AVR Freaks

void spiTest()
{
   spiInit();

   PORTB |= 1<<2;          // Set SS high
   spiTransferByte (0x8f); // Select Control Register of DS1305
   spiTransferByte (0x00); // Enable osc, enable write, disable alarms 
   PORTB &= ~(1<<2);       // Set SS low

// read write test
   PORTB |= 1<<2;          // Set SS high
   spiTransferByte (0xA0); //  empty data space
   spiTransferByte (0xff); // set to 255
   PORTB &= ~(1<<2);       // Set SS low
  
   PORTB |= 1<<2;       
   spiTransferByte(0x20);    // read address corresponds to A0 write addres
   rprintf("output= %d \r\n", spiTransferByte(0x00));
   PORTB &= ~(1<<2);
}
void spiInit()
{
    // setup SPI I/O pins
    sbi(PORTB, 5);  // set SCK hi
    sbi(DDRB, 5);   // set SCK as output
    cbi(DDRB, 4);   // set MISO as input
    sbi(DDRB, 3);   // set MOSI as output
    sbi(DDRB, 2);   // SS must be output for Master mode to work
	
	// setup SPI interface :
	// master mode
	sbi(SPCR, MSTR);
   
   // clock speed = Fosc/16
	cbi(SPCR, SPR0);
	sbi(SPCR, SPR1);

	// select clock phase positive-going in middle of data
	cbi(SPCR, CPOL);
        sbi(SPCR, CPHA); 

	// Data order MSB first
	cbi(SPCR,DORD);

	// enable SPI
	sbi(SPCR, SPE);
		
	// clear status
	inb(SPSR);
	spiTransferComplete = TRUE;
}
u08 spiTransferByte(u08 data)
{
	// send the given data
	spiTransferComplete = FALSE;
	outb(SPDR, data);

		while(!(inb(SPSR) & (1<<SPIF)));

		// set flag
		spiTransferComplete = TRUE;

	// return the received data
	return inb(SPDR);
}