[IO Expansion] PCF8574 IO Expansion Board 8-bit I/O Expander I2C-Bus Evaluation Development Module @XYGStudy 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. PCF8574, I2C interface, 8-bit parallel port