40-way Ethernet Digital I/O extension for Loxone

Low cost 40 way digital I/O board, used to extend available IO to the loxone miniserver. Based on teensy 2.0 ++

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This project shows how to build a low cost reliable 40-way digital input or output board- designed to integrate with the loxone mini-server. This was needed as our project needed over 200 digital I/O's and to do this using loxone extensions would use too much space and money!

I've nearly completed building my own home, and have used the loxone mini-server to supply the home automation.  When specifying the server, we quickly realised we would have to find another solution for all the digital io.   
We have 43 light switches - but each light switch has 4 contacts - making 172 inputs just for the light switches.  Add to that 20 door & window sensors, plus blind controls, PIR sensors, under floor heating actuators and pumps.  You get the idea.
I chose the teensy 2.0++ as it had a large number of digital IO on the board.  We did consider using I2C io extension boards, but physical size is a factor and it was easier for us to make it compact using the teensy.
I'm not a hardware expert at all!  But the system we have made is bullet proof reliable.  The software and interface to the loxone does not use any polling at all- so all the double/triple clicks work flawlessly with the loxone system.
The boards have a web interface which is really important for setting up and diagnostics as you have feedback showing which inputs or outputs are active.

In our build we have 2 sub-boards each with 4 nodes - making a total of 8 nodes with a capacity for 320 i/o.  Each sub board has it's own 5v 5 port switch, and a POE splitter - the whole board being run by 1 port on my POE switch.

It was a challenge to get 40 I/O available on the teensy 2.0.  We needed 4 pins for the ethernet connection & 1 pin for the on-board LED.  Using the teensy's interior pins, and re-purposing one of the UART pins we were able to have 40 pins usable for io.  The UART pin needed an external pull-up resistor to make it usable for normal io.

Arduino teensy++ 2.0 source code

x-zip-compressed - 18.17 kB - 05/30/2020 at 10:04



Sketchup model for the frame mount

SSEYO Koan Play File - 109.65 kB - 10/21/2017 at 10:14



STL model for the frame mount

Standard Tesselated Geometry - 56.72 kB - 10/21/2017 at 10:14


View project log

  • 1
    Prepare vero board

    A standard size vero board can be cut in half to make 2 digital IO nodes.

    And I used a drill bit to cut the tracks.  These are for the 9 pins that need to be re-routed as they are not used directly as IO pins (apart from the 1 UART pin that needs the pull up resistor added).

  • 2
    Prepare the teensy & vero board
  • 3
    Mount the teensy on the board

    And add the pull-up resistors

View all 5 instructions

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christofplay wrote 11/15/2021 at 22:22 point

Hi. What wersion of Arduino IDE did you used? I have compilation error for Teensy ++2 board.

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tejush44 wrote 04/13/2021 at 09:51 point

Hi, this is teju from wiznet india, This project is very impressive, if u dont mind we have created our wiznet maker site so wanted to post ur project in that site.

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andrew.crockford wrote 11/15/2021 at 18:34 point

Sorry for the long delay for my reply. But, yes absolutely please add this project to your site. Let me know if there's anything else you need. Ta 

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