GPIO Expander Bonnet - 16 Additional I/O over I2C

Raspberry Pi Bonnet adding 16 digital I/O pins via I2C. Pins are configurable as outputs (high/low) or inputs with optional internal pull-ups, grouped into two 16-pin connectors with ground.

Logical pinout · physical placement not verified

GPA0-GPA7
Header A exposes eight MCP23017 GPIO pins; the Learn pinouts page says the bottom row numbered 0-7 is the 8 IO pins.
Type · Signal
GPB0-GPB7
Header B exposes eight MCP23017 GPIO pins; the Learn pinouts page says the bottom row numbered 0-7 is the 8 IO pins.
Type · Signal
GND headers
The Learn pinouts page states the top row of each GPIO header is ground.
Type · Ground
STEMMA QT
On-board STEMMA QT connector for I2C plug-and-play peripherals on the Bonnet.
Type · SignalVoltage · I2C logic level shifted from Raspberry Pi 3V logic; Bonnet GPIO side defaults to 5V per Learn page.
INTA
MCP23017 interrupt output pin exposed on the Bonnet for GPIO change notification.
Type · Signal
INTB
MCP23017 interrupt output pin exposed on the Bonnet for GPIO change notification.
Type · Signal
3V5V jumper
Jumper selects the expander GPIO logic rail; Learn page states the Bonnet defaults to 5V and can be changed to 3V.
Type · PowerVoltage · Default 5V, selectable 3V

Pin	Type	Function	Voltage
GPA0-GPA7	Signal	Header A exposes eight MCP23017 GPIO pins; the Learn pinouts page says the bottom row numbered 0-7 is the 8 IO pins.
GPB0-GPB7	Signal	Header B exposes eight MCP23017 GPIO pins; the Learn pinouts page says the bottom row numbered 0-7 is the 8 IO pins.
GND headers	Ground	The Learn pinouts page states the top row of each GPIO header is ground.
STEMMA QT	Signal	On-board STEMMA QT connector for I2C plug-and-play peripherals on the Bonnet.	I2C logic level shifted from Raspberry Pi 3V logic; Bonnet GPIO side defaults to 5V per Learn page.
INTA	Signal	MCP23017 interrupt output pin exposed on the Bonnet for GPIO change notification.
INTB	Signal	MCP23017 interrupt output pin exposed on the Bonnet for GPIO change notification.
3V5V jumper	Power	Jumper selects the expander GPIO logic rail; Learn page states the Bonnet defaults to 5V and can be changed to 3V.	Default 5V, selectable 3V

Logical pinout · physical placement not verified

Pin details

7 connections

GPA0-GPA7
Header A exposes eight MCP23017 GPIO pins; the Learn pinouts page says the bottom row numbered 0-7 is the 8 IO pins.
Signal
GPB0-GPB7
Header B exposes eight MCP23017 GPIO pins; the Learn pinouts page says the bottom row numbered 0-7 is the 8 IO pins.
Signal
GND headers
The Learn pinouts page states the top row of each GPIO header is ground.
Ground
STEMMA QT
On-board STEMMA QT connector for I2C plug-and-play peripherals on the Bonnet.
SignalVoltage · I2C logic level shifted from Raspberry Pi 3V logic; Bonnet GPIO side defaults to 5V per Learn page.
INTA
MCP23017 interrupt output pin exposed on the Bonnet for GPIO change notification.
Signal
INTB
MCP23017 interrupt output pin exposed on the Bonnet for GPIO change notification.
Signal
3V5V jumper
Jumper selects the expander GPIO logic rail; Learn page states the Bonnet defaults to 5V and can be changed to 3V.
PowerVoltage · Default 5V, selectable 3V

Start wiring

Shield

Confirm the data interface matches your host board.

Module pins: 3V/5V jumper, GND headers, GPA0-GPA7, GPB0-GPB7, STEMMA QT, INTA, INTB. Schematik maps them to your board in the app.

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