Developing an openHAB server hardware

In addition to the quite common 1-wire temperature sensors, now also devices with serial Modbus interface can be managed by OpenHAB on the Telegea Smart Hub. As an example I used a Chinese temperature and humidity sensor.

And here is a live picture of the demo test plant from the lab.

The following devices are connected to Telegea Smart Hub (top left):

  • 4-channle USB relay card (top right)
  • 1-wire bus temperature sensor (black cable on the left)
  • Modbus temperature and humidityh sensor (bottom center)
  • magnetic window contact (at the top)
  • 2 mechanical switches (bottom right)

The whole setup is mounted into a DIN rail cabinet and it is powered by a 24Vdc power supply module.

Note that all sensors are managed by on board components and no add-on modules need to be used for this setup.

Hi Ondrej, I discovered your boar right now.

We are designing something similar based on Raspberry CM3L :grimacing: with a little bit more hardware.

The preliminary is available on this link:

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Hi all,

we have created a new Github repository to support third party applications like OpenHAB on the Telegea Smart Hub.
Some initial documentation is already there. Now you can find also the OpenHAB configuration files for the demo test plant I posted here earlier.


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I was asked in another thread if openHABian would run on the Telegea Smart Hub. Since we hadn’t tried this yet I did a quick test and the installation runs through smoothly. Just flashed the latest openhabianpi-raspbian img file to the SmartHubs Compute Module and powered it up. After about 20mins I could reach the OpenHAB web GUI and the Linux console.


With the solid state memory will there be less chance of corruption?

I answered this question in here.

But to add some information: the RPi Compute Module is designed for industrial applications so expect it to be much more robust than the standard RPi. Regarding the eMMC memory, it is very difficult to find reliable information about the durability of a specific chip but it looks like eMMC uses MLC and SD cards TLC NAND flash. MLC flash supports from 3 to 5 times more P/E (program/erase) cycles than TLC flash. Be free to google more information :slight_smile:

So i think the only way to find out is running specific stress tests.

Here is a suggestion: if there is any interest and we find a trusted community member to do an unbiased review of the Telegea Smart Hub, we would be glad to supply some free samples to run OpenHAB and try it with different deployment scenarios. Let me know.

Hello. I am very interested in testing this hardware, I have openhab running on a raspberrey pi already. However, I am new to this community.

I’d be keen to give it a try and provide an unbiased comparison to my windows and raspberry pi 3 setup…

Hi @Ckeller and @TommySharp
your Smart Hubs have been shipped to you (might take a while to reach NZ). Looking forward to your test reports.

Exciting news @ondrej1024
I look forward to trying it out for sure…

I would also like to test and review your device.

Do you also sell the things shown above like the USB relay Board? Does it fit in your din rail case anderen is it Plug and Play or ist any configuration needed?

Just got notice for this thread, very promising. If still applicable I would really like to try one of those as well. Let me know if you are still interested for Some unbiased testers.
And keep up the good work.

Hi, I am using openHAB with a raspberry for more than 3 years with a lot of binding and devices and I would be interested to test and review your server hardware, if possible.
Thank for telling me whether you are interested !
Best regards
Jetblack (from France)

Wow, looks like this article on LinuxGizmos has boosted our popularity a lot. Thanks for your interest in reviewing the Smart Hub. I will see what I can do to send out some more test samples.

We only produce the Smart Hub, the other components are provided by third party.

The relay card in the picture is a Conrad 4-channel USB relay card. It is compatible with the crelay software, which detects the card automatically and allows to control the relays via command line (OH Exec binding) or HTTP API (OH HTTP binding). Other USB relay cards are also supported but the Conrad card provides DIN rail mounting.

Otherwise we also use this 8 channel relay card, which is connected to the Smart Hub via the I2C connector. Up to 8 cards can be daisy chained, providing a total of 64 relays (this should be enough even for the most demanding Smart Home scenarios). The cards relays are controlled via GPIO lines provided by the MCP23008 Linux kernel driver.


Thank you for this usefull Information, now I need an external Temperature and humidity sensor. Do you have further information which is compatible?

For temperature and humidity a good solution is a Modbus sensor connected via RS485 to the Smart Hub which permits long cables. Unfortunately these are usually quite expensive. The sensor from our demo plant is a low cost chinese sensor which is discussed in this forum thread.

But if you can wait, we will have our own Modbus temperature and humidity sensor based on the Sensirion SHT21. It will be available at a very reasonable price in about 1 month. We are currently testing these prototypes.

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Ok Thank you, let me know if it will be possible to test and review your board. I have a question : I use 10 1-wire devices with about 50 meters of wires. Does your integrated 1-wire interface withstand such a load ?
Thank you !

The 1-wire interface the Smart Hub provides is the bit banged 1-wire protocol via GPIO pin. It has in integrated pullup of 4.7KOhm on the data line and 3.3V power supply for the bus. We have tested it successfully with up to 300m cable length and 20 DS18B20 temperature sensors. Depending on the actual cable length you need to add an additional 4.7K or 2K pullup.