#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>


#define I2C_BUS "/dev/i2c-3"


int I2C_Write(int address, int value) {

	struct i2c_smbus_ioctl_data argswrite;

        argswrite.read_write = I2C_SMBUS_WRITE;
        argswrite.size = I2C_SMBUS_BYTE;
        argswrite.data = NULL;		
	argswrite.command = value;

	int device = open(I2C_BUS, O_RDWR);

	if (device == -1) return device;

	ioctl(device, I2C_SLAVE, address);
	ioctl(device, I2C_SMBUS, &argswrite);	

	close(device);
}


int I2C_Read(int address) {

	union i2c_smbus_data data;
        struct i2c_smbus_ioctl_data argsread;
        
        argsread.read_write = I2C_SMBUS_READ;
        argsread.size = I2C_SMBUS_BYTE;
        argsread.data = &data;
        argsread.command = 0;

        int device = open(I2C_BUS, O_RDWR);

        if (device == -1) return device;

        ioctl(device, I2C_SLAVE, address);
        ioctl(device, I2C_SMBUS, &argsread);              

        close(device);

	return data.byte;
}