Single board computer projects

Single board home server with Debian, openHAB 2 and MQTT

last updated: 29/01/18

My beaglebone was for some years a faithful server for my home data (photo-voltaic, heat-pump ...).

With more and more python scripts it had his problems and I got some times out of memory errors from the kernel. As I couldn't find the real cause of the errors (gnuplot very slow with big data files and many instances of gnuplot running at the same time?), I decided get another server for generating graphics.

In the meantime I got an Udoo X86 from a kickstarter campaign, and I will try to configure it as home server using MQTT and openHAB 2.

The Udoo advanced is a fan-less bard with an Intel Curie (x86 no arm) processor and 4GB RAM and a SATA port. Its much faster than the beaglebone or raspi.

Make a bootable USB-Stick from an .iso-file

The operating system will be debian stretch (this will also work for other distributions). Download the .iso file for net install (in my case: debian-9.3.0-amd64-netinst.iso).

To burn an .iso-file to a USB drive, you can use UNetbootin. UNetbootin allows to create bootable Live USB drives for Debian, Ubuntu, and other Linux distributions without burning a CD. It runs on Windows, Linux, and Mac OS X. You can either let UNetbootin download one of the many distributions or supply your own Linux .iso-file. The user interface is easy to use. Install in Linux with:

    sudo apt install unetbootin

In Linux you can also use the dd-command on the command line. Insert the USB drive (do not mount the drive), open a terminal and type dmesg. Now you see the name of your your drive (e.g. sdb, sde, ... ).

Now type the following command to burn the .iso-file: bash sudo dd status=progress if=debian-9.3.0-amd64-netinst.iso of=/dev/sde bs=4M

To test the burning, we can use QEMU, a machine emulator and virtualizer to boot into the usb drive. Install qemu (apt-get install qemu) and run the following command:

    sudo qemu-system-x86_64 -hda /dev/sde


Connect the external SSD

The power header of my SSD adapter has just two pins (5V and GND) in 2.54mm raster. Udoos header is 2mm raster with 4 pins (NC, 2 GND and 5V). A little hack was quickly done:

Udoo<em>SSD</em>circuit Udoo_SSD

Connect a mouse, keyboard and HDMI display to Udoo to proceed. Udoo needs a 12V, 1A power supply (5-6W).

Install the operating system

Without a Stick Udoo boots in a boot shell. The Bios is configured to boot from USB, so power it up with the USB Stick inserted. If you need to change things in Bios, press ESC at boot.

After booting from the USB-Stick, choose the graphical install. Choose the right language, localization, configure your keyboard and enter a hostname (e.g udoo-server) and a domain name. If you leave the root password empty, debian will disable root and the normal user account will be given the power to be root with sudo.

After this create your user account.

I do the partitioning manually (Partition disks: Manual), and want to use the efi mode. All files are stored on the external SSD.

nr size device mount point file system partition
1 200 MB /dev/sda1 /boot/efi esp efi system partition
2 16 GB /dev/sda2 - swap swap partition
3 128 GB /dev/sda3 / ext4 root partition
4 106 GB /dev/sda4 /home ext4 home partition

After choosing a download server the installer asks for choose the software to install. As a server, I don't need a GUI, so I install debian headless only with an SSH server.

Update and upgrade

After reboot we log in and get the latest versions of all programs:

    sudo apt update
    sudo apt upgrade
    sudo apt dist-upgrade

It is a good idea to install the terminal file manager "midnight commander" (mc) to search and edit files as root in terminal (sudo mc), and htop an interactive process viewer.

    sudo apt install mc  htop

Set timezone

    sudo timedatectl set-timezone Europe/Luxembourg

Control with date. (to list all timezones : sudo timedatectl list-timezones)

Add sudo

If you have a root account and want to use sudo for your default user:

    apt install sudo
    addgroup username sudo

Static IP address

The IP address of your server is given with DHCP. To get it use the following command:

    ip a

To get a static IP adress is easy in Stretch. Use the editor nano or mc (F4) to append the following to the file /etc/network/interfaces.

# The primary network interface
allow-hotplug enp2s0
iface enp2s0 inet static

Save with CTRL+O and exit with CTRL+X and reboot.

Create a backup

After all this work we want to create a backup of the installation. To do so we use a Live USB Stick (e.g. Ubuntu) and boot the server from the Stick (ESC at reboot, Boot Manager).

We connect an external USB-HDD with more space then our SSD, open it in a filemanager (mounting) and locate the mount point (e.g. /media/ubuntu/label). After this we use dd to get an image. A pipe through gzip reduces the size.

    dd bs=1M if=/dev/sda | gzip > /media/ubuntu/bu/udooServerDeb.img.gz

Log in with SSH

Now we can remove the display, keyboard and mouse an login from another computer with SSH:

    sudo ssh username@

or as root:

    sudo ssh root@

If we don't know the IP address of the server after a reboot, because it was given by DHCP we can use the nmap-command. If nmap is not installed (for Windows look at ):

    sudo apt install nmap
    sudo nmap -sP 192.168.1.*

Look for the IP address of your server (e.g. and log in with SSH (putty on windows):

    sudo ssh username@

Install openHAB 2

More infos in

OpenHAB 2 is written in Java, so we need a JAVA platform (For ARM sb-computers install the 32 bit version!).

As sugested we use Zulu:

    sudo apt install dirmngr
    sudo apt install software-properties-common python-software-properties
    sudo apt-key adv --keyserver hkp:// --recv-keys 0x219BD9C9
    sudo apt-add-repository 'deb stable main'
    sudo apt update
    sudo apt install zulu-8

Now we will install openHAB 2 stable release:

    wget -qO - '' | sudo apt-key add -
    sudo apt-get install apt-transport-https
    echo 'deb stable main' | sudo tee /etc/apt/sources.list.d/openhab2.list
    sudo apt update
    sudo apt install openhab2

Now we can start openHAB 2 by and test if its running:

    sudo systemctl start openhab2.service
    sudo systemctl status openhab2.service

To start on installation, execute the following commands to configure openHAB 2 to start automatically using systemd:

    sudo systemctl daemon-reload
    sudo systemctl enable openhab2.service

Install mosquitto

Install the mqtt server with:

    sudo apt install mosquitto

Set up the MQTT Binding for openHAB 2

In /etc/default/openhab2 we find the config file. In this file we find the links to the openHAB 2 default paths:


First we open openHAB 2 in a browser with the url: serverip:8080 (e.g Then we select Paper UI tio install the MQTT Binding. Search in Add-ons Bindings for MQTT Binding (Binding-mqtt1) and install it through Paper UI.

Because it is a openHAB 1.x Binding, we need to configure the Binding settings through a configuration file. You find the configuration file mqtt.cfg among the service files (etc/openhab2/services/mqtt.cfg). Replace the #<broker>.url... and the #<broker>.clientId... lines with:


It is important to restart openHAB 2, to take the changes in account:

    sudo systemctl restart openhab2.service

If all went well you will see the following in /var/log/openhab2/openhab.log:

MQTT Service initialization completed.
Starting MQTT broker connection 'mosquitto'

Configuring openHAB 2 for the smartyreader /usr/share/nano/openhab.nanorc

OpenHAB 2 defines the following base components:

Bindings: the numerous add-ons to communicate with your devices
Things: your physical devices represented in openHAB 2
Items: properties and capabilities linked to Channels of your Things
Groups: collections or categories containing Items
Sitemaps: user-defined front-end interfaces to arrange Groups, Items, ...
Transformations: helper functions to transform your data
Persistence: services to store data over time
Rules automation logic, the “smart” in your Smart Home!

Defining the Thing (our smartyreader :))

WE need a configuration text file for the smartyreader (our Thing) in /etc/openhab2/things/.

The syntax for Things is defined as follows (parts in <..> are required):

Thing <binding_id>:<type_id>:<thing_id> "Label" @ "Location" [ <parameters> ]

So we type: Thing mqtt:device:smartyreader "smarty1" @ "basement" [ip=""]

and save this in a file named smarty1.things (directory /etc/openhab2/things/).

The syntax for Items is defined as follows:

itemtype itemname "labeltext [stateformat]" <iconname> (group1, group2, ...)
["tag1", "tag2", ...] {bindingconfig}

Fields must be entered in the order shown, itemtype and itemname are manadatory and all other fields are optional. Fields may be separated by one or more spaces, or tabs and an Item definition may span multiple lines.

Bindingconfig for MQTT Items:

 <direction>[<broker>:<topic>:<type>:<transformation>:<regex_filter>], ..."}
    String Smarty1__Consumption "Smarty1 Consumption [%s]" <smarty> (gSmartys )  { mqtt = "<[mosquitto:basement/smarty1:state:default]" }

If all went well

sitemap smarty label="Smarty" { Frame label="Smarty" { Text item=Smarty1_Consumption icon="switch" } }

Extracting JSON data

Install JSONPath Transformation addon with Paper UI (Add-ons Transsformations)

    String Smarty1__Consumption "Smarty1 Cons. [%s]" <smarty> (gSmartys )  { mqtt = "<[mosquitto:basement/smarty1:state:JSONPATH($c1):]" }

you don't need to add the "label" field to your sitemap if you already define a text label in the Items file

to be continued :)

Install paho-mqtt for python programs

    sudo apt install python3-pip
    sudo pip3 install paho-mqtt
    sudo apt install gnuplot

Install ssmtp for mailing

For mailing you have to install ssmtp (needed), mpack (for attachments) and berhaps mailutils (not mandatory):

    sudo apt install ssmtp mailutils mpack

With your editor you have to set up the defaults for SSMTP in /etc/ssmtp/ssmtp.conf. Edit the fields:


Test your mail with:

    echo "Hello world email body" | mail -s "Test Subject" my@mail.adr