working i2c connection to RSBS2-card

[rsbs2] / bmc / i2c.c

#include <util/twi.h>
#include <avr/interrupt.h>
#include <stdio.h>
#include "i2c.h"

#define TWCR_ACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);  
#define TWCR_NACK TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|(0<<TWWC);
#define TWCR_RESET TWCR = (1<<TWEN)|(1<<TWIE)|(1<<TWINT)|(1<<TWEA)|(0<<TWSTA)|(1<<TWSTO)|(0<<TWWC);  

void i2c_init()
{
	TWAR = BMC_ADDR & 0xfe;
	TWDR = 0x00;
	TWCR &= ~((1<<TWSTA) | (1<<TWSTO));
	TWCR |= ((1<<TWEA) | (1<<TWEN) | (1<<TWIE)); 
	printf("Status: 0x%02x\n", TW_STATUS);
	PORTC = 0x03;
}

ISR (TWI_vect, ISR_BLOCK)
{
	printf("Interrupt, Status: 0x%02x, Data: 0x%02x!\n", TW_STATUS, TWDR);

	switch (TW_STATUS) {
		default:
			TWCR_ACK;
			break;
	}
}