All my tests on the USB output card ended so now it's time to start thinking to the input interface, for switches and buttons.
Taking inspiration from a good idea of Dave, I tried to transform an USB keyboard to an input interface. Essentially, disassembling the keyboard, I get the little circuit and with some connections and solders I am able to build an interface to connect switches and buttons.
Shorting any couple of pins I simulate a keypress (every combination is a different key). With a lot of patience, using an old flat cable (restored from an old IDE Hard Disk) I connect every single pin of the keyboard circuit to the breadboard. It has been a long and hard work because of pins are very small and closer each others.
Here is the achieved result:
Flat calbe soldered to the keyboard circuit:
The other edge of flat cable linked to the breadboard:
After a lot of attempts to get the right combinations, I mapped all the sim's commands through FSUIPC library. By this way, connecting switches / buttons to the breadboard I can control the sim. So, I made some tests using switches:
Mapped all the commands, now it's time to buy and connect real buttons.