Logic Level Converter
The logic level converter is a small device that safely steps down 5V signals to 3.3V and steps up 3.3V to 5V. Each level converter has the capability of converting 4 pins on the high side to 4 pins on the low side. Two inputs and two outputs are provided for each side.
Can be used with normal serial, I2C, SPI, and any other digital signal. Does not work with an analog signal.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 (3.3V for example) to 'LV'.
[Logic Level Convertor schematic]