/*******************************************

 * Description: Read temperature sensor from LM75

 * Author:        Aaron.gao

 * Data:        20170524

 * Histroy:

 *                1. NULL

 * ****************************************/

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <linux/i2c-dev.h>

#include <stdlib.h>

#include <fcntl.h>

#include <termios.h>

/* main func */

int main(int argc, char **argv)

{

    int ret, fd;

    char buffer[];

    int value;

    float temp = 0.0;

    while()

    {

        /* open device */

        fd = open("/sys/bus/i2c/devices/i2c-1/1-004f/hwmon/hwmon0/temp1_input", O_RDONLY);

        if( fd < )

        {

            printf("fd is %d\r\n", fd);

            printf("open i2c device-lm75 failed!\r\n");

            exit();

        }

        ret = read(fd, buffer, );

        if(ret < )

        {

            printf("read error\r\n");

        }

        value = atoi(buffer);

        memset(buffer, , strlen(buffer));

        temp = value / 1000.0;

        printf("environment temperature is %.2lfC\r\n", temp);

        sleep();

        close(fd);

    }

    return ;

}