One minute self introduction: I am an I/O expansion module based on I2C interface control, which can expand up to 16 I/O ports and support the simultaneous use of up to 8 expansion modules for a total of 128 I/O ports. It is compatible with 3.3V and 5V level I2C interface control. Only 2 signal lines are needed to expand 16 I/O ports. The I2C communication address can be set by shorting the A0/A1/A2 solder joints. It provides two interface types: PH2.0 terminal and solder pad, and supports parallel connection of multiple I2C modules. Onboard level conversion circuit allows compatibility with 3.3V and 5V operating levels. Working voltage: 5V / 3.3V Control interface: I2C Product size: 38mm x 23mm Via diameter: 2.0mm Color: As shown Material: PC Due to different product batches, the appearance may vary slightly, but this does not affect usage. Package Contents: 1 x Expansion Module, 1 x Cable Only the items listed are included; other products are not included. Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement error allowance is +/- 1-3cm.