const int dataPin = 9;   /* DS */
const int clockPin = 7;  /* SHCP */
const int latchPin = 8;  /* STCP */

uint8_t *scan[] = {10, 11, 12, 13, A0, A1, A2, A3, A4, A5};
uint8_t data[10];
uint8_t pos[2];

char *d[] = {"1 ","2 ","3 ","4 ","5 ","6 ","7 ","8 ","9 ","0 "};
int8_t power[] = {128,64,32,16,8,4,2,1};

String readString;

void clear() {
  for (int i = 0; i < 8; i++) {
    data[i] = 0;
  }
}

void printBin(byte aByte) {
  for (int8_t aBit = 7; aBit >= 0; aBit--) 
    Serial.write(bitRead(aByte, aBit) ? '1' : '0'); 
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Keyboard Emulation");
  for (int i = 0; i < 8; i++) {
    pinMode(scan[i], INPUT);
  }
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
}

void loop() {

  uint8_t pattern = 0;

  while (Serial.available()) {
    delay(3);  //delay to allow buffer to fill 
    if (Serial.available() >0) {
      char c = Serial.read();  //gets one byte from serial buffer
      readString += c; //makes the string readString
    } 
  }

  if (readString.length() >0) {

    clear();
    readString.toUpperCase();
    Serial.println(readString); //see what was received

    pos[0] = 255;
    pos[1] = 255;
    char *str = readString.c_str();
    for(int i =0; i < strlen(str); i++ ) {
      char c = str[i];

      switch(c) {
        case 'A':
        case 'B':
        case 'C':
        case 'D':
        case 'E':
        case 'F':
        case 'G':
        case 'H':
          pos[1] = c - 'A';
          break;
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
          pos[0] = c - '1';
          break;

        case '0':
          pos[0] = 9;
          break;
      }

      if (pos[0] != 255 && pos[1] != 255) {
        Serial.print(pos[0], DEC);
        Serial.print(" - ");
        Serial.println(pos[1], DEC);

        data[pos[0]] = data[pos[0]] | power[pos[1]];
        pos[0] = pos[1] = 255;
      }
      
    }

    Serial.println("  ABCDEFGH");
    for (int i = 0; i < 10; i++ ) {
      Serial.print(d[i]);
      printBin(data[i]);
      Serial.println("");
    }

    readString = "";
  }

  int button = 0;
  for (int i = 0; i < 10; i++) {
    int buttonState = digitalRead(scan[i]);
    pattern = 0;
    if (buttonState == HIGH) {
      pattern = data[i];      
      digitalWrite(latchPin, LOW);
      shiftOut(dataPin, clockPin, LSBFIRST, pattern);
      digitalWrite(latchPin, HIGH);
      button = 1;
    }
  }

  if (!button) {
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, LSBFIRST, pattern);
    digitalWrite(latchPin, HIGH);
  }
}