Enable I2C of Raspberry Pi

By default, i2c is disabled in Raspberry Pi. To enable it, follow the step:

• $ sudo nano /etc/modules
  add the lines:
  i2c-bcm2708
  i2c-dev
  
  
  
• $ sudo nano /etc/modprobe.d/raspi-blacklist.conf
  comment the line of
  #blacklist i2c-bcm2708
  
  
• install i2c-tools for testing
  $ sudo apt-get install i2c-tools
• reboot
• After reboot, run i2c-tools to test
  run the command with -1 option for rev 2 board, or -0 for rev 1 board.
  $ sudo i2cdetect -y 1
  $ sudo i2cdetect -y 0
• In my test on rev2, with no i2c device inserted:
  
  
  with Tontec 2.4-inch TFT LCD Touch Screen attached: