#include <LiquidCrystal.h>

/* Digital data pin and set up for LCD display */
#define data 2
#define rs 3
#define en 4
#define b4 8
#define b5 5
#define b6 11
#define b7 12
LiquidCrystal lcd(rs, en, b4, b5, b6, b7);

/* Time period of one bit of data and size of a sequence */
const uint16_t period = 10000;
const uint8_t size = 16;

/* Start and end sequence for data transfer */
//const uint16_t begin = 0b0000111111110000;
//const uint16_t end = 0b0000111100001111;
const uint16_t begin = 0b1010101010101010;
const uint16_t end = 0b0000111100001111;


/* Buffer for samples */ 
uint16_t readings; 

/* Reference time of begin of sampling */
unsigned long reference;
unsigned long sampleTime;
bool reset = true;
bool start = false;


/* Check for equality of two sequences */
bool equals(const uint16_t sequence) {
return readings == sequence;
}


/* Left rotate the buffer by n */ 
void rotate() {
  readings = (readings << 1) | (readings >> (size - 1));
}


/* Set last element of buffer with sample */
void setLSB(uint8_t sample) {
  readings |= (sample & 0x01);
}


/* Set a reference point for sampling */
void setReference() {
  volatile uint8_t* dataPort = portInputRegister(digitalPinToPort(data));
  uint8_t dataBit = digitalPinToBitMask(data);
  while ((*dataPort & dataBit) == 0) {}
  while ((*dataPort & dataBit) != 0) {}

  reset = false;
  reference = micros();
}



/* Get new sample based on known data frequancy, INPUT is inverted! */
uint8_t getSample() {
  uint8_t sample;
  sampleTime = reference + (period >> 1);
  while (micros() < sampleTime)  {}
  sample = digitalRead(data);
  reference += period;
  return (sample ^ 0x01);
}


/* Wait for begin sequence and fill buffer with samples */
uint8_t getSequence() {
  if (reset)
    setReference();

  while (!start) {
    if (equals(begin))
      start = true;
    rotate();
    setLSB(getSample());
  }

  for (uint8_t i = 0; i < size; i++) {
    rotate();
    setLSB(getSample());
  }
  Serial.println(readings, BIN);
  return readings;
}


/* Decode a modulated sequence */
uint8_t decodeManchester(uint16_t encoded) {
  uint8_t decoded = 0;
  if ((encoded >> size - 2) == 0x0001)
    return 0x24;

  for (uint8_t i = 0; i < (size >> 1); i++) {
    uint8_t maskedLSB = encoded & 0x03;

    if (encoded & 0x0001)
      decoded |= (1 << i);
    encoded >>= 2;

    if (maskedLSB == 0x03 || maskedLSB == 0x00)
      return 0x25;
  }
  return decoded;
}


/* Create a string from given characters */
char* createString() {
  char message[size + 1];
  for (uint8_t i = 0; i < size; i++) {
    char c = decodeManchester(getSequence());
    message[i] = c;
  }
  message[size + 1] = '\0';
  return message;
}




void setPWM() {
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);

  TCNT1 = 0;
  TCCR1A = 0;
  TCCR1B = 0;

  TCCR1B |= _BV(CS12) | _BV(CS10);        // Set prescaler to 1024
  ICR1 = 156;                            // Output frequency = CLK frequency / (prescaling factor * ICR1), TNCNT1 = TOP

  OCR1A = 78;                           // Duty cycle = (ICR1 - OCR1A) / ICR1), corresponds to Arduino Nano output 9 
  TCCR1A |= _BV(COM1A1) | _BV(COM1A0);        

  OCR1B = 78;                            // Duty cycle = OCR1B / ICR1, corresponds to Arduino Nano output 10
  TCCR1A |= _BV(COM1B1);

  TCCR1B |= _BV(WGM13);
  TCCR1A |= _BV(WGM11);
}


void setup() {
  // put your setup code here, to run once:
  delay(2000);
  Serial.begin(9600);
  lcd.begin(16,2);
  lcd.clear();
  lcd.setCursor(0,0); 

  setPWM();

}

unsigned long startTime;
unsigned long difference;


void loop() {
  // startTime = micros();
  // for (int i = 0; i < 5; i++) {
  //   char decoded = decodeManchester(encoded[i]);
  //   str[i] = decoded;
  //   Serial.print(decoded);
  //   }
  // Serial.println();
 
  lcd.print(createString());





}