/*
 * Master Firmware: I2C
 *
 * Wireless Observational Modular Aerial Network
 * 
 * Ethan Zonca
 * Matthew Kanning
 * Kyle Ripperger
 * Matthew Kroening
 *
 */

#ifndef I2C_H_
#define I2C_H_

#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
#endif

#include <avr/io.h>


/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */
#define I2C_READ    1
/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */
#define I2C_WRITE   0


void i2c_init(void);	//initialize the I2C master interace. Need to be called only once
void i2c_stop(void);	//Terminates the data transfer and releases the I2C bus

unsigned char i2c_start(unsigned char addr);	//Issues a start condition and sends address and transfer direction 
	//addr is the address and transfer direction of I2C device
	//Returns   0   device accessible 
	//Returns   1   failed to access device 

unsigned char i2c_rep_start(unsigned char addr);	//Issues a repeated start condition and sends address and transfer direction
	//addr is the address and transfer direction of I2C device
	//Returns   0   device accessible
	//Returns   1   failed to access device
	
void i2c_start_wait(unsigned char addr);	//Issues a start condition and sends address and transfer direction. If device is busy, use ack polling to wait until device ready 
	//addr is the address and transfer direction of I2C device

unsigned char i2c_writeX(unsigned char data);	//Send one byte to I2C device
	//data is the byte to be transfered
	//Returns   0   write successful
	//Returns   1   write failed

unsigned char i2c_readAck(void);	//read one byte from the I2C device, request more data from device
	//Returns byte read from I2C device

unsigned char i2c_readNak(void);	//read one byte from the I2C device, read is followed by a stop condition
	//Returns byte read from I2C device

unsigned char i2c_readX(unsigned char ack);	//read one byte from the I2C device. Implemented as a macro, which calls either i2c_readAck or i2c_readNak
#define i2c_readX(ack)  (ack) ? i2c_readAck() : i2c_readNak(); 
	//When ack is 1: send ack, request more data from device
	//When ack is 0: send nak, read is followed by a stop condition
	//Returns byte read from I2C device

void i2c_write(unsigned char addr, unsigned char reg, unsigned char data); //Does complete write. Can be used as stand alone function.

unsigned char i2c_read(unsigned char addr, unsigned char reg);

#endif /* I2C_H_ */