How to read NES controller button presses with an Arduino

nes_controller.pde

/* This code is released into the public domain.
 * Pekka Väänänen, 2016 */
 
/*
  http://www.mit.edu/~tarvizo/nes-controller.html

          +----> Power +5V  (white)
          |
  5 +---------+  7
  | x  x  o   \
  | o  o  o  o |
  4 +------------+ 1
    |  |  |  |
    |  |  |  +-> Ground (brown)
    |  |  +----> Pulse  (red)
    |  +-------> Latch  (orange)
    +----------> Data   (yellow)
*/

#define BIT(x) (0x01 << (x))

const int LED = 13;
const int PULSE = 8; // red
const int LATCH = 10; // orange
const int DATA = 7; // yellow

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(PULSE, OUTPUT);
  pinMode(LATCH, OUTPUT);
  pinMode(DATA, INPUT);

  digitalWrite(LATCH, 0);
  digitalWrite(PULSE, 1);
  digitalWrite(DATA, 1); // data is up by default, goes to ground if key is pressed
}

#define BUTTON_A (0)
#define BUTTON_B (1)
#define BUTTON_SELECT (2)
#define BUTTON_START (3)
#define BUTTON_UP (4)
#define BUTTON_DOWN (5)
#define BUTTON_LEFT (6)
#define BUTTON_RIGHT (7)

char buttons[8];

void loop() {
    delayMicroseconds(16*1000);

    cli();
    digitalWrite(LATCH, 1);
    delayMicroseconds(12);
    digitalWrite(LATCH, 0);
    buttons[BUTTON_A] = 1 - digitalRead(DATA); // DATA goes to ground if button pressed
    delayMicroseconds(6);
    
    for (int i=1;i<8;++i) {
      digitalWrite(PULSE, 1);
      delayMicroseconds(6);
       buttons[i] = 1 - digitalRead(DATA);
      digitalWrite(PULSE, 0);
      
      delayMicroseconds(5);
    }

    sei();

    // Light up the LED if any key was pressed.
    int blink = 0;
    for (int i=0;i<8;++i) {
      blink = blink || buttons[i];
    }
    
    digitalWrite(LED, blink); 
}

hello,
i'm looking to make a pass-through LED indicator for an NES controller connected to a NES console (AVS).
would this work without interfering with the normal use of the controller/console?

i'm new to Arduino. not sure which device would be good today. the smaller/cheaper the better.

thanks!
/max

I'm really not an expert but you are going to need something tiny because there isn't much space inside the controller as you can see in this photo http://www.lofibucket.com/articles/img/nes_layout.jpg

thanks for the image.

i found someone who gave me a solution for LEDs that uses a couple of IC chips (like the ones found in a SNES controller) along with some resistors, and a couple of decoupling capacitors.
i'll be replacing the PCB with a blank prototype board. then populate it with the IC chips etc.

cheers