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MCP23017 Break out board IOBOB

MCP23017 Break out board IOBOB

MCP23017 BoB with DIN rail mounting and proper wire to board connectors and indicator LEDs.

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Components and supplies

Apps and online services

About this project

Features

  • Reliable spring cage wire to board connectors
  • Pluggable power and I2C connector
  • Indicator LEDs to display IO state for input or output
  • Selectable address to enable connecting 8 devices to same bus
  • Functions the same as MCP23017
  • Possibility for pull up resistors (recommended to pull up at host)
  • Operation even down to 1.8 V (LED operation down to 2.5 V)

Connections

With many options for MCP23017 break out board available, there are few with proper wire to board connectors.

Spring cage connectors (Phoenix Contact 1990025) keep 20 - 26 AWG or 0.14 - 0.5 mm² wires securely in place.

Power and I2C connector can be un-plugged for troubleshooting purposes.

Mounting

Mounts to standard 35 mm DIN rail and 30 mm C-rail.

Code

Example code for ArduinoArduino
Example code using Adafruit MCP23017 library. Adafruit provides a variety of I2C capable controllers.
//Software License Agreement (BSD License)
//
//Copyright (c) 2012, Adafruit Industries
//All rights reserved.
//
//Redistribution and use in source and binary forms, with or without
//modification, are permitted provided that the following conditions are met:
//1. Redistributions of source code must retain the above copyright
//notice, this list of conditions and the following disclaimer.
//2. Redistributions in binary form must reproduce the above copyright
//notice, this list of conditions and the following disclaimer in the
//documentation and/or other materials provided with the distribution.
//3. Neither the name of the copyright holders nor the
//names of its contributors may be used to endorse or promote products
//derived from this software without specific prior written permission.
//
//THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
//EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
//WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
//DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
//DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
//(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
//LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
//ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
//(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
//SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <Wire.h>
#include "Adafruit_MCP23017.h"

// Basic pin reading and pullup test for the MCP23017 I/O expander
// public domain!

// Connect pin #12 of the expander to Analog 5 (i2c clock)
// Connect pin #13 of the expander to Analog 4 (i2c data)
// Connect pins #15, 16 and 17 of the expander to ground (address selection)
// Connect pin #9 of the expander to 5V (power)
// Connect pin #10 of the expander to ground (common ground)
// Connect pin #18 through a ~10kohm resistor to 5V (reset pin, active low)

// Input #0 is on pin 21 so connect a button or switch from there to ground

Adafruit_MCP23017 mcp;
  
void setup() {  
  mcp.begin();      // use default address 0

  mcp.pinMode(0, INPUT);
  mcp.pullUp(0, HIGH);  // turn on a 100K pullup internally

  pinMode(13, OUTPUT);  // use the p13 LED as debugging
}



void loop() {
  // The LED will 'echo' the button
  digitalWrite(13, mcp.digitalRead(0));
}

Custom parts and enclosures

Enclosure drawing

Schematics

Schematic of indicator LEDs
High treshold 3/4 of supply voltage

Comments

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