NES USB Joystick Adapter with Digispark post

The Digispark is a tiny Arduino compatible (with restrictions) USB enabled development board. A while ago I baked their Kickstarter campaign but didn't made anything with my Digisparks until this week. I finally tried to connect one to another item I bough long ago, an original NES controller.

Consuming a NES controller with an Arduino is actually easy, a quick googling returns tons of working code. There is even an Arduino library which looks like it could work on a Digispark. Exposing the the Digispark as an USB Joystick is even easier, thanks to the DigiJoystick library which is itself based on the well known V-USB (if you ever googled the "arduino usb" keywords, then you've already encountered v-usb).

I ended with the following code, which seems to do the job. Unfortunately, my NES controller revealed itself to be broken, the left button is always seen as pressed except when down is pressed.

#include "DigiJoystick.h"

#define LATCH   1
#define CLOCK   2
#define DATA    5
#define UP      B00001000
#define DOWN    B00000100
#define LEFT    B00000010
#define RIGHT   B00000001
#define BUTTONS B11110000

byte state = 0;

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

  digitalWrite(LATCH,HIGH);
  digitalWrite(CLOCK,HIGH);
}

void loop() {
  // Read controller's state
  state = 0;
  digitalWrite(LATCH,LOW);
  digitalWrite(CLOCK,LOW);
  digitalWrite(LATCH,HIGH);
  delayMicroseconds(2);
  digitalWrite(LATCH,LOW);
  state = ~digitalRead(DATA);
  for (int i = 1; i <= 7; i ++) {
    digitalWrite(CLOCK,HIGH);
    delayMicroseconds(2);
    state = state << 1;
    state = state + ~digitalRead(DATA) ;
    delayMicroseconds(4);
    digitalWrite(CLOCK,LOW);
  }
  // set USB Joystick state.
  DigiJoystick.setY((byte)127);
  if (state & UP) {
    DigiJoystick.setY((byte)0);
  }
  if (state & DOWN) {
    DigiJoystick.setY((byte)255);
  }
  DigiJoystick.setX((byte)127);
  if (state & LEFT) {
    DigiJoystick.setX((byte)0);
  }
  if (state & RIGHT) {
    DigiJoystick.setX((byte)255);
  }
  DigiJoystick.setButtons((char)((states>>4) & BUTTONS), (char) 0);
  DigiJoystick.delay(10);
}