LB1847 stepper controller :how to connect to grbl atmega based board with step ,direction,enable , limit?
It seems that most people use an Arduino CNC Shield to connect their Arduino Uno (running GRBL software) to the drivers of the stepper-motors. Via Google you find plenty of them, for example: here and here. The schematics of the latter example are published here. You could use the information from this schematic to make your own 'interface' between the Arduino and the LB1847 driver chips.