This feat is accomplished usinig an Arduino Leonardo.
MUST USE Arduino IDE VERSION 1.6.0 TO COMPILE PROPERLY (please refer here: https://www.instructables.com/id/Turn-an-N64-Controller-into-a-USB-Gamepad-using-an/ please read: "Step 1: Setting Up the Arduino Environment")
Arduino IDE VERSION 1.6.0 Found here: https://www.arduino.cc/download_handler.php?f=/arduino-1.6.0-windows.zip
tuned the joystick, as none of my n64 controllers were able to reach the max/min values of 127 and -127. they were only reaching values of around 80 or 90 and -80 or -90. (see: arduino->map) aslo added a small deadzone to the joystick. I added a switch function for debugging, and tweaked the output of it.