Using a Xiaomi temperature sensor for presence?

presence

#1

I’m really liking the Xiaomi range of sensors. I have the motion, plug, and now temperature sensor. The temperature sensors are tiny and from what i can tell have great battery life. So the question:

Would it be possible to detect presence based on the heartbeat of one of these temp sensors. They are so small and cheap that they would make a great alternative to the smartthings presence keyfob, which i understand is a bit hit n miss?


(Mark) #2

I’m not sure that would work out the way you’re hoping. How often does that device wake up to send a temp update to the hub? My guess is not often enough to be useful as an arrival sensor.

I think the reason the battery life on the ST arrival sensors isn’t great is because it sends an “I’m here” signal every 30 seconds. But that means you don’t have to wait very long from the time you come into range of the hub to when the hub actually gets a message that you’ve arrived.

What exactly are your concerns with the ST presence device?


#3

Fair point. Looking at the recent events for the temp sensor device, the heartbeat is pretty random. At times its seconds apart, other times an hour could pass. I’m guessing its triggered by a change in temp\humidity as holding it in your hand immediately registers a change in the smartthings app.

The ST presence device is a bit pricey in my opinion, for something which may\may not do the job reliably. I’ve read through various posts discussing the presence sensors, and most issues seem to be around a lack of wired zigbee devices or repeaters (which i shouldn’t have a problem with) and\or battery life. I can understand that when the device is constantly pinging the hub its going to consume some power, but i cant justify having to replace the battery every few months.

I personally use the ST app to detect my presence, but i’m looking for a cheap, low maintenance device to give to the parents etc. From what I’ve read, short of using a smartphone, there aren’t really many options.


#4

You need a device with a very regular heartbeat at very short intervals, as well as one that will seamlessly reconnect to the network after it’s been out of range for a while. I don’t think that’s how the Xiaomi devices work. ( it’s not how most battery powered devices work, because it would use too much battery if the device has any other intended purpose besides check-in’s. )

As far as the SmartThings branded present sensor, it’s very subject to local conditions, particularly Wi-Fi interference. It’s not an amplified zigbee device. So it will work well for some people, and not for others.

There are a number of different ways of managing presence. The FAQ should be of interest:


(Eric) #5

I use an ST motion sensor in car for security. It would work for presence. Response is fairly quick, battery lasts at least a year. When you depart, then the sensor report would go inactive and may yet indicate your last motion until you return.

I use actual ST presence sensors wired to permanent power, for presence. A nearby repeater probably helps the reliability. I had set the departure delay to 7 minutes to cut out false departures, but It appears that ST silently revised my delay to about 2 minutes, and I’ve had no false departures for maybe 18months.


(Mark) #6

@docfx If battery is the major sticking point for you, take a look at what others have done to wire the presence sensor to an alternate power source. This does make it much less portable, but if putting it in the car of the person that you want to track their arrival is a reasonable option, then it could work.


#7

Thanks for all the replies guys.

I ended up going with the SharpTools + Tasker method. Its not as simple as handing someone a keyfob, but it is relatively easy to setup, is set and forget (no batteries to worry about), and seems to work reliably from what I’ve seen so far!