1pcs PCF8575 Module Expansion 16 IO port Expander board I2C GPIO Port Expander

PCF8575 I/O Expander Module Description 

Running out of I/O pins for your project? This high-performance module solves the problem by expanding up to 16 additional I/O pins—all controlled via just two I/O pins! Powered by the PCF8575 chip, it relies on the I2C communication interface and features 16-bit quasi-bidirectional input/output pins, making it a compact and efficient solution for I/O expansion needs. 

Core Hardware Design 

Onboard 3.3V Level Shifter Circuit 

The module’s logic level is flexibly adjustable via the VCC-VDD solder pad, adapting to different MCU voltage requirements: 

- If the VCC-VDD solder pad is unconnected, the PCF8575 operates at 3.3V logic levels (compatible with 3.3V MCUs like ESP32, Raspberry Pi Pico). 

- If the VCC-VDD solder pad is soldered, the logic level will match the VCC supply voltage (supports 5V MCUs like Arduino UNO R3). 

Key Features 

- Arduino-Friendly Compatibility: Works with the dedicated `PCF8575` library, enabling quick code integration and development. 

- Flexible Power Supply: Supports an operating voltage range of 2.5V–5.5V DC, compatible with most mainstream MCU power systems. 

- Stable Current Capacity: Total maximum current for all 16 pins is 100mA, meeting the power needs of common peripherals. 

- Adjustable I2C Address: 

- Default I2C address: 0x20. 

- Address can be modified by soldering the A1 & A2 address selection pads—supports multiple modules on the same I2C bus (avoids address conflicts for large-scale expansion). 

- 16 Independent I/O Pins: Each pin can be individually configured as input or output, adapting to diverse control and sensing scenarios. 

- Interrupt Output Function: Equipped with an open-drain interrupt output pin, which triggers when the input state of the module changes (reduces MCU polling frequency and saves resources). 

Typical Applications 

- MCU Compatibility: Ideal for Arduino UNO R3, ESP32, ESP8266, STM32, Raspberry Pi Pico, and other microcontrollers with I2C interfaces. 

- Peripheral Control: Perfect for connecting and controlling relays, buzzers, buttons, LEDs, small motors, and other simple electronic components—expands the functionality of basic MCUs without I/O pin limitations.