#include <avr/io.h>
#include <util/delay.h>

#define F_CPU 16000000UL
#define baud 9600
#define ubrr ((F_CPU / (baud * 16UL)) - 1)

void uart_init(void)
{
  UBRR0H = (ubrr >> 8);
  UBRR0L = ubrr;
  UCSR0B |= (1 << RXEN0) | (1 << TXEN0);
  UCSR0C |= (1 << UCSZ01) | (1 << UCSZ00);
}

void data_transmit(unsigned char data)
{
  while(!(UCSR0A & (1 << UDRE0)));
  UDR0 = data;
}

unsigned char data_recieve(void)
{
  while(!(UCSR0A & (1 << RXC0)));
  return UDR0;
}

void send_data(unsigned char *string)
{
  while(*string != '\0')
  {
    data_transmit(*string++);
  }
}

void flush_data(void)
{
  while(UCSR0A & (1 << RXC0))
  {
    volatile unsigned char dummy = UDR0;
    (void)dummy;
  }
}

int main(void)
{
  uart_init();
  DDRD |= (1 << PD2);
  PORTD &= ~(1 << PD2);
  while(1)
  {
    unsigned char temp = data_recieve();
    data_transmit(temp);

    if(temp == '1')
    {
      PORTD |= (1 << PD2);
      data_transmit('\r');
      data_transmit('\n');
      send_data("led turned on");
    }
    else if(temp == '0')
    {
      PORTD &= ~(1 << PD2);
      data_transmit('\r');
      data_transmit('\n');
      send_data("led turned off");
    }
    data_transmit('\r');
    data_transmit('\n');
  }
  return 0;
}