USART im SPI Mode, keinen Takt

void SPI_USART_Init()

{

  UBRR0 = 0;

  // Setting the XCKn port pin as output, enables master mode. 

  DDRD |= _BV(PD4);

  // Set MSPI mode of operation and SPI data mode 

  UCSR0C = (1<<UMSEL01)|(1<<UMSEL00)|(1<<UCPHA0)|(1<<UCPOL0);

  // Enable receiver and transmitter. 

  UCSR0B = (1<<RXEN0)|(1<<TXEN0);

  // Set baud rate. 

  // IMPORTANT: The Baud Rate must be set after the transmitter is enabled 

  UBRR0 = 6;

}

unsigned int SPI2_MasterTransfer (unsigned int c1)

{

  while (!(UCSR0A & (1<<UDRE0))){ asm volatile("nop"); };

  UCSR0A |= (1 << TXC0);

  UDR0 = c1;

  while (!(UCSR0A & (1<<RXC0)));  

  return UDR0;

  _delay_ms(100);

}