{"title":"Adafruit GPIO Expander Bonnet - 16 Additional I/O over I2C","handle":"adafruit-gpio-expander-bonnet-16-additional-i-o-over-i2c","url":"/products/adafruit-gpio-expander-bonnet-16-additional-i-o-over-i2c","description":"The Adafruit GPIO Expander Bonnet adds 16 extra digital I/O pins to your Raspberry Pi over I²C. Based on the MCP23017 chip, it plugs directly onto the Pi's 40-pin header and communicates via SDA/SCL, leaving your other GPIO pins free. Each pin can be configured as a digital output (up to 20 mA per pin) or as an input with optional internal pull-up resistors.\n\nBy default, the expander runs at 5V logic (with level-shifted I²C at 3.3V), making it suitable for driving white, blue, or green LEDs that may not work reliably at 3.3V. A solder jumper lets you switch to 3.3V logic if needed. With address select jumpers, you can stack up to 8 bonnets on a single Pi for a total of 128 additional GPIO pins.\n\nKey Features\n\n\n16 Extra Digital I/O Pins – Grouped into two 16-pin connectors, each with a matching ground pin\n\nMCP23017 I²C GPIO Expander – Controlled via SDA/SCL, no extra GPIO pins consumed\n\nOutput: Up to 20 mA Per Pin – Drive LEDs directly (recommended total under 125 mA for the chip)\n\nInput with Internal Pull-Ups – Connect buttons and switches without extra resistors\n\nInterrupt Support – INTA and INTB pins available for solder connections to detect GPIO changes\n\n5V or 3.3V Logic – Default 5V logic with solder jumper option for 3.3V\n\nStackable – Address select jumpers (0x20–0x27) allow up to 8 bonnets for 128 GPIO total\n\nCircuitPython Support – Python 3 library for quick setup and configuration\n\n\nIdeal For\n\nRaspberry Pi projects needing more digital I/O pins\nLED control arrays and indicator panels\nButton matrix and switch input expansion\nMulti-sensor and multi-actuator setups\n\n\nPackage Contents\n\n1× Adafruit GPIO Expander Bonnet – Assembled and tested with slim 2×20 header\n2× 16-pin IDC sockets (unsoldered, for optional installation)\n\n\n\nNote: Raspberry Pi not included. The bonnet is designed for Raspberry Pi models with a 40-pin GPIO header.\n\n\nResources\n\nAdafruit GPIO Expander Bonnet Learn Guide\nCircuitPython MCP230xx Library (GitHub)\n","vendor":"Adafruit","product_type":"physical","in_stock":true,"options":[],"variants":[{"id":6939,"title":"Default Title","sku":"AF-4132","price":20.71,"on_sale":false,"in_stock":true,"available_quantity":2,"option1":"Default Title"}]}