Wireless Doorbells to Home Assistant

Space Teams Electronics
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I have some wireless doorbells that operate at 433MHz. I would like to integrate them with Home Assistant, so I can get remote notifications that someone has pressed one of the buttons.

I have two potential plans for making this work (and am open to other plans!):

  1. Build a device around a microcontroller that listens to RF and sends the info to HA. Maybe scavenge the antenna from a receiver.
  2. Wire points in a receiver to GPIO pins on a microcontroller that sends the info to HA.

I’m comfortable with the microcontroller and HA parts, but not at all with RF. I’d kinda rather not wire directly into a receiver because there are 120V AC wires on that board.

It seems like there are multiple different standards used at 433MHz. This Overview | Radio FeatherWing | Adafruit Learning System page says:

All radios are sold individually and can only talk to radios of the same part number. E.g. RFM69 900 MHz can only talk to RFM69 900 MHz, LoRa 433 MHz can only talk to LoRa 433, etc.

Do we have something in the electronics lab that would let me figure out if this doorbell system uses either of those or something completely different?

I have an extra transmitter and receiver that I can look at part numbers on (they look like fairly simple boards), if that’s helpful, and am happy to sacrifice them to the project.

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Part numbers from those boards is where I’d start, always great when someone’s already done the work for us!

There are a couple of ways I could think to analyze it yourself. There are only a handful of protocols that consumer 433 mHz stuff uses, so if you can get a look at the signal you can probably find a match.

The only way I’ve tried in the past is to get a cheap little 433 module and sniff the frequency from an Arduino.

Failing that, I’ve seen people record the transmitted signal as audio (a low-tech SDR, I guess) and use an audio visualizer to inspect the timing.

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I picked up one of these a little while back but never got the home assistant add-in working to the point where it coughed up anything. I suspect trying the for-real software to figure out how it works before integrating with HA would yield better results, but I wound up just swapping out the sensors for something easier to integrate.

https://www.amazon.com/dp/B0CD7558GT