#include <Keypad.h>
#include <LiquidCrystal.h>
LiquidCrystal lcd(10, 11, 2, 3, 4, 5, 6, 7, 8, 9);
char bOut[7];
char num[4] = "000";
char format[4] = "000";
char previous[4] = "111";
char hexOut[6] = "";
char hexNum[3];
unsigned long debounceTime;
int keyPos = 0;
int hexPos = 0;
byte outByte;
bool hexRead = false;
bool binReset[10];
const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '0', 'F', 'E', 'D' }
};

uint8_t colPins[COLS] = { 35, 36, 37, 38 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 31, 32, 33, 34 }; // Pins connected to R1, R2, R3, R4

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  pinMode(39, OUTPUT); //LCD anode
  digitalWrite(39, HIGH); 
  lcd.begin(16,2);
  lcd.setCursor(2, 0);
  for (int i = 0; i <=8; i++) {
    pinMode(i + 20, INPUT_PULLUP);
  }
  for (int i = 0; i <=8; i++) {
    pinMode(i + 40, OUTPUT);
  }
  printByte();
  lcd.setCursor(12,1);
  lcd.print("0");
}

void loop() {
  char key = keypad.getKey();
  if (key != NO_KEY) {
    GetNumber(key);
  }
  
  refresh();
  binaryCounter();
}
void printByte() {
  
  for (int i = 0; i < 8; i++) {
    lcd.setCursor(7-i,0);
    lcd.print(bitRead(outByte, i));
  }
  lcd.setCursor(9,1);
  lcd.print(hexOut);
  if (!hexRead){
    lcd.setCursor(keyPos, 1);
    }
  for (int i = 0; i < 8; i++) {
    digitalWrite(47 - i, bitRead(outByte, i));
  }
}
int GetNumber(char key)
{
  if (!hexRead){
   switch (key)
   {
     case NO_KEY:
      break;

    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9':
      num[keyPos] = key;
      if (atoi(num) >= 255) {
        strcpy(num, "255");
      }
      lcd.cursor();
      lcd.setCursor(keyPos,1);
      lcd.print(num[keyPos]);
      keyPos++;
      key = NO_KEY;
      break;
   
      case 'A':
    case 'B': case 'C': case 'D': case 'E': case 'F':
    hexRead = true;
    lcd.blink();
    lcd.setCursor(hexPos + 11,1);
    return;
    break;
   }
  }
   if (hexRead){
     switch(key){
     case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9': case 'A':
    case 'B': case 'C': case 'D': case 'E': case 'F':
      hexNum[hexPos] = key;
      if (StrToHex(hexNum) >= 255) {
        strcpy(hexNum, "FF");
      }
      lcd.blink();
      lcd.setCursor(hexPos + 11,1);
      outByte = StrToHex(hexNum);
      sprintf(num, "%03d", outByte);
      lcd.print(hexNum[hexPos]);
      ++hexPos;
      key = NO_KEY;
      break;
     }
  }
}
void binaryCounter() {
  
  for (int i = 0; i <=8; i++){
    int j = (9-i);
  if (!digitalRead(j + 20) && binReset[j]){
    bitWrite(outByte, i, !bitRead(outByte, i));
    sprintf(num, "%03d", outByte);
    binReset[j] = false;
    refresh();
  }
  else if (digitalRead(j + 20) && millis() - debounceTime >= 20){
    binReset[j] = true;
    debounceTime = millis();
  }
  }
}
void refresh() {
  if (keyPos >= 3) {
    keyPos = 0;
    lcd.noCursor();
  }
  if (hexPos > 1) {
       hexPos = 0;
       hexRead = false;
       return;
     }
  if (atoi(num) != atoi(previous)) {
      lcd.setCursor(0, 1);
      lcd.print(num);
      lcd.setCursor(keyPos,1);
      strcpy(previous, num);
      outByte = byte(atoi(num));
      sprintf(hexOut, "0x%02%X", outByte);
      printByte();
  }
  if (!hexRead) {
    lcd.noBlink();
  }
}
int StrToHex(char str[])
{
  return (int) strtol(str, 0, 16);
}