I am new to openHAB and are looking ad a bit of advice in the direction I should take. I have openHAB install on Ubuntu on my HP Mini Server. My first target is to monitor the temperature around the house but as cheap as possible.
I was thinking of going down the Arduino route; is that the best route ?
Can I use one Arduino for all upstairs and one down stairs, then run multiply temp sensors from each one ?
Can I then use a ethernet shield to communicate back to the openHAB server; is that best way ?
I would agree with @Gad_Ofir. Trying to do automation on the cheap is a disaster waiting to happen. It’s a false economy.
There are loads and loads of tried, tested and robust products to choose from. The great thing about openHAB is that it’s the middleware component and will interface with a good number of automation protocols. So your not bound by one manufacture or protocol.
I have a number of sensors around my house, I’m using the ST814 from Everspring. Not only do I get the ambient temperature, I also get the humidity level. These are Z-Wave devices and very configurable. They also have a display so that’s an added bonus, plus they look stylish to a degree.
Check out the DIY section for some ideas, and I’ll pitch my sensor design as an option (it also has temperature/humidity plus an OLED sreen for local display). I’m working on some improvements now to make it modular and accept more sensors (luminosity, motion, environmental, etc…)
I like distributed sensors, running on ESP8266 boards (cheap, WIFI enabled with a good # of GPIO pins for multiple sensors). Using ready-made firmware like ESP Easy or Tasmota also makes these devices super simple to set up. The protocol of choice for getting the data into openHAB is MQTT.
Arduinos are cool for prototyping and such, but to get a finished, wifi-enabled product, you need to put in more $ (an Arduino Uno + Ethernet Shield will cost a lot more than an ESP8266-based NodeMCU board).
Having set up sensors both with Arduino and with ESP8266 I’ll recommend the ESP8266 approach, unless you really really want wired. They are cheap, especially if fast shipping isn’t a concern, and WiFi is built in. They also have a number of firmwares (Tasmota, ESP Easy) so you don’t even need to code them, just wire them up and configure them. In terms of cost and time, they are probably the best choice.
As with Arduino, there are several models to choose from. I’ll recommend the NodeMCU because:
the programmer is built in meaning you only need a micro USB to upload the firmware or your custom code
fully compatible with the Arduino IDE for custom code
lots of GPIO pins, including one analog pin
last time I ordered some I got them for less than $5 a piece
there are lots of stuff you can get or make around them like Bartus’s package
It depends on what you are trying to economize. There are plenty of reasons why DIY and cheap may be the better answer:
to learn and get started with DIY electronics and microcontrollers
the user has time but not money
wants to prototype something before spending more money
is solving a problem that doesn’t warrant spending the cost for a commercial device
commercial devices do not exist or are not affordable for the needed use case
Without knowing more about the OP’s situation and goals I don’t think it is fair to make such a blanket statement.
I do agree that if you are trying to get a solution up as fast as possible using as little amount of time as possible then choosing a commercial option would be the better choice. But that is not everyone’s goal.
Personally, I never would have gotten into home automation in the first place were it not for the need to build a DIY garage door controller. Had I purchased something off the shelf that would probably be the only thing I’d have automated to this day. But it was the DIY effort that lead me down the path to first Home Gini and then to openHAB.