With the increase in popularity of Internet of Things (IoT) devices and their need to communicate wirelessly, there’s been a corresponding explosion of wireless protocols to chose from. Of course there’s Wi-Fi and Bluetooth, but for more specialized applications there are some other options like Z-Wave, LoRa, Sigfox, and Thread. There’s a decent amount of overlap in their capabilities too, so when [SHS] was investigating some low-cost Xiaomi sensors it was discovered that it is possible to convert them from their general purpose Bluetooth protocol over to the more IoT-specialized Zigbee protocol instead.
These combination temperature and humidity sensors have already been explored by [Aaron Christophel] who found that it’s possible to flash these devices with custom firmware. With that background, converting them from Bluetooth to Zigbee is not a huge leap. All that’s needed is the Zigbee firmware from [Ivan Belokobylskiy] aka [devbis] and to follow the steps put together by [SHS] which include a process for flashing the firmware using an over-the-air update and another using UART if the wireless updates go awry. Then it’s just a short process to pair the new Zigbee device to the network and the sensor is back up and running. 240 To 208 Transformer 3 Phase
Converting from one wireless protocol to another might not seem that necessary, but using Bluetooth as an IoT network often requires proxy nodes as support devices, whereas Zigbee can communicate directly from the sensor to a hub like Home Assistant. Other Zigbee devices themselves can also act as a mesh network of sorts without needing proxy nodes. The only downside of this upgrade is that once the Bluetooth firmware has been replaced, the devices no longer has any Bluetooth functionality.
Thanks to [RoganDawes] for the tip!
Remember when Wink promised one hub to rule them all? Curse you Sar….errrrr Will.i.am
Does anybody know about some similar gizmo but one which can measure humidity under 10% and with precision in hundredths?
unlikely. And certainly not cheap consumer product like this one. Even the best humidity sensors around like SHT45 don´t have this level of precision
If you´re measuring the humidity of a solid, i´d suggest to look in the direction of radar humidity meter (for wood / walls). Probably better <10% RH but still not what you wish.
I´m afraid that a device with such a precision will be a big, very expensive, calibrated instrument.
Precision in hundredths? Of a percent? I doubt you can buy sensors like that. If you want to build something yourself, I suggest looking at TI’s HDC3020. Among the cheap sensors it appears to be the most accurate.
Oh wait, I just checked my SCD30 code. The granularity of its measurements is 0.0015%RH. But I wouldn’t trust this part since its temperature sensor is accurate only in a very small region around its calibration point.
Just get some hair and a high-resolution rotary encoder. https://en.wikipedia.org/wiki/Hygrometer#Hair_tension_hygrometers
Consider the “Kestrel” brand of weather sensors if precision to 10ths is ok. I’ve had a handheld 3500 model for a year or so. Live at 8500′ and have seen very low wet bulb and RH values. So low that holding the sensor over my hand sees the values rise just from natural sweat/steam. I have no money or other interest in the company. It’s a fun toy(tool?) to show the kids just how fast conditions can change. Even engaging science – If my hand releases enough water vapor to change this sensor, can we calculate how much water vapor a treee releases?
I think they have ones that export via bluetooth and/or wifi as well.
I used to work for a firm on Long Island that makes dew point sensors & electronics that could measure dew point down to -100C or about 1PPM water vapor they are not cheap – http://www.phymetrix.com –
I already have mine swapped to the open firmware, but it’d be nice to not have to run proxy esp32s. I wonder how it affects battery life
The battery life is terrible. I flashed one and I get a little more than a week out of a battery. I’ve also had issues with upgrading firmware. I would hold off for a while.
Great! Finally a use for these things, just tried it and it pairs with my Tasmota (Sonoff) Zigbee brigde without problem.
mesh network will be great emergency network similar to airTag
There isn’t really anything wrong with Bluetooth. Except that I don’t have coverage with BT proxies in all my house. Zigbee mesh is available almost everywhere though. Great change for me. I wonder though how I will keep the firmware current from now on. :D
Zigbee protocol defines an ota firmware update method, as well. Hopefully they implemented that.
I’d prefer to be able to convert it to zwave, but that’s an entirely different radio length
“…whereas Zigbee can communicate directly from the sensor to a hub like Home Assistant.” This section makes little sense to me. If your Home Assistant is on an RPi like most, you can just use the built-in Bluetooth and get pretty good range from these sensors. If my RPi was in the middle of my house it would reach the whole house. You might fare even better with a fancier Bluetooth adaptor.
I get that some people have lots of Zigbee stuff so it’s already up and running for them, but surely Bluetooth is more convenient for most people?
https://github.com/pvvx/ATC_MiThermometer/issues/394
This is making me a little wary of the bluetooth setup. Although like a lot of things, some people are saying they have problems and some appear not to.
But posts above about battery life on zigbee are also concerning. Certainly the stock firmware leeched batteries.
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