Very interesting what you are all working on. I thought that the train-automation was more or less dying.
I am using Arduino Nano's for the nodes. For reading the RFID's the nodes use a NFR522. For communication they use a NRF24L01. An Arduino mega is acting as a central control.
The trains have an Arduino as well, combined with a NRF24L01. At this time I still use the infrared receiver on the trains: the Arduino's on the trains have a infrared-LED to forward the commands. The advantage is that the trains can still be controlled with an infrared transmitter. But the drawback is the small amount of steps you can control the motor. And if the LED moves, the train does not get any commands anymore. There are projects in where an Arduino replaces the Lego IR receiver, might be interesting.
It is easy to setup: The first train drives an initialisation round and after that, the layout of the track is known.
I started as a nice small Arduino project, but to get it running, it was a bit more complex than I thought....
