Re: [Gumstix-users] I2C 8-Bit Address Issue

[batoub <ba...@gm...>]

Big thanks !!!!

It's working now :)

I try to read the result now with this : ( registre 2, size 16bits )
    uint8_t dataByte[ I2C_MAX_DATA_LEN ];
    int gByteCount=2;
    uint8_t addr=2;
    I2cReadBytes( i2cDev, addr, dataByte, gByteCount );

But I have to convert the result for hexa to dec with this :
    sprintf(str,"%x",dataByte[0]);
    distancecm=255*strtoul(str, NULL, 16);
    sprintf(str,"%x",dataByte[1]);
    distancecm=distancecm+strtoul(str, NULL, 16);
    printf("Distance en cm : %u \n",distancecm);

It's seem to be a bit stranger because the max value that i can found is
60cm. Have you got an other solution ??

Thank for your help !

2008/4/23 Dave Hylands <dhy...@gm...>:

> Hi,
>
> >  I have a problem with SRF08 sonar, I try to change the address of mine
> using
> >  this code :
> >
> >  #define chgtaddresse1          0xA0
> >  #define chgtaddresse2          0xAA
> >  #define chgtaddresse3          0xA5
> >  #define chgtaddresse4          0xF2
> >
> >         gI2cAddr = 0x74;
> >
> >
> >         if (( i2cDev = open( i2cDevName, O_RDWR )) < 0 )
> >         {
> >                 LogError( "Error  opening '%s': %s\n", i2cDevName,
> strerror( errno ));
> >                 exit( 1 );
> >         }
> >         I2cSetSlaveAddress( i2cDev, gI2cAddr, I2C_USE_CRC );
>
> The SRF08 sonar device doesn't use CRC's. So pass I2C_NO_CRC instead.
>
> >         I2cTransfer( i2cDev, chgtaddresse1, NULL, 0, NULL, 0, NULL );
> >         close( i2cDev );
>
> Why are you closing and reopening? Just leave the file descriptor open.
>
> You're also sending the wrong data. The SRF08 datasheet says that you
> need to send a 4 seperate commands to register 0. What you're doing is
> sending no data to register A0 and then no data to register AA, etc.
>
> So you should be doing something like:
>
> I2cWriteByte( i2cDev, 0, 0xA0 );
> I2cWriteByte( i2cDev, 0, 0xAA );
> I2cWriteByte( i2cDev, 0, 0xA5 );
> I2cWriteByte( i2cDev, 0, 0xF2 );
>
> --
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
>
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