Arduino-RS232:Arduino的RS232接口电路

# Arduino-RS232 An RS232 interface circuit for Arduinos. It is general-purpose, but it is primarily intended to allow an Arduino to control a Roland Modela CNC mill (http://www.rolanddg.com/product/3d/3d/mdx-20_15/spec.html). This allows the Modela to mill PCBs under the control of the Arduino, including the PCB for the interface circuit itself. So you breadboard it and get it working. Then you mill its PCB. Then you take the components off your breadboard and solder them onto the PCB...