House sensors using LoRa

I’m interested in converting my house sensor network into one running on LoRa.

The background to this is the sad demise of the Nottingham company WirelessThings from whom I had purchased a number of house sensors. These were small devices transmitting over 868MHz with a variety of ‘personalities’ including temperature, flood, magnetic, on/off, light and so on. I had them scattered around the home, including a water detector on my back fence where the seasonal flooding from the local river first enters my property.

The head end was a simple USB stick plugged into one of my SBCs running NodeRED. This collected incoming radio signals using a text protocol called ‘LLAP’ and converted them to MQTT, sending them on to a variety of end points such as alerting my mobile phone when floods were coming in. As the devices went into a configurable sleep mode, the button batteries lasted years without replacement. I even had a separate NodeRED flow that handled battery level to alert to replace batteries. They were useful in a number of ways:

  • knowledge of battery state
  • ability to ‘talk back’ to a sensor
  • transmission over relatively large distances
  • simple, configurable and multiple sensors using a small form factor enclosure
  • different sensors encoded values into a similar-length text string (12 bytes)

img_20161102_155134

All that has finished with the closing of that company, so I have been toying with using a LoRa gateway from someone like Pycom, or purchasing a full LoRa gateway and connecting this to The Things Network and thence back to my servers. Cost is playing a significant part as I can’t really afford three- or four-figure sums for my electronics hobby. The Pycom LoPy running MicroPython looks like a good alternative (even if it cannot act as a true LoRa gateway due to lack of multiple channels) so I may wait for that to stabilise and then work from there.

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