//Drehgeber
/////////////////////////////////////////////////////////////////////////////////////////////////////////
#define XTAL        8e6         // 8MHz

#include <interrupt.h>
#include <stdint.h> // this is needed for int8_t, etc.


                // target: ATmega328
                //------------------------------------------------------------------------


                #define PHASE_A     (PIND & 1<<2) // PORTB pin 1 MODIFY TO SUIT YOUR NEEDS
                #define PHASE_B     (PIND & 1<<3) // PORTB pin 3 MODIFY TO SUIT YOUR NEEDS

                //#define LEDS_DDR    DDRC
                //#define LEDS        PORTC           // LEDs against VCC


                volatile int8_t enc_delta;          // -128 ... 127
                static int8_t last;




	void encode_init( void )
	{
		int8_t new;

		

		new = 0;
		if( PHASE_A ) new = 3;
		if( PHASE_B ) new ^= 1;       // convert gray to binary
		last = new;                   // power on state
		enc_delta = 0;

		DDRD.3=1;
		PORTD.3=1;
		DDRD.2=1;
		PORTD.2=1;

		
		// *********************************************************************
		// Timer/Counter 0 initialization BY THE WIZARD
		// Clock source: System Clock
		// Clock value: 250.000 kHz
		// Mode: CTC top=OCR0A
		// OC0A output: Disconnected
		// OC0B output: Disconnected
		// Timer Period: 1 ms @ 8MHz?
		TCCR0A=(0<<COM0A1) | (0<<COM0A0) | (0<<COM0B1) | (0<<COM0B0) | (1<<WGM01) | (0<<WGM00);
		TCCR0B=(0<<WGM02) | (0<<CS02) | (1<<CS01) | (1<<CS00);
		TCNT0=0x00;
		OCR0A=0xF9;
		OCR0B=0x00;
		// Timer/Counter 0 Interrupt(s) initialization
		TIMSK0=(0<<OCIE0B) | (1<<OCIE0A) | (0<<TOIE0);
		//************************************************************************
	}


ISR( TIM0_COMPA )            // 1ms for manual movement
{
	int8_t new, diff;

	new = 0;
	if( PHASE_A ) new = 3;
	if( PHASE_B ) new ^= 1;          // convert gray to binary
	diff = last - new;               // difference last - new
	if( diff & 1 ) {                 // bit 0 = value (1)
		last = new;                    // store new as next last
		enc_delta += (diff & 2) - 1;   // bit 1 = direction (+/-)
	}
}




int8_t encode_read1( void )         // read single step encoders
{
	int8_t val;

	cli();
	val = enc_delta;
	enc_delta = 0;
	sei();
	//printf("ENCODE1: %lu\n", val);
	//delay_ms(200);
	return val;                   // counts since last call
}


int8_t encode_read2( void )         // read two step encoders
{
	int8_t val;

	cli();
	val = enc_delta;
	enc_delta = val & 1;
	sei();
	//printf("ENCODE2: %lu\n", val);
	//delay_ms(200);
	return val >> 1;
}


/////////////////////////////////////////////////