[Ben Heck] posted an interesting one-off project he built many months ago. Video game developer Infinity Ward approached him to build a large display that indicated what buttons on a controller were being pressed. They were planning on using it during player testing by recording the board and the monitor at the same time. They could then compare the two to see if there was any disconnect between the players input and the onscreen action. Infinity Ward is the developer behind games like Call of Duty 4.
[Ben] piggy-backed the switch connections and added an external port. He used a pair of octal buffer ICs to replicate the signals and activate the LEDs. The whole board is powered by the same 3.3V line that’s used by accessories like the chat pad. The triggers have three LEDs each and are lit using a resistor ladder. [Ben] comments that since this is a newer Xbox 360 controller, the active-low button scheme makes it fairly easy to work with. There is a video of the board embedded below.