This simple little Logic Level Converter will let you easily interface 5v and 3.3v devices. With this board you can step up a 3.3v signal to 5v, or down from 5 to 3.3. This is great when you need to connect 5v sensors/microcontrollers to ARM based devices like the Arduino Due or Raspberry Pi. You can even solder standard headers to this board to make it breadboard compatible.
The level converter is very easy to use. The board needs to be powered from the two voltages sources (high voltage and low voltage) that your system is using. High voltage (5V for example) to the 'HV' pin, low voltage (2.8V for example) to 'LV', and ground from the system to the 'GND' pin.
Pins are labeled as Inputs and Outputs. These are relative to the board. A digital one going into the RXI pin on the 5V side will show up on the RXO pin on the 3.3V side as 3.3V. A digital one going into the TXI pin on the 3.3V side will show up on the TXO pin on the 5V side as 5V.
Each board comes with 2 channels, giving you a total of 2 high-to low ports and 2 low-to-high ports. The TX lines are bi-directional while the RX lines are not.