The blueNES 2 is a follow-up to the blueNES. Instead of using an Arduino, the blueNES 2 uses Adafruit’s Bluefruit. When connected to ground pins 0 – 11 on the Bluefruit will send a keyboard command. I’ve connected mine to an old NES controller. It’s that simple. The controller pinout I found on this Instructables.
Create your own wireless Bluetooth keyboard controller in an hour with the Bluefruit EZ-Key: it’s the fastest, easiest and bestest Bluetooth controller. We spent years learning how to develop our own custom Bluetooth firmware, and coupled with our own BT module hardware, we’ve created the most Maker-friendly wireless you can get!