IO Pi Plus

32 channel MCP23017 digital I/O expander for the Raspberry Pi

£14.39 each (excluding VAT: £11.99)
50 available
Product Code: IOPi Plus 2.1
EAN: 7426787870149
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  •  32 GPIO pins
  • Control via the Raspberry Pi I2C port
  • Python, MicroPython, Home Assistant, C, C++, Node.js and .Net Core software libraries
  • Stack up to 4 IO Pi Plus boards on a single Raspberry Pi
  • Solder jumper selectable I2C addresses
  • External 5V Input with an isolation solder jumper
  • Based on the MCP23017 from Microchip Technologies Inc
  • Configurable interrupt output pins - Configurable as active-high, active-low or open-drain
  • Polarity Inversion register to configure the polarity of the input port data

The IO Pi Plus is an expansion module designed to enhance your Raspberry Pi and other similar single-board computers with an additional 32 GPIO pins*. This expansion is powered by two MCP23017 16-bit I/O expanders from Microchip, enabling the addition of up to 32 digital connections to your Raspberry Pi setup.

This module can draw power directly from the Raspberry Pi through the 40-pin GPIO connector or from an external power source. It also features extended GPIO pins, allowing for the stacking of multiple IO Pi Plus boards alongside other expansion modules.

The onboard solder jumpers for I2C address selection make it highly flexible; each MCP23017 expander can be set to one of 8 addresses, permitting the use of up to 4 IO Pi Plus boards together, thereby extending the total GPIO availability to 128 pins. This capacity can be further increased by integrating our I2C Switch expansion board.

For those requiring a separate high-current power source, the IO Pi Plus provides a 5V port that can be isolated from the Raspberry Pi with a solder jumper marked "Link" on the board, alleviating the power demand on the Raspberry Pi. This feature is particularly useful when multiple IO Pi Plus boards are connected. Compatible with our 5mm screw terminals for the 5V input.

For external operation from the Raspberry Pi, connections for 3.3V (Pin 1), SDA (Pin 3), SCL (Pin 5), Ground (Pin 6), and the 5V pin (if not using an external power supply) must be made from the Raspberry Pi GPIO header to the corresponding pins on the IO Pi Plus.

How to use:

If you have any questions on how to use the IO Pi Plus you can browse through our Frequently Asked Questions.

Our Knowledge Base has a series of step-by-step guides that will guide you through setting up and using your IO Pi Plus.

We have a Support Forum where you can post questions and find answers.

* Microchip recommends that pin 8 (GPA7) and pin 16 (GPB7) are used as outputs only.  This change was made for revision D MCP23017 chips manufactured after June 2020. See the MCP23017 datasheet for more information.

Legacy IO Pi Versions

See our KB article for previous versions of this board.

Technical Details

Input Ratings & Specifications

Vdd (5V pin on I2C bus)
2.7V - 5.5V
All digital inputs and outputs:
0 - Vdd
Current at I/O Pin (sourced or sunk):
25 mA
Maximum current on a single I/O Bank (1 MCP23017 device):
125 mA

3D CAD Model

Click to downloadIO Pi Plus - 3D CAD File (STEP Format)


Click to View
View the schematic PDF.

Mechanical Drawings

Mechanical Drawing

Click the image to enlarge.


We have tested the IO Pi Plus on the following platforms.

Model Status
Raspberry Pi Pico series
Raspberry Pi Model A / B
Raspberry Pi 1 Model A+ / B+
Raspberry Pi 2 Model B
Raspberry Pi 3 Model A+ / B / B+
Raspberry Pi 4 Model B
Raspberry Pi 5
Raspberry Pi Zero
Raspberry Pi Zero W / Zero 2 W
Raspberry Pi Compute Module 4 IO Board
Raspberry Pi 400
Orange Pi
Asus Tinker Board

Code Libraries and Demos

This expansion board has Python, MicroPython, C, C++, Node.JS, .Net Core, Arduino and Home Assistant libraries available to get you started with your next project.  You can download all of the libraries from GitHub at: or click on the logos below for your selected programming language.

Assembly Instructions

The IO Pi Plus is supplied with the 40-pin GPIO connector unsoldered. Before using the IO Pi Plus, you need to solder the connector onto the PCB. The power link and I2C address selection are configured using solder jumpers. For convenience, we supply the IO Pi Plus with the power link jumper and one address selection jumper pre-soldered.

The I/O input pads are spaced 2.54mm apart. You can solder wires directly to the board or use 2.54mm pitch headers. The IO Pi Plus is compatible with 20-pin IDC vertical and right-angle headers allowing you to use ribbon cables to connect your external devices to the board.

To install the IO Pi, press the 40-pin connector down onto the Raspberry Pi GPIO pins with the board sitting over the top of the Raspberry Pi.

When installing more than one IO Pi on a single Raspberry Pi board, you must configure the address select jumpers for each IO Pi.

Remove the isolation jumper when connecting an external power supply to the 5V port.

Assembly Guide Video

Watch our assembly guide on YouTube. (opens in a new window)

PCB Header Assembly Jig

Download and print our PCB Header Assembly Jig to hold your circuit board when soldering the header pins.


I2C Address Selection

The MCP23017 contains three address-select pins, which can be tied to Vss or Vdd.  This gives 8 possible I2C addresses for each chip. To simplify address selection on the IO Pi Plus, we have included a set of address selection pads which can be configured by applying a small solder bridge across the required pads. The I2C address table shows your IO Pi Plus's recommended configurations and associated I2C addresses.

Disconnect the IO Pi Plus from the Raspberry Pi before changing the i2c address. The address pins are tied to GND (low) via a 10K resistor, so the jumper is used to connect a pin to Vcc (high).

Default Configuration (IC1 = 0x20, IC2 = 0x21)

I2C Address Table

2 1 0 Address

IO Pi Plus

£14.39 each (excluding VAT: £11.99)

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Important Information

This development board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by to be a finished end-product fit for general consumer use. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards. Persons handling the product(s) must have electronics training and observe good engineering practice standards. This development board/kit does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore may not meet the technical requirements of these directives or other related directives. Note: documents in Portable Document Format (PDF) require Adobe Acrobat Reader 5.0 or higher to view, download Adobe Acrobat Reader or other PDF reading software for your computer or mobile device.