The PCF8574P is a remote 8bit I/O expander for I2C bus with interrupt in 16 pin DIP package. It provides general purpose remote I/O expansion via two wire bidirectional I2C bus (serial clock (SCL), serial data (SDA)). The devices consist of eight quasi bidirectional ports, 100KHz I2C bus interface, three hardware address inputs and interrupt output operating between 2.5V and 6V. The quasi bidirectional port can be independently assigned as an input to monitor interrupt status or keypads or as an output to activate indicator devices such as LEDs.