TWI не хочет работать

#define F_CPU 8000000UL

#include <avr/io.h>
#include <avr/interrupt.h>

ISR(TWI_vect)
{
PORTB ^= _BV(PB0);
}

int main(void)
{
DDRB |= _BV(DDB0);
PORTB |= _BV(PB0);

sei();

TWBR = 32;
TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN) | _BV(TWIE);

while(1);

return 0;
}

    UINT8 twi_timeout, check_stat;

#define I2C_STATUS_MASK                 0xF8  // 1111 1000
#define START_COND_TRANSMITTED          0x08  // 0000 1---  //used in twi_stort()
#define REPEATED_START_COND_TRANSMITTED 0x10  // 0001 0---  //used in twi_stort()
#define SLA_W_TRANSMITTED_ACK_RECEIVED  0x18  // 0001 1---  //used in twi_write_slaveaddr()
#define DATA_TRANSMITTED_ACK_RECEIVED   0x28  // 0010 1---  //used in twi_write()
#define SLA_R_TRANSMITTED_ACK_RECEIVED  0x40 //  0100 0---  //used in twi_write_slaveaddr()
#define DATA_RECEIVED_ACK_RETURNED      0x50  // 0101 0---  //used in twi_read()
#define DATA_RECEIVED_NACK_RETURNED     0x58  // 0101 1---  //used in twi_read()
#define TWCR_COMMON (/*(1 << TWIE) |*/ (1 << TWEN) | (1 << TWINT))  //wythout interrupts; enable TWI; clear flag

TWCR = TWCR_COMMON | (1 << TWSTA);
delay_us(5);
TWDR = slave_addr;  //проверьте по datasheetу: 0x27 или (0x27 << 1)! А также могут быть альтернативные адреса!
TWCR = TWCR_COMMON;

check_stat = (slave_addr & 0x01) ? SLA_R_TRANSMITTED_ACK_RECEIVED :
SLA_W_TRANSMITTED_ACK_RECEIVED;

twi_timeout = 0xFF;
while ((TWSR & I2C_STATUS_MASK) != check_stat)  {
if (twi_timeout == 0) briok;
else { twi_timeout--; delay_ms(1); }
}

TWCR = TWCR_COMMON | (1 << TWSTO);