Introduction: Bluetooth NES Controller Mod

Parts you'll need:
NES controller - $5 (I had one with a dead IC: Perfect)
Adafruit Bluefruit EZ-Key HID - $20
Kensington Pocket Battery k38056us - $16
Toggle Switch $4
CD tray opener switch
LED
Dremel Bits - $15 (WOW)

Step 1: Back of the Controller

I started by making some room for the battery. The one I used is 3.7v 1200mAh which for this controller is definitely overkill.
I removed a post because I needed room for the charging circuit/EZ-Key but I had room above the buttons and behind the board so this was unneccesary.

Step 2: Front of the Controller

I had already performed the LED logo mod and I reused the face. Don't pay attention to anything but the hole behind the logo because that's where the CD drive opener switch will go.

Step 3: Battery / Charging Circuit

This is the battery/ charging circuit. If you need to make room for the charge circuit you can solder the connectors for the USB cable/battery to the other side of the board.

Step 4: Controller Board

I cut the board right above the lower solder points to reuse the dpad connections. but I overlooked the start/select B and A buttons so I had to solder onto the traces to get those working again. This could probably have been left alone, but I had a dead IC.

The solder point labled GND - L will be the ground for all of the buttons, the EZ-Key sends button down events when the inputs are pulled to ground so you need 9 wires total: GND - L, Right, Left, Down, UP, A B Select and Start.

These solder right onto the EZ-Key's inputs

If you wanted to wire them so the buttons will sort of match up it would be:

Controller to EZ-Key Mapping:
GND-L to EZ-Key Ground
Right to #3
Left to #2
Down to #1
Up to #0
Start to #4
Select to #5
B to #6
A to #7

Keep your wires short there's not much room in the case.

Step 5: Wiring

If you wanted to wire the inputs so the buttons will sort of match up it would be:

Controller to EZ-Key Mapping:
GND-L to EZ-Key Ground
Right to #3
Left to #2
Down to #1
Up to #0
Start to #4
Select to #5
B to #6
A to #7

The power switch will break the positive or negative lead going from the charge circuit to the battery so we're not wasting power when it's off.

Keep your wires short there's not much room in the case.

Step 6: Final Product

Congratulations!

You've somehow managed to cram all of that stuff into this little case. Turn it on with the switch, check the LED placeholder to see if you've got power, test that pair button, connect it to your PC or phone, send some key-presses map the buttons in an emulator and enjoy!