TWI will nicht so wie ich wohl will

[Ceos]

situation: 2 mega8
10k pullup
100kHz sollten eingestellt sein

start condition klappt, address klappt ... nur das databyte haut einfach net hin, da bleiben se hängen, bitte um hilfe

master

void TWI_Init_Master(void)
{
	cli();
	TWI_RCount = 0;
	TWI_WCount = 0;
	TWBR = 32;
	TWSR &= ~(BV(TWPS0)|BV(TWPS1));
	TWSR |= BV(TWPS0);
	TWCR = BV(TWEN);
	sei();
}

bool TWI_SendByte(unsigned char target, unsigned char data )
{
	char b[3];
	PORTB = BV(PB1);
	TWCR |= BV(TWINT)|BV(TWSTA);
	while(!(TWCR & BV(TWINT)));
	if (TW_STATUS != TW_START) {
		PORTB |= BV(PB2);
		itoa(TW_STATUS, b, 16);
		USART_Transmit(b[0]);
		USART_Transmit(b[1]);
		TWI_ERROR;
		return false;
	}
	TWDR = (target | TW_WRITE);
	TWCR |= BV(TWINT);
	while (!(TWCR & BV(TWINT)));
	if (TW_STATUS != TW_MT_SLA_ACK) {
		PORTB |= BV(PB3);
		itoa(TW_STATUS, b, 16);
		USART_Transmit(b[0]);
		USART_Transmit(b[1]);
		TWI_ERROR;
		return false;
	}
	TWDR = data;
	TWCR |= BV(TWINT);
	while (!(TWCR & BV(TWINT)));
	if (TW_STATUS != TW_MT_DATA_ACK) {
		PORTB |= BV(PB4);  
		itoa(TW_STATUS, b, 16);
		USART_Transmit(b[0]);
		USART_Transmit(b[1]);
		TWI_ERROR; // <------ steigt aus mit TW_STATUS 0x10
		return false;
	}
	TWCR |= BV(TWINT)|BV(TWSTO);
	PORTB = 0;
	return true;
}

slave

void TWI_Init_Slave(unsigned char addr) //Even Addr. does not respond to general call
{
	cli();
	TWAR = addr;
	TWI_RCount = 0;
	TWI_WCount = 0;
	TWBR = 32;
	TWSR &= ~(BV(TWPS0)|BV(TWPS1));
	TWSR |= BV(TWPS0);
	TWCR = BV(TWEN)|BV(TWIE)|BV(TWEA);
	sei();
}

SIGNAL(SIG_2WIRE_SERIAL)
{
	char b[3];
	PORTB = BV(PB0);
	if (TW_STATUS != TW_SR_SLA_ACK) {
		PORTB |= BV(PB1);
		itoa(TW_STATUS, b, 16);
		USART_Transmit(b[0]);
		USART_Transmit(b[1]);
		TWCR |= BV(TWEA)|BV(TWINT);
		while(1);
		return;
	}
	TWCR |= BV(TWEA)|BV(TWINT);
	while(!(TWCR & BV(TWINT)));
	if (TW_STATUS != TW_SR_DATA_ACK) {
		PORTB |= BV(PB2);
		itoa(TW_STATUS, b, 16);
		USART_Transmit(b[0]);
		USART_Transmit(b[1]);  <---- steigt aus mit 0xA0
		while(1);   
  		return;
	}
	TWI_ringbuff[TWI_WCount] = TWDR;
	TWI_WCount++;
	TWCR |= BV(TWEA)|BV(TWINT);
	while(!(TWCR & BV(TWINT)));
	if (TW_STATUS != TW_SR_STOP) {
		PORTB |= BV(PB3);
		itoa(TW_STATUS, b, 16);
		USART_Transmit(b[0]);
		USART_Transmit(b[1]);
		TWCR |= BV(TWEA)|BV(TWINT);
		while(1);
		return;
	}
	PORTB = 0;
	TWCR |= BV(TWEA)|BV(TWINT);
}