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'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.