#define F_CPU 16000000UL // Defining the CPU Frequency

#include <avr/io.h>      // Contains all the I/O Register Macros
#include <util/delay.h>  // Generates a Blocking Delay

#define USART_BAUDRATE 9600 // Desired Baud Rate
#define BAUD_PRESCALER (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)

#define ASYNCHRONOUS (0<<UMSEL00) // USART Mode Selection

#define DISABLED    (0<<UPM00)
#define EVEN_PARITY (2<<UPM00)
#define ODD_PARITY  (3<<UPM00)
#define PARITY_MODE  DISABLED // USART Parity Bit Selection

#define ONE_BIT (0<<USBS0)
#define TWO_BIT (1<<USBS0)
#define STOP_BIT ONE_BIT      // USART Stop Bit Selection

#define FIVE_BIT  (0<<UCSZ00)
#define SIX_BIT   (1<<UCSZ00)
#define SEVEN_BIT (2<<UCSZ00)
#define EIGHT_BIT (3<<UCSZ00)
#define DATA_BIT   EIGHT_BIT  // USART Data Bit Selection


#define RX_COMPLETE_INTERRUPT         (1<<RXCIE0)
#define DATA_REGISTER_EMPTY_INTERRUPT (1<<UDRIE0)

volatile uint8_t GlobalTransmit;

// uint8_t GlobalTransmit;
static uint8_t j=0;

//volatile int GlobalTransmit;

void USART_Init()
{
	// Set Baud Rate
	UBRR0H = BAUD_PRESCALER >> 8;
	UBRR0L = BAUD_PRESCALER;
	
	// Set Frame Format
	UCSR0C = ASYNCHRONOUS | PARITY_MODE | STOP_BIT | DATA_BIT;
	
	// Enable Receiver and Transmitter
	UCSR0B = (1<<RXEN0) | (1<<TXEN0);

	sei();    //Enabling Global Interrupt
}

void UART_transmit_interrupt(char *data)
{

	  while(*data!='\0')
		{
    GlobalTransmit=data[j];
		UCSR0B |= DATA_REGISTER_EMPTY_INTERRUPT; // Enables the Interrupt
		}
		
}

void USART_TransmitPolling(char * DataByte)
{
	uint8_t i;
  while(*DataByte!='\0')
	{
	while (( UCSR0A & (1<<UDRE0)) == 0) {}; // Do nothing until UDR is ready
	UDR0 = DataByte[i];
	DataByte++;

	}
}



void setup()
 {
  USART_Init();
		USART_TransmitPolling("Treel");
	UCSR0B |= RX_COMPLETE_INTERRUPT;
}

void loop()
 {
    //uint8_t LocalData[15]="TreelPvtltd\n";
    // UART_transmit_interrupt(LocalData);
  	
}

ISR(USART_UDRE_vect)
{
	  
		UDR0 =GlobalTransmit;
		j++;
		if(GlobalTransmit=='\0'){j=0;}
	  UCSR0B &= ~DATA_REGISTER_EMPTY_INTERRUPT; // Disables the Interrupt, uncomment for one time transmission of data
}

ISR(USART_RX_vect)
{
	GlobalTransmit= UDR0;
	UDR0 = GlobalTransmit;
}




 /* In this program,
    @Receiver side
    >Treel is sent to enable serial monitor
		>We write some text on Serial monitor console
		> data is received in UDR0(storage buffer of UART), we write 1 to RXC0 bit, after receiving is 
		  complete RXC0 bit is cleared after recepetion complete.
			Till reception is not completed one byte data(i.e is only one character) is stored in UDR0 buffer
		>We copy this one byte data in a user created pointer data.
		>Pointer data stores in itself the actual data and the actual data is returned to the address of buffer(local_data) indicated in main program.
    
		>One-One byte data is received in buffer(local_data)indicated in main program.
		 how the receiving data is stored in next array without we incrementing the array it is unknown to me
		>We are copying the buffer data(local_data) to other buffer(buffer_data).(This step of our prcatice)



		@Transmitter side
		>We writing to serial monitor by using the 	USART_TransmitPolling function, we are passing buffer base address(buffer_data).
		>In USART_TransmitPolling function we have pointer which points to the address of buffer(buffer_data) and picking up the actual data.
		>Data byte by byte is passed to UART Buffer(UDR0) while it is cleared  and while the string we are passing reaches till '/0'.*/