Hi ich bekomme immer 0x80 zurückgeschickt.

weiss nicht mehr weiter hier mein code.

Code:
unsigned char read_pcf8591(unsigned char adc)
{
	unsigned char ret;
	unsigned char byte = 0;

	ret = i2c_start(pcf8591_address+I2C_WRITE);  // Sende Start Condition
	if(ret!=0)
	{
		i2c_stop();
		uart_puts("Io1f");
		return 0;
	}
	
	ret = i2c_write(0);                // Senden des Control Bytes startet die A/D Wandlung
	i2c_stop();                            // Sende Stop Condition, Bus freigeben*/
	delay_ms(1);                             // Warten bis A/D Wandlung benedet (mind. 90µs)
	
	ret = i2c_start(pcf8591_address+I2C_READ);  // Sende Start Condition

	// Mehrmaliges Lesen um alte A/D Werte zu ignorieren
	byte = i2c_readAck();      // Lese Byte + no acknowledge*/
	byte = 	i2c_readNak();      // Lese Byte + no acknowledge*/
	
	i2c_stop();                           // Sende Stop Condition, Bus freigeben
	return byte;
}
Danke