Step 3: Building the master module
Building this module will depend on what Arduino 328 based MCU you want to use. I chose the Ardweeny because it was cheap and small and I had two on hand. I mounted components on a perf board from my junk box. I used hobby servo interconnect cables between modules. The Ardweeny requires a 5VDC supply, other Arduinos may not. See schematic and photo for details.