PCF8575 module expansion IO port board is a compact IO expander that provides 16 quasi bidirectional I/O ports over I2C. It is powered from a DC supply in the 2.5 to 5.5 V range and includes an I2C speed switch for flexible bus timing. The board ships as 1 piece per package. Key benefits Increases available I/O without using multiple MCU pins: add 16 I/O ports through a single I2C device. Simplifies hardware wiring: expand I/O on a single I2C bus, reducing pin routing on your main controller. Flexible power and bus settings: supports DC 2.5–5.5 V operation and includes an I2C speed switch to adapt to different systems. Easy to integrate with common MCUs and development platforms: designed for use with I2Ccapable microcontrollers and single board computers. Key attributes Functionality: PCF8575 based module providing 16 I/O ports expandability via I2C. Compatibility: suitable for microcontrollers and single board computers that support I2C communication. Voltage and power: operates from DC power in the 2.5–5.5 V range. Interface: I2C communication with an onboard I2C speed switch. Port count: 16 ports available on the module for expansion. Packaging: supplied as 1 piece per package (1PCS). Two to three use cases Microcontroller I/O expansion: add 16 digital outputs or inputs to an Arduino, ESP32, or similar MCU project to drive LEDs, read digital sensors, or interface with simple relays. Home automation and control panels: use the 16 ports to monitor or switch devices such as lights, relays, or sensors on a single I2C bus, reducing wiring complexity. Prototyping and electronics experiments: quick expansion of available GPIOs for testing logic, sequencing, or interfacing multiple digital peripherals without reworking the main controller's pinout. Usage notes Connect power and ground to the DC supply within the stated 2.5–5.5 V range. Connect the I2C signals (SDA and SCL) to the corresponding I2C pins on your controller. Use the I2C speed switch to select the desired bus speed, then communicate with the PCF8575 over I2C to read or write the 16 I/O ports. This module is intended to expand I/O in a wide range of electronics projects while remaining easy to integrate with existing I2Cenabled systems.