Hi, [USING : Ubuntu 12.04 LTS] I am trying to learn I2C subsystem. I havent found much of well documented things that can help a newbie on google. I just chose to read the linux kernel documentation txts. I read the way kernel can interact with i2c through both SMBus calls & raw file op calls (ioctl, read, write). It looks good till that point. The doc also tells about i2c stub. which can be used as follows: 1. load the i2c module 2. use i2cset (from the i2c-tools project) to pre-load some data 3. load the target chip driver module 4. observe its behavior in the kernel log I was able to achieve just the 1st step here. I loaded the module successfully. $ sudo modprobe i2c-stub chip_addr=0x023 I got following Kern msg $dmesg ... [658.071706] i2c-stub: Virtual chip at 0x23 So I believe that step 1 is clear. in second step I have no idea how to provide needed inputs to command -> Usage : i2cset [-f] [-y] [-m mask] I2CBUS CHIP-ADDRESS DATA-ADDRESS [VALUE] [MODE] I tried to give I2CBUS = 0, Chip addr = 0x23 & data addr=0 but it gives error Error : Could not open file '/dev/i2c-0' or '/dev/i2c/0' : No such file or directory There is no file at all created in /dev corrosponding to this device. Any idea how to use i2c properly? Is this an ubuntu only problem? Can anybody provide a good tutorial like thing to learn about i2c kernel & userspace driver programming? -- Thanks and Regards, Sagar