USB interface

This USB interface board receives the orders coming from the PC on the USB bus and send them to the target module which can be a PWM driver, or a Device Controller or a Train Detector.
It also polls the PWM and Train Detector modules to scan for the train presence.
The USB Interface module has a single USB bus connected to the PC and it can supervise one or two serial busses for communicating with the control modules. The second bus is optional and it is only recommenced for controlling layouts with more than 25 modules.
Here is a picture of the USB interface board wired in its minimal configuration.