#include <Arduino.h>

// filepath: /c:/IHC Linnaleiri 29A1/IHCNANO/src/main.cpp
#define MODULE_PIN 2 // Define the pin connected to the relay module
#define CONTROL_PORT PORTD // Define the port of the control pin

// Define delay values in microseconds
#define DELAY_START_HIGH 4100*2
#define DELAY_START_LOW 300*2
#define DELAY_D150 150*2
#define DELAY_D300 300*2
#define DELAY_D600 600*2

#define SET_PORT_BIT(port, bit, value) \
  if (value) { \
    port |= (1 << bit); \
  } else { \
    port &= ~(1 << bit); \
  }

enum State {
  START_HIGH,
  START_LOW,
  D150,
  D300,
  D600
};

volatile State currentState = START_HIGH;
volatile uint16_t data = 0x1234; // Example data to send
volatile int bitIndex = 0;

void setup() {
  pinMode(MODULE_PIN, OUTPUT);
  SET_PORT_BIT(CONTROL_PORT,MODULE_PIN, HIGH); // Ensure relay is HIGH during START_HIGH state

  // Configure Timer1
  cli(); // Disable interrupts
  TCCR1A = 0;               // Clear Timer1 control register A
  TCCR1B = 0;               // Clear Timer1 control register B
  TCNT1 = 0;                // Initialize counter value to 0
  // Set up Timer1 for 1us resolution
  cli(); // Disable interrupts

  // Set Timer1 to CTC mode
  TCCR1B |= (1 << WGM12);

  // Set the prescaler to 8
  TCCR1B |= (1 << CS11);

  // Enable Timer1 compare match A interrupt
  TIMSK1 |= (1 << OCIE1A);

  // Set initial compare value for the first interval (S4100)
  OCR1A = DELAY_START_HIGH; // Set compare match register for 4.1 ms
  sei(); // Enable interrupts

}

ISR(TIMER1_COMPA_vect) {
  static uint8_t parity = 0;
  static uint8_t bitNumber = 0;
  bool bit = 0;
  switch (currentState) {
    case START_HIGH:
      // Transition to START_LOW state
      SET_PORT_BIT(CONTROL_PORT,MODULE_PIN, LOW); // Set output LOW when exiting START_HIGH
      currentState = START_LOW;
      OCR1A = DELAY_START_LOW; // Set compare match register for 300 us
      break;
    
    case START_LOW:
      // Transition to D150 or D300 state
      SET_PORT_BIT(CONTROL_PORT,MODULE_PIN, HIGH); // Set output HIGH when exiting START_LOW
      currentState = D150;
      OCR1A = DELAY_D150; // Set compare match register for 150 us
      break;

    case D150:
      // Transition to D600 state
      if (bitNumber < 16) {
        bit = (data >> bitNumber) & 1;
        parity ^= bit;    
      }
      else {
        bit = parity;
      }
      SET_PORT_BIT(CONTROL_PORT,MODULE_PIN, !bit); 
      currentState = D300;
      OCR1A = DELAY_D300 - DELAY_D150; // Set compare match register for 150 us
      break;
    
    case D300:
      // Transition to D600 state
      SET_PORT_BIT(CONTROL_PORT,MODULE_PIN, LOW); // Set output LOW when exiting D300
      currentState = D600;
      OCR1A = DELAY_D600 - DELAY_D300; // Set compare match register for 300 us
      break;
    
    case D600:
      // Transition to D150 or D300 state, or START_HIGH if all bits processed
      bitNumber++;
      SET_PORT_BIT(CONTROL_PORT,MODULE_PIN, HIGH); // Set output HIGH when exiting D600
      if (bitNumber < 17) {
          currentState = D150;
          OCR1A = DELAY_D150; // Set compare match register for 150 us
        } else {
          currentState = START_HIGH;
          OCR1A = DELAY_START_HIGH; // Set compare match register for 4.1 ms
          bitNumber = 0;
          parity = 0;
        }
      
      break;
  }
}

void loop() {
  // Main loop does nothing, all work is done in ISR
}