Regardless of my entry into HA and the first hurdles, an idea came up between my wife and me today that I don’t know whether it can be implemented. Since the matter is rather hardware-specific, I’ll briefly ask here whether this would be conceivable or useful. If that the wrong board or any better to place, let me know please.
The following idea:
Pi3 with UPS (StromPi or similar) running HA
HomeMatic transceiver on the PI for 4 radiator thermostats
Connecting the Pi via USB to a smartphone running USB tethering
Access from outside (preferably only from a specified URL) for monitoring.
Transmission of temperatures and valve positions every 2 or 3 hours to this URL
Ultimately, this is a solution for an empty apartment so that a heating failure in winter can be detected in good time and acted accordingly.
It must not a Pi3; it can be all small/cheap board that I can power by batteries… (the UPS relies on lead-GEL batteries; reliable, safe, robust… space and weight don’t matter)
What I really don’t know is whether you can pass the network to the Pi via USB and how that works. Furthermore, I don’t know whether HA runs on a Pi3 or whether the performance is sufficient for this small task.
The RPi3A+ has 512Mb of RAM. HASOS has a realistic minimum requirement of 1Gb of RAM, and really needs 2Gb+.
Set the phone as a WLAN hot-spot and use Wi-Fi.
Homematic devices are slow to report in, so you need to have the RPi running at all times and you need a CCU, either as a standalone or as a virtual one on the RPi.
A phone running hotspot will typically deactivate it when no clients have been on for a while.
UPS will eventually die from the constant running of RPi and phone.
I would look into a simpler setup.
Use independent thermostats, so no connection is needed.
Add temperature sensors to ESP devices and the more sensors to a device the better.
Place ESP devices where they can be fed from the UPS, but still monitor the rooms.
Use a 4G router with VPN option.
Set up VPN gateway at your home and let the 4G router connect to it automatically.
Mount all the ESP devices and the 4G router on a timer and set it to wake up at certain times during a day.
The timer will wake the router, that will connect to your homes VPN gateway.
The ESP devices till wake, take temperature measurements and send it to your home.
The timer will cut power again.
hmmm, that’s indeed maybe a better way to go.
Thing is that I haven’t a wired internet there so I have to use a phone for it or a 4g/5g gateway. From an other try 2 years ago I know that creating a VPN tunnel via a phone/mobile provider often goes wrong due the mobil provider try to stop things like that; don’t ask me why… If I like VPN over 4G it goes expensive…
At the moment, all of my family use a card with 12G data volume / month for just 10€. For a wired DSL I have to pay more the 35€. That’s the base the idea comes up with an old, unused smartphone.
An other way came up a hour ago… The so called “FritzBox” are able to use a smartphone as gateway via USB. So I’m on the search for my older FritzBox (to get old and forget things is shitty… trust me). If I find them I will test if they disconnects while no data are going in/out… Maybe that’s the way? We will see…
BTW: FritzBox need 12V so it’s not a problem to drive them with a 12V battery if the mains supply going down sometimes (thunderstorm or excavator pull a cable…). If that work then I can Place a 2-wire thin cable in each room and use it to supply the ESP’s via StepDown… (sorry… loud thinking)…
Edit: Just use the cables to connect 1wire sensors and one ESP seems enough… well?! Haven’t to run at full speed…
I would have suggested the VPN in all the cases, but if you can accept the lower security, then it would work still.
And Fritzbox might work. It would then be the same as a 4G router.
VPN is certainly the better choice, but what’s not possible… If I ensure that the data can/may only be transmitted to a specified URL (DDNS), that should be secure enough
yes, that’s true with the router… But don’t cost any more due I have in stock
