Adafruit PCF8574 I2C GPIO Expander Breakout - STEMMA QT / Qwiic

Expand your project possibilities with the Adafruit PCF8574 GPIO Expander Breakout - an affordable 8 channel I2C expander designed for easy integration with STEMMA QT/Qwiic systems.

This GPIO expander is perfect when you need more GPIO pins for buttons, LEDs, or other peripherals but don't want to upgrade to a larger development board. It connects via I2C, sharing the bus with other sensors and devices, allowing easy and cost-effective expansion of your input/output capabilities.

Key Features:

• Affordable 8 channel I2C GPIO expander
• Three I2C address select jumpers allowing up to 8 expanders on one bus (64 GPIO total)
• Each pin can act as input with light pull-up or output sink (20mA low-driving transistor)
• IRQ output alerts when input pins change state
• Open-drain output with built-in 100K pull-up resistor for each pin
• Compatible with Adafruit's Arduino and CircuitPython PCF8574 libraries for easy programming
• Custom PCB in STEMMA QT form factor for easy, solderless connections
• Dimensions: 25.5mm x 17.7mm x 4.6mm
• Weight: 1.7 grams

Notes: Pin direction is handled uniquely as either a lightly pulled input or a strong ground output. This behavior is ideal for controlling LEDs and reading button states with simple wiring configurations.

STEMMA QT connectors on both sides are compatible with SparkFun Qwiic system, enabling daisy-chaining of multiple sensors and devices with compatible cables (cables not included).