This adapter lets you mount your phone on to an original xbox controller in the memory card slots. To connect an phone, cut the controller cable off and splice on a usb cable (leave the yellow wire disconnected), and then use a microusb otg adapter to connect to the phone. tested in cyanogenmod 10 and 11 on a samsung galaxy s relay and a samsung galaxy note 2. Works great in mupen. To save weight, remove the rumble motors. You CAN make an otg adapter (pictured is my own) if you are cheap by soldering the select pin to ground and replacing the USB A male end with a female, or they are available on ebay for a buck.
Originally, this was for n64 controllers and mounted in the controller pak slot. I included that model too.