Features: 1Compatibility Level: Changes in the state of an input port can generate an interrupt output (INT). On board level conversion circuit, compatible with 3.3V/5V working level. 2Support 4 Expansion Modules: I2C communication address can be set, short circuit AO, A1 solder joint can modify the communication address, support the use of 4 expansion modules. 3I2C Interface Control: I2C interface control, only 2 signal lines are needed to expand 16 I/O ports. 4Current Controllable: The Extension module supports 16 channel common anode constant current ED drive, 256 step linear dimming, and current controllable. 5Two Interface Types: The I2C interface expand board provides two interface types, PH2.0 terminal and pad, and supports parallel connection of multiple I2C modules. Package included: 1 x IO&nbspExpansion&nbspBoard 1 x For Dupont Wire