IO Pi Plus

£12.49 each (including VAT: £14.99)

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Features

  •  32 Digital Inputs/Outputs
  • Control via the Raspberry Pi I2C port
  • Stack up to 4 IO Pi boards on a single Raspberry Pi
  • Solder jumper selectable I2C addresses
  • External 5V Input with isolation solder jumper
  • Based on the MCP23017 from Microchip Technologies Inc
  • Configurable interrupt output pins - Configurable as active-high, active-low or open-drain
  • INTA and INTB can be configured to operate independently or together
  • Configurable interrupt source  - Interrupt-on-change from configured register defaults  or pin changes
  • Polarity Inversion register to configure the polarity of the input port data

The IO Pi Plus is a 32 channel digital expansion board designed for use on the Raspberry Pi. The board is based around the MCP23017 16-bit I/O expander from Microchip Technology Inc. A pair of MCP23017 expanders are included on the board allowing you to connect up to 32 digital inputs or outputs to the Raspberry Pi.  The IO Pi Plus is powered through the host Raspberry Pi using the GPIO port and extended pins on the GPIO connector allow you to stack the IO Pi Plus along with other expansion boards.

The I2C address bits are selectable using the on-board solder jumpers. The MCP23017 supports up to 8 different I2C addresses so with two MCP23017 devices on each IO Pi you can stack up to 4 IO Pi boards on a single Raspberry Pi giving a maximum of 128 I/O ports.

The IO Pi includes a 5V port that can be isolated from the Raspberry Pi via an isolation solder jumper so you can use a separate high current power supply to power the IO Pi reducing the load on the Raspberry Pi. Use of an external supply is recommended if you plan on connecting more than one IO Pi Plus to your Raspberry Pi.  The 5V input is compatible with our 5mm screw terminals.

Legacy IO Pi Versions

See our KB article for previous versions of this board.


Specifications

Input Ratings & Specifications

Spec
Ratings
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

Schematic

Click to download
Click to download schematic PDF.

Mechanical Drawings

Mechanical Drawing

Click image to enlarge


Assembly

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

The digital 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 simply press the 40 pin connector down onto the Raspberry Pi GPIO pins with the board sat over the top of the Raspberry Pi.

If you are installing more than one IO Pi on a single Raspberry Pi board then you will need to configure the address select jumpers for each IO Pi.

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

 

PCB Header Assembly Jig

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

Use

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 show the recommended configurations for your IO Pi Plus and the associated I2C addresses.

Note:
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 tie a pin to Vcc (high).

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

I2C Address Table

2 1 0 Address
      0x20
    0x21
    0x22
  0x23
    0x24
  0x25
  0x26
0x27

Compatibility

Model Status
Raspberry Pi Model A No
Raspberry Pi Model B No
Raspberry Pi 1 Model A+ Yes
Raspberry Pi 1 Model B+ Yes
Raspberry Pi 2 Model B Yes
Raspberry Pi 3 Model B Yes
Raspberry Pi Zero Yes
Raspberry Pi Zero W Yes
Orange Pi Yes
Asus Tinker Board Yes
Odroid Yes

Code Libraries and Demos

We have Python, C, C++, Node.js and Windows 10 IOT libraries available for this expansion board.  You can download all of the libraries from github at:

https://github.com/abelectronicsuk/ or click on the logos below for your selected programming language,


Datasheets

Microchip MCP23017


Related Items

Important Information

This development board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by abelectronics.co.uk 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.