Actual hardware= the need for physical connections to the openhab server

Let me start from my current situation to let you understand my question:

  • I’m automating most of my home with z-wave, transitioning from using exclusively to the z-way binding binding to OH2.2. i’m not ruling out the z-wave binding in the future… baby steps, i had most of my work already sorted on z-way, didn’t feel like throwing it away.
  • in the process of trying to connect a broadlink rf universal controller through a beta binding
  • in the process of adding tado heating functionality through it’s binding
  • future plans of electric consumption and load control, most likely through some modbus din rail mounted electric meter
  • i wouldn’t rule out some zigbee addition or some MQTT to some Shelly relay(possibly using the raspi as wifiAP to create an automation dedicated wifi subnetwork and maybe even hide its ssid
  • integrated google home control

SO: Hardware for and to the openhab server- where i’m at


  • a RasPi 3
  • with the razberry sheild connected to it
  • with it’s microUSB PSU
  • with a Lan cable conected to it

then i thought about microsd wear - so, le’ts get a sandisk ssd 30GB, and a sata adaptor
there is a cool X820 board addition for the raspberry, and you can add to it a metal casing with a fan (you can google it)

And in the near future a basic UPS is a must.

BUT -in terms of costs:
raspi + casing + ssd + ssd board will run you around 100- to 130 € depending on how good a deal you get, and the only reason i am using the gpio is for the raZberry board (i liked the idea of an enclosed unit with no stuff dongling around) - and the uZb stick is available on the market.

in my tinkering dreams i’ve started to think about purchasing an android TV box, with s912 soc, 32GB of internal storage and 3 GB of DDR4 (that woudl run circles aroudnt he raspi’s performance, and i doubt i’d get much memory wear issues, no ram shortage)- approx cost 70€- install on it armbian, and get OH running on it from there. - much less bulky of a solution, tho i’m not a linux expert, so it will be a learning process, potentially a bricking one as well.

or maybe i could get a mini pc with similar performance and start from there too.

NOW: basic connections to it stay the same(lan, psu, hdmi), but i might end up having less USB ports and no GPIO connector comparted to the raspi


  • exception made for bus cabled protocols (KNX, modbus etc), which anyhow offer some kind of LAN or Wifi interface aside from the USB ones, what fuctionalities/potential extentions/addons/integrations to OH does one loose having less USB ports and no GPIO ?

I’m not talking from a “weekend project perspective”, i’m not going to be controlling christamss tree lights from the gpio(no time, would be fun tho), i’m talking from the perspective of creating a stable server that one can park somwhere near the router, get the both and a google home powered by an UPS and rely on in daily life.

Foundation members and OH enthusiasts on the forum: what do yo use physical connections for? use cases please


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I’ll go with that.
The USBs are not an issue. You can always add a USB hub
You are loosing the GPIOs but you are only using them for the HAT. You’ll have to get a USB dongle for zwave.

I use one one these:
The thin one.

I was lucky enough to score one for free.

I’d stay with the Pi.
Moving to different HW will result in quite a lot of cost and efforts, PLUS you would be sort of getting off-mainstream (important to have as many people to have the same setup as you do when it comes to solving server/OS related problems).
Given you already run a RaZberry board that cannot be reused on any box with USB, new server HW would require changing your ZWave network over to another controller, quite likely you would need to rebuild all of your ZWave network.

Raspis CAN be tweaked to withstand that. See this post.


While i thank you VERY much for your feedbacks @vzorglub and @mstormi (i’ve learnt quite a bit already! :grimacing:)

-aside from system tweaking - is anybody CONNECTING anything PHYSICALLY directly to the gpio or usb or 3.5 jack …etc?
Put even more bluntly:
**What cables have you got attached to your openhab machine? **
Anything that is REALLY paying off that isn’t a monitor, keyboard+mouse, lan cable- amongst these cables/devices

What i wished to get a bit deeper into is - what are the tradeoffs (costs/solutions etc) in dropping the gpio, or having less USB ports and gaining more computing power (drawing more electric power at the same time- an i7 machine would need to be motivated by some mission critical idea),

I’ve seen a video of Kai connecting a stereoscopic camera via usb to gesture control - that’s something i hadn’t thought of, and he clearly states in the video that on a raspi wouldn’t work due to lack of computing power.

i’m curious - what other use cases i haven’t thought of,
that have physical requirements for the machine running openhab.

Has anybody connected physically to some obscure port of their dishwasher or washing machine? Maybe repurposing an old printer port, or serial port, or running off some pins of the GPIO - with a practical daily use? requirements?

(i know there are fancy appliances with a cloud, that’s not the desired topic either, but do share if there is something creative there)

The loss of GPIO is really only a minor concern. There is nothing that requires the GPIO pins to be on the same machine as OH. In fact, it is far more flexible when you don’t as you can then deploy little cheap EPSs or RPi 0s where they are needed and use those GPIOs, exposing the sensor data or command interface through MQTT or some other standard interface.

I agree with Markus’s advice. You already have the RPi and for less work and less cost you can get to where you want to go. You don’t have to go with a 100-130 € external SSD.

But if you want to move to a new machine, that is fine too.

Yes, but not on the same machine that is hosting OH. I have my OH server mounted under my office desk. But I use GPIO to control my garage doors, sense the open/closed states of my doors, and sense the light, temp, and humidity in several rooms. It is impractical to run wires to do all of this so I have RPi 0ws and NodeMCUs that send the sensor data or activate commands to the OH server.

None. It is completely headless with only the Zwave/Zigbee combo USB dongle attached.

But I don’t have a need to. YMMV. It all depends on what technologies you use and what technologies you intend to use. But don’t forget, most of the time you are not required to physically attach many of these devices directly to OH. Heck, with socat/ser2net you don’t even need to plug the Zwave controller to the OH host (can be useful if your OH server location isn’t the best place for your Zwave mesh.

No, but if I were to I would use a special purpose RPi 0W or NodeMCU to wire into that interface and receive data and command the device over MQTT. I don’t want to have to locate my OH server to the kitchen cabinet and I don’t want to have to run wires from my office to the kitchen to achieve something like that.

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The UPS USB cable goes in there to gracefully shutdown in case of porwe failure.
Also because the server is located near the telephone cable entry point I connected a modem to be able to detect incomming phone calls and pause the TV!! I wanted to display the caller on the TV but called ID in the UK is impossible without expensive modems. So that’s delayed…

But as @rlkoshak said, if the sever was located somewhere else, I would have used a Raspi for that purpose.

I was not able to get the sound running on this machine with Ubuntu Server 18.04 so I gave up pluging in little speakers and instead I have a Pi 1 running node-red receiving input to play sound. I had to work around the say action` but it works just the same.

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@rlkoshak - you’ve made me discover a world of possibilities O.O

I am quite new to diy electronics, so far have mostly used ready made stuff and rather tinkered with tuning the automation on top of it, but that might change.

1- after researching node mcu and rpi 0w, also the z-uno device makes complete sense to me now, to import in z-wave any project done on arduino, i can see the logic there. I wonder how does it stack up against the flexibility and power mqtt offers in aquiring signals paired with something like node red. this might become worthwile studying for myself. Really interesting field.

2- IF the broadlink binding doesn’t work out for me (or even if it does), somwhere down the line I might just follow some guide(they are available on the web) in order to connect through the gpio of the rpi an rf 433 transmitter and bind it via exec binding. I love the idea! The position is just right in my home (the broadlink sits next to the rpi to command what it needs to) and one less “box with microusb power” around. Just need o check for gpio pins availability due to the raZberry hat being connected…

When will i have the time for all of this :face_with_raised_eyebrow::rofl:

I’m not sure I understand this statement. It seems to be mixing two orthogonal concepts. MQTT is a messaging protocol that runs in top of TCP/IP or UDP/IP. There are no MQTT signals, only messages.

The majority of NodeMCU and RPi creators of diy home automation devices use MQTT to communicate with the device. A bare Arduino will usually either be wired to a computer through a serial connection and that computer translates the messages, usually to MQTT, or it communicates wirelessly using a non-wifi protocol like rfm69hw to a computer that transfers the messages, usually to MQTT, or if the Arduino can communicate on the network directly, it sends/receives MQTT itself. A NodeMCU is basically a tour of Arduino that can talk wifi.

And through that wifi mqtt messages are sent an received.
I got that.
What i meant, at my current level of understanding, was:

Mqtt provides the maker with what I see as about total freedom to self define a string’s meaning.
So in the scenario of hooking up a node mcu to a washing machine service port, the biggest issue would be prior knowledge of how to make sense of the signals coming from that port, whether the vendor shared that publicly. If that is known, one could recognise “cycles” and when a happens recognise it as “prewash”, when b happens recognise it as “rinsing”… Or, if shared by the service port, transmit via mqtt messages over WiFi the data regarding current rpm etc

This is what I meant by flexibility.

I am not sure(as of yet, will research as it intrigues me because I have mostly z-wave devices) how flexible that kind of work is with a z-uno on z-wave, whether there are restraints on data point types and acquiring signals, or whether it has just at the same level of flexibility.

My pi is in my “media closet” along with several other things. This closet is strategically chosen to have easy attic access for wire runs. I have wired gpio connections to:

  • 120v relay controlling tv backlight (turn on backlight when content is playing)
  • reed switch from another tv which is open with tv off, closed switch with tv on - reed switch/relay plugged into usb power on tv
  • hardwire smoke detector relay - open= no fire, closed= fire
  • soon my doorbell will be added

My USB connection goes to my Insteon hub.

With that - I also have my own small army of esp8266 boards, I choose wemos style which as far as I can tell is functionally equal to nodemcu. I’ve got a few running tasmota and a few running my own arduino code.

The smoke detector is actually one of my family’s favorite automations… it’s linked in nodered to the Pizza Hut twitter bot so “burning dinner” makes a random pizza order from our saved favorites. When friends come over we let them hit the alarm test button to order dinner.

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Nice one. But in order to stay on topic: you should think of going wireless with that many devices.
You could have more smoke detectors to order pizza e.g. right from your bedroom …

Mmmmh… Pizza in bed :pizza:

The big smoke detector companies all make in-line hardwire relays to “integrate existing hardwire alarms with security systems and other equipment in the house…” as they describe it.

My house has 8 linked hardwire alarms so I picked up a first alert relay for $10, wired the normal open relay to a gpio, and now all smoke detectors in the house also communicate with openhab over gpio (they always all alarm together).

I thought it was a great use of the pi gpio! Of course a WiFi or zwave chip could do this as well - just depends how far your wires are from your openhab computer.

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