/********************************************************************************
                                Includes
********************************************************************************/
#include <avr/io.h>
#include <stdio.h>
#include <stdbool.h>

/********************************************************************************
                                Macros and Defines
********************************************************************************/
#define BAUD 19200
#define MYUBRR F_CPU/16/BAUD-1

/********************************************************************************
                                Function Prototypes
********************************************************************************/
void usart_init(uint16_t ubrr);
char usart_getchar( void ); 
void usart_putchar( char data ); 
void usart_pstr(char *s);
unsigned char kbhit(void);

/********************************************************************************
                                Main
********************************************************************************/
int main( void )
{
     // configure PORTA as output
    DDRA = 0xFF;
	// setup PORTB data direction as an input
	DDRB = 0;
	// make sure it is high impedance and will not source
	PORTB = 0;

	// fire up the usart
	usart_init ( MYUBRR );

	// dump some strings to the screen at power on
	usart_pstr("Ready to rock and roll!\n\r");
	usart_pstr("Type in a character, and I will transpose it up by 1:\n\r");
	
	// main loop
	while(true) {
		// if a key has been pressed, then process it
		if(kbhit()) {
			usart_putchar(usart_getchar() + 1);
		}
		
		// map the PINB inputs to the PORTA outputs
		PORTA = PINB;

		// a little humor is always good, PB0 gets the user yelled at
		if(bit_is_clear(PINB,PB0)) {
			usart_pstr("OUCH! Stop poking me!\n\r");
		}
	}
	return 0;
}

/********************************************************************************
                                usart Related
********************************************************************************/
void usart_init( uint16_t ubrr) {
	// Set baud rate
	UBRRH = (uint8_t)(ubrr>>8);
	UBRRL = (uint8_t)ubrr;
	// Enable receiver and transmitter
	UCSRB = (1<<RXEN)|(1<<TXEN);
	// Set frame format: 8data, 1stop bit
	UCSRC = (1<<URSEL)|(3<<UCSZ0);
}

void usart_putchar(char data) { 
	// Wait for empty transmit buffer
	while ( !(UCSRA & (_BV(UDRE))) );
	// Start transmission
	UDR = data; 
}

char usart_getchar(void) { 
	// Wait for incomming data
	while ( !(UCSRA & (_BV(RXC))) );
	// Return the data
	return UDR;
} 

void usart_pstr(char *s) {
    // loop through entire string
	while (*s) {  
        usart_putchar(*s);
        s++;
    }
}

unsigned char kbhit(void) {
	//return nonzero if char waiting  polled version
	unsigned char b;
	b=0;
	if(UCSRA & (1<<RXC)) b=1;
	return b;
}