#define D_IN DDRC&=~(1<<PC4)	// DDR Data In
#define D_OUT DDRC|=(1<<PC4)	// DDR Data Out
#define D_H PORTC|=(1<<PC4)	// Data High
#define D_L PORTC&=~(1<<PC4)	// Data Low
#define C_H PORTC|=(1<<PC5)	// CLK High
#define C_L PORTC&=~(1<<PC5)	// CLK Low
#define D_P PINC&(1<<PC4)	// Abfrage Data

unsigned char i2c_out(unsigned char data) {
	int del = 100, i;
	D_OUT;
	D_L;
	_delay_us(del);

	for (i = 0; i < 8; i++) {
		C_L;
		if (data & (1<<(7-i))) {
			D_H;
		}else {
			D_L;
		}
		_delay_us(del);
		C_H;
		_delay_us(del);

	}
	C_L;
	D_IN;
	_delay_us(del);
	C_H;
	//if (D_P) return 0;

	_delay_us(del);
	C_L;
	_delay_us(del);
	return 1;
}

In der main:


		i2c_out(0x49);
		D_OUT;
		C_H;
		_delay_us(100);
		D_H;