This module is designed specifically for expand for the GPIO of the Banana Pi a which can effectively solve the banana send IO port insufficient. It use PCF8574 chip to expand 8 Bidirectional IO. The module connection to the Banana Pi through I2C bus. There are 8 I2C address in the module and user can choose one of them through setup the “ADDR” jumper. User also can choose 5V or 3.3V electric level. Module with isolation protection, can effectively prevent external high voltage damage to the Banana Pi. Multiple module can cascade.