Is it possible realizing my project with open HAB?


I am planning to build my own home automation system with the following sensors/actors (=CLIENTs)

a)About 5 relay-outputs
b)About 6 temperature and humidity sensors
c)About 15 PIR sensors or other sensors which can be 0 or 1 (detecting a relay contact)
d)About 3 little boards with LCD Display and a little buzzer
e)About 5 outdoor ip-cams with onvif (only if possible)
f)The central HOST unit could be a Raspberry Pi 3 (it should be the central intelligence for organizing the whole system). Or do you recommend another board as host (server) system?

The power supply and the communication of each device a)-e) should be realized over a PoE-Switch.

I have already build one Raspberry board with PIR sensor which is sending an alert with python over MQTT. But the MQTT-Client on my android smartphone is only able to connect to one MQTT-Host (Raspberry)

For me it is very important that the system is also working without internet connection. Even if there is no internet connection available, I want to get an alert on my handy in my local LAN. Additionally it would be very great, if there is a cheap sms modul for the Raspberry, so that it can also send a sms if there is no internet available.

Now I found your home automation software „OpenHAB“ today and it looks very cool!! But I asked myself what is difference to Blynk and other such software. Which would be the best for me?! Of course I am looking for a simple way to realize my little project.

So can I realize the following things with OpenHAB:

1)How should the CLIENTs communicate over LAN with my HOST? There are lot of sensors, so I need a method which doesn’t need too much performance, so that the raspberry is good enough for this job. Some signals of the clients are very short, so it has to detect it. It always has to listen.

2)Is there a max. number of sensors and actors for using your OpenHAB? Is it possible that the HOST (e.g.Rapi 3) can handle all the sensors/actors and the web-UI.

3)I also want to integrate some specific functionality, for example: A sensor never should be active / send a notification between 8-9 o’clock or it should allow one activation without alarming me in that time. So do I have the possibility to adapt the functionality of OpenHAB according my own requirements?

4)What programming language do I need for OpenHAB? Is it easy to learn?

Here I have additionally a few hardware questions:

1)As HOST I thought of an Raspberry Pi3??? What would be the best board as CLIENT with ethernet, mirco-usb and the GPIOs for my sensors??? It should be cheap (because I need much) and also easy to use.

2)Many of my sensors are working with 9-16V, so 12V would be great also because of working with emergency power (battery). The Raspberry board or other development boards are often working with 5V. So I always need the both voltages 5V and 12V on my CLIENT boards. How can I realize that?

Sorry for so many questions, but of course I am searching for the best and easiest way :wink:

A very clean solution is to use only one MQTT broker in your network, all other services should publish or subscribe to this broker. You can easily run this broker on the same raspberry as your OpenHAB instance.

If you do not have a router that requires internet connectivity and will not use services that require internet connectivity, it can be accomplished. I have not used email notification, but i would believe that in order to send and receive emails you will need an email server. OH (openhab) supports other push services, maybe one of them works (I do not use it myself)

Welcome, and reading all your use case, not sure whether I would call it so simple and little. OH probably gives you the best integration of services, but there are others. Some aspect come down to preferences, if flexibility is important OH may be the best choice.

Probably the easiest solution is have all your sensors, etc publish to MQTT, OH then can subscribe to what you need.

I am sure there is and at some point there may be a performance problem with raspberries, but there are people on this forum that use hundred’s of sensors and devices with a raspberry and have seemingly no performance issues

You will need to read up the documentation and tutorials ( to get a full picture. Rule based automation is an absolute strong suit of OH2. Your use case can easily be implemented in rules. The language is XTend, OH2 in generally is Java based, so some knowledge of Java and its derivatives will certainly be extremely helpful.

As said above and RPI3 can easily be the server.
For sensors you may want to look iot ESP8266 solutions. Some of the popular DIY solutions are, ESP Homie or ESP Easy. The advantage is the great versatility and the very low price. Best is to use them with MQTT, the solutions above all do that.

Level shifters will be your friend, e.g., (this is no endorsement as it was simply the first that popped up when I googled it)

Hope that helps