By Jose
DFrobot IIC TO GPIO module  is 3.3V compatible as well as 5V.

This makes the module a suitable option for IO expander and sensor connector board.
With most V2 sensors upgraded and enabled support to 3.3V. A nice range of sensor's are available to use.

In order to use this on a Raspbian image, you will need to do the following steps:
  1. enable I2C module, by commenting out on/etc/modprobe.d/raspi-blacklist.conf
  2. Add the module to the kernel on this file /etc/modules by adding "i2c-dev" 
  3. apt-get update and install  i2c-tools and "adduser pi i2c"
This is a brief starting list, if anyone needs help feel free to ask how to do it.

Install the required modules:
modprobe i2c-bcm2708 ( required? )
modprobe i2c-dev

Afterwards, just wire the board to I2C bus and 3.3V pin. NOT the 5V as you would on Arduino.

run the following command and you should get the module detected:
i2cdetect -y 1

Play with the following commands:

To read the first 8 inputs
i2cset -y 1 0x20 0x00
i2cget -y 1 0x20

To read the next 8 inputs
i2cset -y 1 0x20 0x01
i2cget -y 1 0x20

To set the first 8 bits to be outputs
i2cset -y 1 0x20 0x06 0x00
And to turn all the outputs on
i2cset -y 1 0x20 0x02 0xff