The controller works in the forward direction. Speed control and braking works. Pictures and videos will be uploaded soon.
So far I have been following Roco.ca's h-bridge design. However, it requires AND gates. After attempting it in the lab today, I'm now abandoning that idea. It takes too many wires to do it, and the logic can be programmed in the Arduino. With this new philosophy, all of the logic will be handled by the Arduino. The number of output lines from the Arduino to the H-bridge will increase from 3 to 4, but the overall amount of wiring will decrease, and so will the overall footprint.