433 Mhz open protocol for DIY applications

I wonder whether there is any established protocol for 433 MHz communication, that could be used for self-made devices.

Am looking for something that has the following properties

  • well documented
  • easy openhab integration
  • maintained
  • sensor mesh support (ad-hoc networking, routing)
  • low power functionality (e. g. something like scheduled transmission and time synchronization to fully power down the wireless transmitter and receiver)
  • optional support for security/authenticity or even encryption
  • code available for PIC microcontrollers
  • optional plus would be if there would be some interoperability with a RS485-base wired communication as alternative to 433MHz.

Even in case you have something in mind, that does not satisfy all those “constraints” please give me some pointers (if they are beyond google).

I’d like to put some battery powered sensors (soil moisture, temperature, water level, maybe more) around the garden over longer distances and connect them to my openhab instance. As I didn’t find suitable devices on the market I think of creating something on my own, but even with some experience in capacitive sensing, microcontroller programming and electronics, I fear it will fail due to loss-of-interest-before-finishing, if I cannot build on top of at least some communication.

Does it have to be 433MHz?

How about something like https://www.mysensors.org/?

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looks interesting, thx. Do you have experience with it? But I have to admit, that I have some trouble to find the technical details… They try to make it ease for newcomers to start right a way, but it is not so easy to find facts. I even have the impression that they would support 433Mhz via an RFM69 module.

Chechout mysensors

I have a bunch of them both battery powered and mains powered
Door and window sensors. Temperature and humidity in the rooms.

It is a mesh network so you can achieve the distance you require
A sensor will cost you between £3 and £10 depending on what you attach to it.

The openhab integration is done via mqtt. Easy peasy.

I also started with mysensors some years back and I still love it and built more and more sensors for it.

I suggest you to go buy an Adruino Uno or MEGA, two legitimate NRF24L01+ and just get started. It will cost you only about 10 $.

You can get a simple overview here: https://www.mysensors.org/about/components

Also when buying stuff for use with mysensors I can really really recommend to use the buying links on the mysensors.org store page itself, because they only link to quality, non-fake devices.

The NRF24L01+ uses the 2.4GHz band, instead of the 433MHz you asked for. It works well over 10 meters distance through 3 massive stone walls of a classic german house. And if it doesn’t - MySensors supports repeaters that can extend the range to multiple kilometres.

Another very important hint: Yes, you really do need that capacitor!

Bonus Post! Trying to link to interesting pages regarding the properties you are looking for:

definitely checkout mysensors. I have been using it for 2 years. Community there is very active. Lots of really cool projects, you can get some hardware that people have designed and 3dprint cases for sensors/modules too.