pora_code.ino

const uint16_t val_1   =   (1 << 0);
const uint16_t val_2   =   (1 << 8);
const uint16_t val_3   =   (1 << 1);
const uint16_t val_4   =   (1 << 9);
const uint16_t val_5   =   (1 << 2);
const uint16_t val_6   =   (1 << 10);
const uint16_t val_7   =   (1 << 3);
const uint16_t val_8   =   (1 << 11);
const uint16_t val_9   =   (1 << 4);

const uint16_t val_ent =   (1 << 12);

const int CLOCK_PIN = 13;
const int INPUT_PIN = 12;
const int OUTPUT_PIN = 8;

const int LATCH_PIN = 11;

void setup() {
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(INPUT_PIN, OUTPUT);
  pinMode(OUTPUT_PIN, INPUT);
  pinMode(LATCH_PIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // When the stuff breaks!

  // Enter code
  Serial.print("Test");
  prepare_button(val_4);
  while (digitalRead(OUTPUT_PIN) == LOW);
  Serial.print("DEBUG --- PRESSED 4!");

  prepare_button(val_6);
  while (digitalRead(OUTPUT_PIN) == LOW);
  Serial.print("DEBUG --- PRESSED 6!");

  prepare_button(val_9);
  while (digitalRead(OUTPUT_PIN) == LOW);
  Serial.print("DEBUG --- PRESSED 9!");

  prepare_button(val_2);
  while (digitalRead(OUTPUT_PIN) == LOW);
  Serial.print("DEBUG --- PRESSED 2!");

  prepare_button(val_ent);
  while (digitalRead(OUTPUT_PIN) == LOW);
  Serial.print("DEBUG --- PRESSED ENTER!");
  // Code entered

  Serial.print("DEBUG --- CODE ENTERED!");
}

void prepare_button(uint16_t button){
  digitalWrite(CLOCK_PIN, HIGH);

  digitalWrite(INPUT_PIN, (int)button);

  digitalWrite(CLOCK_PIN, LOW);
  digitalWrite(LATCH_PIN, HIGH);
  digitalWrite(LATCH_PIN, LOW);
}