As promised in the previous post, some pieces of information about the H-Bridge: we are considering to change our initial choice of the IC A4973 to one simpler and smaller (A4953, A4950). I have not had the time to read the datasheets, but they look quite similar to an A4973, except it does not have a internal PWM. Basically, it is perfect for us.
A couple of things about the locomotive: unfortunately, there are only two white LEDs, one in the front of the locomotive and the other in the rear. That means we cannot simulate the real-life behavior (white/white, red/red, white/red, red/white). At least, it is easier to control, we could even use one GPIO high-drive mode. The following photo illustrates:
Alexis is getting the library ready with the devices we are going to need. I expect to finish the design and begin the routing process soon.