If not, then how can word it? If not possible to be on topic here, then where?

Tl;dr - how can I detect the presence of a Xiaomi Mi Band 3?

The full story:

As you can see from my question on h/w recommendations, I am trying to design an evacuation system for a chemical factory.

That requires knowing which room each employee is in at any given time. I can handle the system to track the employees, but have been looking for a long time for a durable wearable with long battery life for each employee to wear or carry.

  • I had considered Android 'phone, but they might be too expensive/bulky/fragile/short battery life.

  • A Raspberry Pi Zero W is cheap, but also quite large, needs a casing and I am unsure about battery life.

  • Passive RFID might not have the range, and active requires battery.

  • The AdaFruit Flora BLE looks interesting, but I can't find data about its battery life.

The I had an epiphany when I looked down and saw the cheap fitness tracker on my wrist. It's a Xiaomi Mi Band 3. I am charging it about once every 3 weeks, although I currently do not turn BT. I will need to calibrate that, although reviews give it 7 days of heavy usage, so it will be more than sufficient for a single day's use.

So - finally - to the question: would it be on topic to ask how I can detect transmission from the device?

If they are frequent enough (say, more than once per minute), then it doesn't matter what the signal is, so long as I can get a MAC address out of it and use that to locate the device.

  • 2
    Just ask the question, then I can answer it with a BLE beacon and a raspberry pi zero w as the receiver
    – hardillb
    Jan 6, 2019 at 23:35
  • Lolx! Hokey Cokey; feel free to post that as an answer
    – Mawg
    Jan 7, 2019 at 7:28
  • You can also answer iot.stackexchange.com/questions/3765/…
    – Mawg
    Jan 7, 2019 at 7:32

1 Answer 1


The question would be better with more generic phrasing, I think - as it stands, the reader is lead mistakenly to the specific brand/device.

Asking how to monitor a population of bluetooth devices (in any of the various possible states) seems perfectly in scope, and also brings in the meta/derrived sensing aspects of IoT.

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