Contest Winner

@Andreas-Menzel I personally tend to replace the batteries early enough. I also have at the controller level a couple of safety checks with are ensuring 1) the "close" message is acknowledged by the sensor and if not resend it again 2) a humidity sensor in the ground checking if it is still irrigating after e.g. 2-3 hours the valve is supposed to be closed.
I've noticed if the battery is almost over and unable to close the valve once, it will likely succeed when retrying. Then of course batteries have to be changed.
Over the years I've refined this old project over and over mainly making the capacitor bigger since the valve would otherwise drain so much current to dramatically shorten the battery's life. But this is still border line for the capability of a battery powered sensor I believe.

@skywatch not really, depending on the algorithm

@Puneit-Thukral yes but for full/specified function, atsha, atmega and any sensor circuitry also need to be operational at that level.

@Puneit-Thukral but will the peripherals still work at that level? No use to lower the BOD if radio/security/sensors stop working at a higher voltage.

Beautiful work

@skywatch my 50 cents is that you might want to achieve to much. Having 2 different networks is not a problem. But one device in 2 networks, not sure if it will solve your problem.

@skywatch that depend on the key size you choose, and how you deploy the implementation (like block chaining and random initialization).
Symmetric ciphers are even quite secure in the quantum world given large enough key sizes.

@skywatch It would by much easier to share sensors on different controllers between controllers.

Controller A is the master, controller B receives updates. Domoticz supports this. Don't know about the others

@skywatch are you implying they recommend AES without an IV or block chaining enhancement? I don't think so

How ever powering from usb is not very stable. When sending multiple messages with delays my sketch sometimes stalls. Need to test with the suggested 6v power supply though. But most nodes don't need to send multiple messages quickly