NES in a Cartridge

Step 3 Testing the button simulator

This step isn't necessary, but it would definetly be a good idea to do it. So first I would download the TLC5940 library found here.
http://code.google.com/p/tlc5940arduino/downloads/list
Install it like your would with any Arduino library.
Then download the NES controller sketch (called "NES_micro_2_check.pde"). Go ahead and upload it onto your arduino board.

TLC5940:
Connect the TLC5940 as follows. I got this from the basic use sketch that comes with the library.
Arduino             TLC5940
13                      25
11                      26
10                      23
9                        24
3                        18
+5v                    19 & 21
GND                 22 & 27
GND   -WW-    20 (2K resistor goes from pin 20 to ground)

NES Port:
For this part, I just cut the wires on my stock NES controller port and wired them up according to this diagram.
  ___
| 1     \
| 2   5 |
| 3   6 |
| 4   7 |
 -------
1 = GND
2 = CLK
3 = Latch
4 = Data_Out
5 = +5VDC
6 = N/A
7 = N/A

Power Player:
Now solder some leads on to the button pads of your controller, make sure it's the NON common side of the pads.
Next, you can connect the leads up accordingly.
NES button                 TLC5940
Player One:
A                                  OUTPUT 0
B                                  OUTPUT 1
Select                         OUTPUT 2
Start                            OUTPUT 3
UP                               OUTPUT 4
DOWN                        OUTPUT 5
LEFT                           OUTPUT 6
RIGHT                         OUTPUT 7
Player Two:
A                                  OUTPUT 8
B                                  OUTPUT 9
Select                         OUTPUT 10
Start                            OUTPUT 11
UP                               OUTPUT 12
DOWN                        OUTPUT 13
LEFT                           OUTPUT 14
RIGHT                        OUTPUT 15

Finally, connect the system up to the TV, making sure that the arduino and the Power Player share the same power supply or their grounds are connected. Go ahead and test it out. If everything works good, then great! If not, then try to trouble shoot the problem.

Troubleshooting Tips:
1.     Test each output with an LED, connecting the long leg to +voltage, and the short leg to the TLC5940 output pins. If they don't work, then check the wiring of the TLC5940
2.     If all the LED's turn on when you press a button, then check the wiring on the controller port. This will occur when there are some wires switched around.
3.     Also make sure that your Power Player, or Super Joy, or other thing works off of common ground system. Meaning that when the buttons are pressed on the system, they short out to ground.