////////////////////////////// main.c  ///////////////////////////////////////
#define F_CPU 1843200
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdlib.h>
#include <util/delay.h>


unsigned char __edge, __bitcount;

void uart_putc(unsigned char c);
void decode(unsigned char sc);
void uart_init (void);
void keyboard_init(void);
void clr(void);

int main (void)
{ 

	keyboard_init();
	uart_init();
	uart_putc('\x0c');
	sei();
	while (1)
	{
	}
	return 0;
}

void uart_init(void)
{
	#ifndef F_CPU
	#warning "F_CPU war noch nicht definiert, wird nun nachgeholt mit 4000000"
	#define F_CPU 4000000UL  
	#endif
 
	#define BAUD 9600UL
 
	#define UBRR_VAL ((F_CPU+BAUD*8)/(BAUD*16)-1)   
	#define BAUD_REAL (F_CPU/(16*(UBRR_VAL+1)))     
	#define BAUD_ERROR ((BAUD_REAL*1000)/BAUD) 
 
	#if ((BAUD_ERROR<990) || (BAUD_ERROR>1010))
	#error Systematischer Fehler der Baudrate grösser 1% und damit zu hoch! 
	#endif
	UCSRB |= (1<<TXEN)|(1<<RXEN);  
	UCSRC |= (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);  
 
	UBRRH = UBRR_VAL >> 8;
	UBRRL = UBRR_VAL & 0xFF;
}

void uart_putc(unsigned char c)
{
    while (!(UCSRA & (1<<UDRE)))  /* warten bis Senden moeglich */
    {
    }                             
    UDR = c;                      /* sende Zeichen */
    return; 
}

void keyboard_init(void)
{
	MCUCR=2;
	GIMSK=(1<<INT0);
	GIFR=(1<<INTF0);
	__edge=0;
	__bitcount=11;
}

ISR(INT0_vect)
{
    static unsigned char data;                // Holds the received scan code

    if (!__edge)                                // Routine entered at falling edge
    {
        if(__bitcount < 11 && __bitcount > 2)    // Bit 3 to 10 is data. Parity bit,
        {                                    // start and stop bits are ignored.
            data = (data >> 1);
            if(PINA & 4)
                data = data | 0x80;            // Store a '1'
        }

        MCUCR = 3;                            // Set interrupt on rising edge
        __edge = 1;
        
    } else {                                // Routine entered at rising edge

        MCUCR = 2;                            // Set interrupt on falling edge
        __edge = 0;

        if(--__bitcount == 0)                    // All bits received
        {
			decode(data);
            __bitcount = 11;
        }
    }
	return;
}

void decode ( unsigned char sc )
{
	static unsigned char set_release ; 

//		if ( ! set_release )
//		{
			if ( sc != 240 )		// scancode not 0xF0 at release of key
			{
				uart_putc(sc); 		// put scancode to display
			} else {
//				set_release = 1;		// scancode match 0xF0
			}
//		} else {
//			set_release = 0;			// this decode call echo nothing on display
//		}
	return;
} 

void clr(void)
{
	uart_putc(0x0c);
}

#################### Makefile ###########################


PROJECT = main
SOURCES = main.c
CC = avr-gcc
OBJCOPY = avr-objcopy

PORT = /dev/ttyU0

MMCU = atmega32

CFLAGS = -mmcu=$(MMCU) -Wall -Os


default: $(SOURCES)
		$(CC) $(CFLAGS) -I./ -o $(PROJECT).out $(SOURCES)
		$(OBJCOPY) -j .text -O ihex $(PROJECT).out $(PROJECT).hex

install:
		sudo avrdude -e -p m32 -P $(PORT) -c stk500v2 -U flash:w:$(PROJECT).hex
fuse:
		sudo avrdude -e -p m32 -P $(PORT) -c stk500v2 -U lfuse:w:0xff:m -U hfuse:w:0xd9:m
clean:
		rm -fP $(PROJECT).out
		rm -fP $(PROJECT).hex