I haven't touched this project in a long time. However I have found a project that is up and running which uses the Arduino Uno/Mega to generate the DCC signal and also uses a L298 Motor Shield to act as a booster for the DCC signal. This project is DCC++ and listed below are some useful links for it:
Also there are two Raspberry Pi SPROG modules:
- Pi-SPROG One
- Pi-SPROG Nano
More information can be found at the Pi-SPROG webpage.