#include "TimerOne.h"
#include "Wire.h"
#include "LiquidCrystal_I2C.h"

LiquidCrystal_I2C lcd(0x27,16,2);   //add, 16x2 lcd 
int inEMPin = 6;   // sensing digital pin 7

#define maxASKBuf 300 //reduce to 100 or so for debugging
#define debug  0 // 0=disabled, 1= loq debug printing, 2 = high debug mode  

//char rawFSK[maxFSKBuf];
//unsigned int final[65];
    
unsigned long CountryCode = 0;
unsigned long CardNumber = 0;
unsigned long CardNumberMSB = 0;
int FDX_detected = 0;
int errorbit = 0;

#define   ValidRelay 2 //green
#define   ValidLED 12 //green
#define   ReadyLED 11 //red

void setup()
{
  lcd.init();                      // initialize the lcd 
  lcd.backlight();
  lcd.setCursor(0,0); 
  lcd.print("FDX Ready!");

  Serial.begin(9600);
  Timer1.initialize(8);  // initialize timer1, and set the frequency; this drives both the LC tank as well as the pulse timing clock
  // note: modify this as needed to achieve resonance and good match with the desired tags
  // the argument value is in microseconds per RF cycle, so 8us will yield RF of 125kHz, 7us --> 143kHz, etc.

  Timer1.pwm(9, 512);           // setup pwm on pin 9, 50% duty cycle

  pinMode(inEMPin, INPUT);      // sets the digital pin 6 as input to sense receiver input signal
  pinMode(ReadyLED, OUTPUT);
  pinMode(ValidLED, OUTPUT);
  pinMode(ValidRelay, OUTPUT);
  digitalWrite(ReadyLED, 1);
  digitalWrite(ValidLED, 0);
  digitalWrite(ValidRelay, 0);
  if(debug >= 1) {  Serial.print("Reader Started.");  }
}


void loop()
{  
  int loop;
  FDX_detected = 0;
  CountryCode = 0;
  CardNumber = 0;

//  if(debug >= 0){  Serial.print("\nready...");  }

 // Wait for card to be detected
  while (digitalRead(inEMPin) == 0) {}  // Wait for Initial high state

  loop = 0;
  while (loop <= 3) { 
    FDX_detected = 0;
    read_fdx(); 
    if (FDX_detected == 1) {break;}
    loop = loop + 1;  
  }
//  Control_Valid(500);            
if (FDX_detected == 1) { 
  lcd.clear();
  lcd.setCursor(0,0); 
  lcd.print("FDX");

  lcd.setCursor(0,1); 
  LeadingZeros(CountryCode, 3);
  lcd.print((unsigned long)CountryCode);
  lcd.print("-");
  LeadingZeros(CardNumber, 12);
  lcd.print((unsigned long)CardNumber);  

  Control_Valid(2000);            
  
  lcd.clear();
  lcd.setCursor(0,0); 
  lcd.print("Reader Ready!");
  lcd.setCursor(0,1);    
  }
}


//-----------------------------------------------------------------------

void LeadingZeros(unsigned long Value, int Digits) {

  if (Digits == 3){
    if ((Value > 0) && (Value <= 9)) { lcd.print("00");}
    else if ((Value > 9) && (Value <= 99)) { lcd.print("0");}
    else if ((Value > 99) && (Value <= 999)){ lcd.print("");}
    else {}  
  }
  if (Digits == 12){
    if ((Value > 0) && (Value <= 9)) { lcd.print("0000000000");}
    else if ((Value > 9) && (Value <= 99)) { lcd.print("000000000");}
    else if ((Value > 99) && (Value <= 999)){ lcd.print("00000000");}
    else if ((Value > 999) && (Value <= 9999)){ lcd.print("0000000");}
    else if ((Value > 99999) && (Value <= 999999)){ lcd.print("000000");}
    else if ((Value > 999999) && (Value <= 9999999)){ lcd.print("00000");}
    else if ((Value > 9999999) && (Value <= 99999999)){ lcd.print("0000");}
    else if ((Value > 99999999) && (Value <= 999999999)){ lcd.print("000");} 
    else if ((Value > 999999999) && (Value <= 9999999999)){ lcd.print("00");} 
    else if ((Value > 9999999999) && (Value <= 99999999999)){ lcd.print("0");}   
    else if ((Value > 99999999999) && (Value <= 999999999999)){ lcd.print("");}   
    else if ((Value > 999999999999) && (Value <= 9999999999999)){ lcd.print("");}   
    else {}    
  }
}


// Read and convert ASK signal
void read_fdx (void) {
  // first convert pulse durations into raw bits
    unsigned long HighTimer = 0;
    unsigned long LowTimer = 0;

    byte rawASK[maxASKBuf];
    byte multibit[maxASKBuf];
//    byte crcarray[64];
    unsigned long singlebit[150]; //128 needed

    errorbit = 0;
    CountryCode = 0;
    CardNumber = 0;
  
    int i = 0;
    int ii = 0;
    unsigned int bitcounter = 0; 
    int Hindex = 0;

//    Serial.print("\nwaiting");
    // Start - capture new data set
    while (digitalRead(inEMPin) == 0) {}  // Wait for Initial high state
    
    digitalWrite(ReadyLED, 0);
    
//    Serial.print("\nCapture Starts");
    while (i < maxASKBuf -2) {
      while (digitalRead(inEMPin) == 1) { HighTimer++;}  // increment timer while input pin is high
      rawASK[i] = HighTimer;
      HighTimer = 0;
      i++;
      
      while (digitalRead(inEMPin) == 0) { LowTimer++;}  // increment timer while input pin is low
      rawASK[i] = LowTimer;
      LowTimer = 0;
      i++;
    }
    //  Serial.print("\nCapture Ends ");

    if(debug >= 1) {
       Serial.print("\nHigh Low (starts with high: ");
       for(int i = 0; i < maxASKBuf-2; i++) {
         Serial.print((unsigned int)rawASK[i]);
         Serial.print("/");
       }
      }
    

    // Completed - capture new data set


   // biphase decode timer values
   ii = 0;
   bitcounter = 0; 
   
   while (ii < maxASKBuf -4) {
      errorbit = 0;
      Hindex = ii;

      if ((rawASK[Hindex] <= 10) || (rawASK[Hindex] >= 100)){ //<=10 to >= 100
        multibit[bitcounter] = 9;
      }

      else if (rawASK[Hindex] >= 32) { // >=40
        multibit[bitcounter] = 1;
      }

      else if ( (rawASK[Hindex] <=  35) && (rawASK[Hindex+1] <= 31) ){ // <=30 and <=30
        multibit[bitcounter] = 0;
        ii = ii + 1;
      }
      else  {multibit[bitcounter] = 9;}

    bitcounter = bitcounter + 1;
    ii = ii + 1;
    }
    //Completed Covert HighTimer into ones and LowTimer into zeros

    if(debug >= 1) {
      Serial.print("\nbits: ");
      Serial.print((unsigned int)bitcounter);
      Serial.print(" Multibit: ");
       for(int i = 0; i < bitcounter-1; i++) {
         Serial.print((unsigned int)multibit[i]);
       }
      }


// search for 11bit start header "0000 0000 00 1"
    int samecnt = 0;
    int start = -1;
    int lastv = 0;
    for(int i = 0; i < bitcounter-1; i++) {
      if(multibit[i] == lastv) {
      // inside one same bit pattern, keep scanning
        samecnt++;
      } 
      else {
      // got new bit pattern
        if(samecnt >= 10 && lastv == 0) {
        // got a start tag prefix, record index and exit
          //if (multibit[i+1] == 1) {
            start = i+1;
            break;
          //}
        }
        // either group of 0s, or fewer than 15 1s, so not a valid tag, keep scanning
        samecnt = 1;
        lastv = multibit[i];
      }  
    }
    if(debug >= 1) {
      Serial.print("\nStart: ");
      Serial.print((int)start);
    }
    // if a valid prefix tag was found, process the buffer
//       Serial.print("\nsingle : ");
    if(start >= 0 && start <= ( bitcounter - 55)) { //adjust to allow room for full dataset past start point
       int count1 = 0;
       for(int i = start; i <= start+127; i++) {
         singlebit[count1] = (unsigned long)multibit[i];
         if (singlebit[count1] >= 2) {errorbit = errorbit + 1;}
         count1 = count1+1;
       }      
//first 38 bits is id
// 1101 1000 1 0001 1101 1 1110 1000 1 0000 0000 1 0000 00  10 1 0011 0111 1 00000000 1 00000001 1 1100 1110 1 0100 1000 1 00000000100000000100000000100000000001
//           8           17          26          35        41


//       Serial.print("\nbits: ");
//       Serial.print((unsigned int)count1);
    if(debug >= 1) {
       Serial.print("\nValid ");
       for(int i =0; i <= 127; i++) {
         Serial.print(singlebit[i]);
       }
    }
 
 
 for(int i = 0, k = 0; i < 8; i++, k++) {
      CardNumber |= singlebit[i] << k;
      //crcarray[i] = singlebit[i];
    }  
   for(int i = 9, k = 8; i < 17; i++, k++) {
      CardNumber |= singlebit[i] << k;
      //crcarray[i-1] = singlebit[i];
    }  
   for(int i = 18, k = 16; i < 26; i++, k++) {
      CardNumber |= singlebit[i] << k;
      //crcarray[i-2] = singlebit[i];
    }  
   for(int i = 27, k = 24; i < 35; i++, k++) {
      CardNumber |= singlebit[i] << k;
      //crcarray[i-3] = singlebit[i];
    }  
 
   for(int i = 36, k = 0; i < 42; i++, k++) {
      CardNumberMSB |= singlebit[i] << k;
      //crcarray[i-4] = singlebit[i];
    }  
    
   for(int i = 42, k = 0; i < 44; i++, k++) {
      CountryCode |= singlebit[i] << k;
      //crcarray[i-4] = singlebit[i];
    }   
    
   for(int i = 45, k = 2; i < 53; i++, k++) {
      CountryCode |= singlebit[i] << k;
      //crcarray[i-5] = singlebit[i];      
   }     

//-----------------
/*
   for(int i = 54, k = 0; i < 62; i++, k++) {
      crcarray[i-6] = singlebit[i];      
   }     
      for(int i = 63, k = 0; i < 71; i++, k++) {
      crcarray[i-7] = singlebit[i];      
   }     

   unsigned long crcValue = 0;
   unsigned int crcCalc = 0;
   for(int i = 72, k = 0; i < 80; i++, k++) {
      crcValue |= singlebit[i] << k;
   }  
   for(int i = 81, k = 8; i < 89; i++, k++) {
      crcValue |= singlebit[i] << k;
   }  
*/

//  crcCalc = calc_crc(crcarray,63); //Calculate CRC on-the-fly   
     
//     Serial.print("\ndone detected\n");
    } 
    else {
  //    Serial.print("\ninvalid");
      errorbit = errorbit +1;}
      
    if ((CountryCode > 1) && (CardNumber > 1) && (errorbit == 0)) { 
      FDX_detected = 1;
      if(debug >= 1) {
        Serial.print("\nCC: ");
        Serial.print((unsigned long) CountryCode);  
        Serial.print("-");
        Serial.print((unsigned long) CardNumber);  
      }        
  }
    else {FDX_detected == 0;}
    digitalWrite(ReadyLED, 1);
}

void Control_Valid(int duration){
  int duration1 = 0;
  int duration2 = 0;
  duration1 = duration/4;
  duration2 = duration - duration1;
  
  digitalWrite(ReadyLED, 0);
  digitalWrite(ValidLED, 1);
  digitalWrite(ValidRelay, 1);
  delay(duration1); //typical is 2000 for 2sec

  digitalWrite(ValidRelay, 0);
  delay(duration2); //typical is 2000 for 2sec
  
  digitalWrite(ReadyLED, 1);
  digitalWrite(ValidLED, 0);
  digitalWrite(ValidRelay, 0);
}