openHAB - 2

Andreas 'ads' Scherbaum

The openHAB display in the kitchen is still the problem child. Occasionally it just stops, other times it does not refresh the HABpanel, even though it has a connection to the openHAB server. Then there is the problem with the network card in the Pi. And - ok, that's a server-side problem - occasionally the weather stops updating. All in all that's a lot of trouble for a display which is just supposed to run standalone.

In the latest iteration I looked into activating the integrated hardware watchdog in the Raspberry Pi. Checking the temperature it never goes above ~55°C celcius, even though the display is in an almost closed frame and can't exchange much heat with the environment. But nevertheless occasionally the Pi just halts, and stops operating.

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As mentioned in my previous openHAB blog post: it seems to be too much to ask to have a reliable and working display in the kitchen.

Another problem I found is that the weather data occasionally does not update. Everything seems to work, no errors in the log, just no updated data. Of course this results in outdated weather info in the kitchen, and the threat that "someone" will buy a regular weather station and render my 7" Raspberry display useless.

After fighting with logs and debugging and not finding any real clue, I decided to tackle this problem from another angle, and regularly check if the weather data is up to date.

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Don't you love it when things suddenly stop working?

In my openHAB installation I have a check which verifies that the weather data is up to date. Otherwise it restarts the openhab2 service. And this check stopped working ... Leaving the kitchen display not updated for a longer time. The same display where I expect the entire installation to "just work", and don't create so many different problems. Seems to be a hard problem to have an openHAB installation without any trouble ...

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openHAB is a stream of pure joy when it comes to debugging. Especially when all I want is a small display in the kitchen, working autonomous and without the need to restart it all the time or login to fix issues.

The latest installment of that endeavor was a black screen in the browser, with no way to even get to the usual HABpanel controls. After some debugging, it turns out that the file "habpanel.config" (/var/lib/openhab2/config/org/openhab/habpanel.config) on the openHAB server was destroyed, or more accurate: shortened to 4829 bytes. Lucky me I have this file in my Ansible playbooks, and whenever there is a change, a copy of this file is fetched to my Ansible host. From there it goes into my backups, and I can restore a couple dozen versions back, if needed. So not all is bad, but still something is not working as expected. First I installed a copy of this file from my backups - but turns out shortly later the file is shortened again. Later I figured that the file is always shortened when the openHAB service restarts. This particular instance was still running openHAB 2.4, and I used this opportunity to upgrade to 2.5, test my Playbooks (and exclude the one config file from everything) and see if the problem persists. It does. Except that after upgrading to 2.5 the file is no longer shortened to 4829 bytes, but to 4875 bytes.

Every time that happens, the file ends somewhere in the middle of the HABpanel panel configuration - and naturally the HABpanel service can no longer read that file and shows a blank screen. I would wish that it rather shows an error message, or does something useful here, but oh well.

For a while (and mostly because I was busy with other tasks) I helped myself by changing the owner of "habpanel.config" and the directory this files lives in to "root:root". This threw a couple other errors into the logfile, but helped somewhat because the config file got no longer destroyed when the service restarted.

Andreas 'ads' Scherbaum

Previously I blogged about how the washing machine and the dryer are integrated into the openHAB home automation system.

For a while I had a standard "Dummy" widget in HABpanel, but that didn't look very nice, was very standard, and the different icons for different states don't really work. When I started integrating another Raspberry Pi with a touch screen (blog post to come), I refreshed the HABpanel, added another dashboard, and along the way I wrote a new "Template" widget for the washing machine and the dryer.

This project had a number of small goals:

1. Make the headline (the name) bigger - in the dummy it seems to be hardcoded, and very small
2. Use the proper icon for every Item state (running, finished, standby)
3. Change the background color of the widget according to the state of the Item

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After setting up OpenWeatherMap in openHAB, I had another project on my list: send a forecast for the next day.

That is rather easy to do with a Cron rule.

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Next item on my home automation todo list: weather, and forecast. No good system without that data!

After exploring the options which openHAB supports, I settled for OpenWeatherMap. Note: you need an account with OWM, the basic functionality is free, the paid options give you more and better forecast.

And of course, I install everything using Ansible, and can just repeat the entire installation if something does not work.

This setup is also used in a weather forecast for tomorrow.

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You might know that problem: the brand new SSD in your system is super fast, but after a good time using it, the card is dead. Unlike spinning disks, which usually fail over time, and show I/O errors by blocks, SSD cards are prone to a problem called "Wear leveling". Blocks which are written more often will "wear out", and become unresponsible. More writes increase this risk. And a typical openHAB system does a number of writes all the time: every time an external status changes, it's written to the event log. By default the syslog is written to disk as well, and then there is a myriad of systemd services, writing status information into files.

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A while ago I posted about adding a Fritz!Box to openHAB, using Ansible. Now I had to use the Playbook to install another Raspberry, and found that some parts are missing in my posting. Mostly at the end, when it comes to configuring the Fritz!Box.

Therefore let's run over all the steps again, and make sure that everything is covered.

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While diving deeper into my openHAB installation, the need for notifications on mobile phones came up. After some research, I settled with Pushover, which provides Android and iOS apps, as well as Desktop notifications. openHAB Rules have support for Pushover, and everything works well together.

Except when Android decides to kill apps, because they sit idle and do nothing. It so happens on my Huawei phone that notifications are delivered to the device, but no popup shows up. Only when I open the up, suddenly all the messages are there. The Pushover FAQ has an entry for this, even for Huawei phones, but it is outdated.