected to the correct FSR’s (normally 3) can be used to auto bed level 3d printers. The controller connects to the endstop on your printer and 3 FSR’s, it automatically adjusts the pressure on the FSR’s. When the the hot end or z probe hits the build plate, the board will detect this and trigger the end stop. The FSR controller is required to drive the Smoothie board with FSR’s.
Information available from JohnSL FSR Controller