Adafruit PCF8575 GPIO EXPANDER BREAKOUT STEMMA QT I2C

Adafruit PCF8575 GPIO Expander Breakout

The Adafruit PCF8575 GPIO Expander is an affordable I2C breakout that adds 16 extra GPIO pins for projects where onboard pins are insufficient. It enables easy control of buttons, LEDs, and peripherals with just two I2C pins. Multiple expanders can be chained, up to 8 per bus, providing 64 total GPIOs.

The PCF8575 works differently from the MCP230xx series:

• Low-cost and easy to use
• 16 I/O pins
• 3 address select jumpers allow up to 8 expanders per bus
• Pins can be used as light pull-up inputs or strong ground outputs
• IRQ output automatically signals input changes
• No pin direction register – pin mode depends on its driven state

There are two operating modes:

• Light pull-up input: default logic high, pulled low when connected to ground.
• Strong ground output: pin is forced low, useful for sinking current to drive LEDs or signals.

For example, buttons can be read by wiring between a PCF pin and ground, while LEDs can be controlled by pulling the pin low. Arduino and CircuitPython/Python libraries simplify usage by abstracting the unusual pin behavior.

The breakout is designed in the STEMMA QT form factor, compatible with SparkFun Qwiic connectors. This makes it easy to interface without soldering and to daisy-chain with other I2C devices.

Product Dimensions:

• Size: 40.8 mm x 17.7 mm x 4.5 mm
• Weight: 2.6 g

Packaging includes:

• Adafruit PCF8575 GPIO -laajennuskortti
• Piikkirima

Links:

• Product information page
• PCF8575 Datasheet (PDF)