Problem mit SPI zwischen Atmega8 und Attiny2313

#define F_CPU 1000000UL // 1 MHz

#define DDR_SPI  DDRB

#define PORT_SPI PORTB

#define DD_MOSI  DDB3

#define DD_MISO  DDB4

#define DD_SCK   DDB5

#define DD_SS    DDB0

#define LED      DDD5

#include <avr/io.h>

#include <util/delay.h>

#include <avr/interrupt.h>

#define ACK 0x7E

//Initialize SPI Master Device

void spi_init_master (void)

{

  DDR_SPI = (1<<DD_SCK)|(1<<DD_MOSI); //Set MOSI, SCK as Output

  PORT_SPI = (1<<DD_MISO); // Set pull ups

  SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0); //Enable SPI, Set as Master

}

//Function to send and receive data

unsigned char spi_tranceiver (unsigned char data)

{

  SPDR = data; //Load data into the buffer

  while(!(SPSR & (1<<SPIF) )); //Wait until transmission complete

  return(SPDR); //Return received data

}

int main(void)

{

  spi_init_master(); //Initialize SPI Master

  DDRD |= 0x01; //PD0 as Output

  unsigned char data; //Received data stored here

  while(1)

  {

    data = 0x00; //Reset ACK in "data"

    data = spi_tranceiver('0'); //Send "0", receive ACK

    _delay_ms(500);

    data = 0x00;

    data = spi_tranceiver('1'); //Send "1", receive ACK

    _delay_ms(500);

  }

}

#define F_CPU 1000000UL // 1 MHz

#include <avr/io.h>

#include <avr/interrupt.h>

#include <util/delay.h>

#define DDR_SPI  DDRB

#define PORT_SPI PORTB

#define DD_MOSI  DDB5  //DI

#define DD_MISO  DDB6  //DO

#define DD_SCK   DDB7

#define DD_SS    DDB4

#define LED      DDD5

#define ACK 0x7E

void spi_init_slave (void)

{

  DDR_SPI |= (1<<DD_MISO); // MISO output

  DDR_SPI &= ~(1<<DD_SCK)|~(1<<DD_MOSI); // SCK and MOSI input

  PORT_SPI = (1<<DD_SCK)|(1<<DD_MOSI); // Set pull ups

  USICR = (1<<USIWM0)|(1<<USICS1); // Enable USI as SPI Slave

}

unsigned char spi_tranceiver (unsigned char data)

{

  USIDR = data;

  while(!(USISR&(1<<USIOIF)));

  return(USIDR);

}

int main(void)

{

   DDRD = (1<<LED);

  spi_init_slave(); //Initialize slave SPI

  unsigned char data;

  while(1)

  {

    data = spi_tranceiver(ACK); //Receive data, send ACK

    if (data == '0')

    {

      //set port PD5 HIGH

      PORTD &= ~(1<<LED);

      _delay_ms(100);

    }

    if (data == '1')

    {

      //set port PD5 LOW

      PORTD |= (1<<LED);

      _delay_ms(100);

    }

    _delay_ms(20);

  }

}