NES-controller.ino

NES-controller.ino

/* Quick and dirty NES to DMG button driver (originally by Mr.Blinky)
 *
 * Using digital pins so it can be easily run on any Arduino
 * Because DigitalRead and DigitalWrite are pretty slow, no delays are
 * required when changing controller pin states and reading in data
 */

//NES button state masks
#define BS_A      _BV(7)
#define BS_B      _BV(6)
#define BS_SELECT _BV(5)
#define BS_START  _BV(4)
#define BS_RIGHT  _BV(3)
#define BS_LEFT   _BV(2)
#define BS_UP     _BV(1)
#define BS_DOWN   _BV(0)

//DMG button driver pins
#define P10  A0
#define P11  A1
#define P12  A2
#define P13  A3
#define P14   2
#define P15   3

//NES controller pins
#define CONTROLLER_DATA  4
#define CONTROLLER_LATCH 5
#define CONTROLLER_CLOCK 6

volatile uint8_t buttons_state = 0xFF;

void setup()
{
  //Serial.begin(9600);
  //NES controller pins
  pinMode(CONTROLLER_DATA,  INPUT_PULLUP);
  pinMode(CONTROLLER_LATCH, OUTPUT);
  pinMode(CONTROLLER_CLOCK, OUTPUT);

  //DMG button driver pins
  pinMode(P10, OUTPUT);
  pinMode(P11, OUTPUT);
  pinMode(P12, OUTPUT);
  pinMode(P13, OUTPUT);
  pinMode(P14, INPUT_PULLUP);
  pinMode(P15, INPUT_PULLUP);

  attachInterrupt(digitalPinToInterrupt(P14), interruptP14, FALLING);
  attachInterrupt(digitalPinToInterrupt(P15), interruptP15, FALLING);
}

void interruptP14()
{
  PORTF = (buttons_state & 0x0F) << 4;
}

void interruptP15()
{
  PORTF = (buttons_state & 0xF0);
}

void updateButtonState(uint8_t button)
{
  if (digitalRead(CONTROLLER_DATA)) buttons_state |=  button;
  else                              buttons_state &= ~button;
  digitalWrite(CONTROLLER_CLOCK, HIGH); //clock out next button state
  digitalWrite(CONTROLLER_CLOCK, LOW);
}

void loop()
{ //read controller button states
  digitalWrite(CONTROLLER_LATCH, HIGH); //parallel load controller button states
  digitalWrite(CONTROLLER_CLOCK, LOW);  //ensure clock is low when switching to serial mode
  digitalWrite(CONTROLLER_LATCH, LOW);  //switch to serial mode
  updateButtonState(BS_A);
  updateButtonState(BS_B);
  updateButtonState(BS_SELECT);
  updateButtonState(BS_START);
  updateButtonState(BS_UP);
  updateButtonState(BS_DOWN);
  updateButtonState(BS_LEFT);
  updateButtonState(BS_RIGHT);

  if (PIND & B00000011) PORTF = 0xF0;
  //Serial.println(buttons_state, BIN);
}

@HoZy88 the code by @MrBlinky that I adapted this from in the first place is much closer to what you are looking for - here it is, the original and the best: https://github.com/MrBlinky/Arduboy/blob/master/SNES-controller/SNES-controller.ino

Can we get a version of this for Atmega328?