The PCF8574 IO Expansion Board is used as remote 8-bit I/O expander for I2C-bus. Up to 8 PCF8574, IO Expansion Board can be connected to the I2C-bus, providing up to 64 I/O ports. The PCF8574 IO Expansion Board features I2C pin header on one side and I2C connector on the opposite side. Hence, it #39;s more flexible to connect the board to your development system. The board also supports I2C cascading, allowing the use of a multi-module connected to the I2C bus at the same time by connecting the pin header and connector. Features: Working voltage: 2.5-6V Interface: IIC 8-bit parallel port