In general, reinventing the wheel seems like a waste of time. But I decided to roll my own anyway. The official software is closed source, requires an account, and only runs on Microsoft Windows. Most open source Max! projects are very incomplete, but all the feature complete solutions are part of complicated home automation systems (FHEM, openHAB, Node-RED). And because I never used the original software, I needed something that will even work if you begin with a new, unconfigured Cube.

Of course, my program is incomplete too. It does exactly what I need, but not much more.

• executable max
• Perl class Max
• Perl class Max::Device
• Perl class Max::Room

Ease of use:

• No "portal" account or any other cloud service needed.
• Works on new Max! Cubes out of the box.
• Works on most Linux systems without installing additional software.
• No configuration is needed, it can find the Cube automatically.
• All features can be used on the command line (beginner friendly).
• All features can be used via the Perl module (for advanced users).

Supported actions:

• Pairing new devices, assigning room IDs.
• Assigning names to rooms and devices.
• Cross-linking devices within a room.
• Setting (overriding) the temperature in a room.
• Switching a boiler on/off via an external program.
• Text based short or detailed status overview.

Contrib scripts included:

• max2graphite will dump room statistics to a Graphite server running on localhost.
• set-gpio can be used to drive a GPIO pin (e.g. on a Raspberry Pi) to switch a boiler via a relay.
• welterusten (Dutch for "good night!") is an example of scheduling with at, as an alternative to fixed time schedules.

All regular Linux distributions come with Perl and Perl modules pre-installed.

To run this program on a router running OpenWRT, install perl and its core modules:

    opkg update
    opkg install perl perlbase-essential perlbase-config perlbase-cwd \
        perlbase-findbin perlbase-io perlbase-list perlbase-mime \
        perlbase-socket

This repository comes without an installer and installation is not necessary because you can run it from the repository.

But you could do something like:

    git clone git://github.com/Juerd/eq3-max /opt/eq3-max
    ln -s /opt/eq3-max/bin/* /usr/local/bin

Assuming out-of-the box Cube:

1. Get a debug dump to see if anything works at all. You should see your Cube's serial number and RF address:

  max dump

If it cannot find your Max! Cube via UDP, you can set the MAX_HOST environment variable. If discovery does work, you may want to set the variable anyway, because that will make every call half a second faster.

  export MAX_HOST=192.168.1.9
  max dump

2. Pair all the devices in a room. Pick a room number; in this example "2" is the room ID. It might be useful to pick different room numbers than your neighbours :)

  max pair 2  # follow instructions to add to room 2
  max pair 2  # repeat until done

3. See if the devices show up in the overview:

  max status

4. If you added multiple devices, set up links between the devices in the room:

  max crosslink 2

5. Set the temperature of the room:

  max set 2  21.5

6. See if the devices report the new setpoint:

  max status
  # It may take a while before devices synchronise

7. Repeat 2 thru 6 for other rooms.

8. Use 'watch' to get a live refreshing overview:

  watch max

Optionally, configure names for your rooms and devices:

    max name 2 "living room"
    max name 123abc "radiator south"
    max name 123def "radiator west"
    max name 3 "master bedroom"
    max name 4 "kitchen"
    # etc...

You could store this as a script, in case you ever have to do it again.

You may skip this part if you don't have a boiler that needs to be switched.

The Max! system by itself is not suited for use with a boiler that requires a single thermostat to indicate the demand for heating. The max switch command can emulate a simple thermostat and will execute a given command:

    max switch '/opt/eq3-max/contrib/set-gpio'

This example will call the set-gpio script with a single parameter (0 or 1) to control a relay.

Additional parameters can be specified if you need other values than 0 and 1, and the command may include %s to indicate an alternative location for the variable:

    max switch '/usr/local/bin/%s-my-boiler' enable disable

This will run either enable-my-boiler or disable-my-boiler.

• max switch needs to be called frequently, for example once every 10 seconds.
• The program is stateless and will unconditionally execute the given command, even if no change has occurred.
• It will only request heat if any room with a wall thermostat is too cold AND at least one TRV has a valve that is sufficiently opened. As such, it may take a minute after setting a new temperature setpoint, before the heater will come on.

For a dry-run test, use max switch echo.

THIS SOFTWARE MAY OR MAY NOT WORK FOR YOUR USE CASE. IT WAS WRITTEN FOR MY SPECIFIC SITUATION, BUT I HOPE IT'S USEFUL FOR YOURS. JUST DON'T COMPLAIN IF IT BURNS DOWN YOUR HOUSE...

Because I don't have all the different devices in the eQ-3 Max! range, and the vendor does not provide any official documentation, this software is based on a lot of assumptions.

If you know Perl and have the Max! window switches or an "eco button", please contribute patches.

Please let me know. I'd love to receive a screenshot or copy/paste of max status on your system.

• eQ-3 Max! protocol documentation