in iot ~ read.

Xiaomi Mijia MHO-C201

The thermometer was purchased few weeks before when I was reading about weather stations. I really liked the look. There are only reviews of this thermometer on web but none of tear-down, so I decided to write my own small review/tear-down.

I bought it, not so much  for measurements, as much as a designer thing for a home interior. The thought was immediately that this small thermometer would fit perfectly into the general chaos of dozens of magnets on the refrigerator. Thermometer is produced by Xiaomi, with the unpronounceable name "Xiaomi MiaoMiaoCe"According to the store, the following characteristics:

Model: MHO-C201
Screen: E-lnk (Wide viewing angle)
Temperature range: 0 ℃ ~ 60 ℃
Humidity measurement range: 0 ~ 100%
Accuracy: ± 0.3 ℃ and ± 3% RH
Power: CR-2032 (Button Battery about 1 year)

Sensirion’s new STS3x temperature sensor includes enhanced signal processing, two distinctive and user-selectable I2C addresses, and communication speeds of up to 1 MHz. The dual-flat no-leads (DFN) package has a footprint of 2.5 × 2.5 mm2 while retaining a height of 0.9 mm. This allows for easy integration of the STS3x series into various applications. Additionally, the wide supply voltage range of 2.15 to 5.5 V and low current consumption (1.7µA typical average current at 1 measurement per second) guarantees compatibility with a wide range of applications.

The image on the screen is really very clear, readable from any angle. It seems that it is drawn. Still e-ink looks better than conventional LCD screens. I showed the thermometer to several people, they were very surprised when they saw that the "painted" symbols on plastic suddenly change it looks very interesting. The thermometer screen displays two lines. At the top, the current temperature in Celsius (you can switch to Fahrenheit). In the bottom line, the current humidity in the room is displayed in percent and a small muzzle that displays comfort or not comfort conditions:

For people that are interested in internals here is image of main board

Internals

Main CPU inside is Holtek HT66F0182  16-pin NSOP package

This thermometer should not be considered an accurate instrument. This is more home-based, which should show what, at least roughly, is going on in your apartment, and at the same time it should attract attention or be a detail of the interior. In my case, the thermometer settled on the fridge, and judging by its appearance and colour, it fit there as a native. Now, at least I can approximately find out the temperature and humidity of the air in my apartment. Of course I would like that he still showed time, but it seems to me that this has at least increased the cost of the device, and reduced the autonomy.