AtTiny2313 <-> FoxBoard G20 mit I2C

I2C_WriteToDevice(i2c_fd, 0x02, 0x00);

void I2C_WriteToDevice(int fd, int reg, int val) {

    char buf[2];

    buf[0] = reg; //Register

    buf[1] = val; //Wert

    if (write(fd, buf, 2) != 2) {

        printf("Schreiben fehlgeschlagen...\n");

        return(0);

    }

}

i2c_buffer[0] = 3;

i2c_buffer[1] = 6;

i2c_buffer[2] = 40;

i2c_buffer[3] = 50;

i2c_buffer[4] = 152;

I2C_WriteToDevice();

//------------

void I2C_WriteToDevice(void) {

    if (write(i2c_fd, i2c_buffer, sizeof(i2c_buffer)) != sizeof(i2c_buffer)) {

        printf("Schreiben fehlgeschlagen...\n");

        return(0);

    }

}

/****************************************************/

/* The USI as Slave                                 */

/* Author: Axel Gartner                             */

/****************************************************/

#define  F_CPU 1000000UL

#include <util/delay.h>

#include <avr/io.h>

#include <avr/interrupt.h>

#define USI_DATA         USIDR

#define USI_STATUS      USISR

#define USI_CONTROL     USICR

#define USI_ADDRESS      0x20

#define NONE        0

#define ACK_PR_RX      1

#define BYTE_RX        2

#define ACK_PR_TX      3

#define PR_ACK_TX      4

#define BYTE_TX        5

// Device dependant defines

/*#if defined(__at90tiny26__) | defined(__attiny26__)

#define DDR_USI             DDRB

#define PORT_USI            PORTB

#define PIN_USI             PINB

#define PORT_USI_SDA        PORTB0

#define PORT_USI_SCL        PORTB2

#endif*/

#if defined(__AVR_ATtiny2313A__)

#define DDR_USI             DDRB

#define PORT_USI            PORTB

#define PIN_USI             PINB

#define PORT_USI_SDA        PORTB5

#define PORT_USI_SCL        PORTB7

#endif

volatile uint8_t COMM_STATUS = NONE;

//uint8_t tmp1[2];

void USI_init(void) {

  // 2-wire mode; Hold SCL on start and overflow; ext. clock

  USI_CONTROL |= (1<<USIWM1) | (1<<USICS1);

  USI_STATUS = 0xf0;  // write 1 to clear flags, clear counter

  DDR_USI  &= ~(1<<PORT_USI_SDA);

  PORT_USI &= ~(1<<PORT_USI_SDA);

  DDR_USI  |=  (1<<PORT_USI_SCL);

  PORT_USI |=  (1<<PORT_USI_SCL);

  // startcondition interrupt enable

  USI_CONTROL |= (1<<USISIE);

}

int main(void) {

  USI_init();

  sei();

  for(;;)  {

  }

}

SIGNAL(USI_START_vect ) {

  uint8_t tmpUSI_STATUS;

  tmpUSI_STATUS = USI_STATUS;

  COMM_STATUS = NONE;

  // Wait for SCL to go low to ensure the "Start Condition" has completed.

  // otherwise the counter will count the transition

  while ( (PIN_USI & (1<<PORT_USI_SCL)) );

  USI_STATUS = 0xf0; // write 1 to clear flags; clear counter

  // enable USI interrupt on overflow; SCL goes low on overflow

  USI_CONTROL |= (1<<USIOIE) | (1<<USIWM0);

}

SIGNAL(USI_OVERFLOW_vect ) {

  uint8_t BUF_USI_DATA = USI_DATA;

  switch(COMM_STATUS) {

    case NONE:

      if (((BUF_USI_DATA & 0xfe) >> 1) != USI_ADDRESS) {  // if not receiving my address

        // disable USI interrupt on overflow; disable SCL low on overflow

        USI_CONTROL &= ~((1<<USIOIE) | (1<<USIWM0));

      }

      else { // else address is mine

        DDR_USI  |=  (1<<PORT_USI_SDA);

        USI_STATUS = 0x0e;  // reload counter for ACK, (SCL) high and back low

        if (BUF_USI_DATA & 0x01) COMM_STATUS = ACK_PR_TX; else COMM_STATUS = ACK_PR_RX;

      }

    break;

    case ACK_PR_RX:

      DDR_USI  &= ~(1<<PORT_USI_SDA);

      COMM_STATUS = BYTE_RX;

    break;

    case BYTE_RX:

      /* Save received byte here! ... = USI_DATA */

      if (USI_DATA == 6) {

        PORTD |= (1<<PD3);

        _delay_ms(1000);

        PORTD &= ~(1<<PD3);

      }

      DDR_USI  |=  (1<<PORT_USI_SDA);

      USI_STATUS = 0x0e;  // reload counter for ACK, (SCL) high and back low

      COMM_STATUS = ACK_PR_RX;

    break;

    case ACK_PR_TX:

      /* Put first byte to transmit in buffer here! USI_DATA = ... */

      PORT_USI |=  (1<<PORT_USI_SDA); // transparent for shifting data out

      COMM_STATUS = BYTE_TX;

    break;

    case PR_ACK_TX:

    if(BUF_USI_DATA & 0x01) {

      COMM_STATUS = NONE; // no ACK from master --> no more bytes to send

    }

    else {

      /* Put next byte to transmit in buffer here! USI_DATA = ... */

      PORT_USI |=  (1<<PORT_USI_SDA); // transparent for shifting data out

      DDR_USI  |=  (1<<PORT_USI_SDA);

      COMM_STATUS = BYTE_TX;

    }

    break;

    case BYTE_TX:

      DDR_USI  &= ~(1<<PORT_USI_SDA);

      PORT_USI &= ~(1<<PORT_USI_SDA);

      USI_STATUS = 0x0e;  // reload counter for ACK, (SCL) high and back low

      COMM_STATUS = PR_ACK_TX;

    break;

  }

  USI_STATUS |= (1<<USIOIF); // clear overflowinterruptflag, this also releases SCL

}

      for (uint8_t i=0; i<5; i++) {

        tmp1[i] = USI_DATA;

      }