/**
*@breif the BH1750 driver and test demo
*/


#include <stdio.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <errno.h>


//#define I2C_ADDR 0x5c
#define I2C_ADDR 0X23    //the BH1750 device i2c address

/**
@breif  main for get light 
*/
int main(void)
{
        int fd = 0;
        char buf[3] = {0,};
        char val = 0;
    char value = 0;
        float flight = 0.0;

/*open the devices for light sensor*/
        fd=open("/dev/i2c-2",O_RDWR);
        if(fd<0)
        {
                printf("err open file:%s\r\n",strerror(errno)); 
        return 1;
        }

/*set the I2C slave device address*/
        if(ioctl( fd,I2C_SLAVE,I2C_ADDR)<0 )
        {
                printf("ioctl error : %s\r\n",strerror(errno));return 1;
        }


/*config the BH1750 */
        val=0x01;
        if(write(fd,&val,1)<0)
        {
                printf("write 0x01 err\r\n");
        }
/*config the BH1750 */
        val=0x10;
        if(write(fd,&val,1)<0)
        {
                printf("write 0x10 err\r\n");
        }

/*loop to read the light value */
        while(1)
        {
                if(read(fd,&buf,3))  /*read the light value from bh1750*/
                {
                        flight=(buf[0]*256+buf[1])/1.2; /*calculate the real light power*/
                        printf("The current light is %6.3f lx\r\n",flight);
                }
                else
                {
                        printf("read light error\r\n");
                }
                usleep(100000);//sleep 0.1s
        }
}