Ultracheap Wireless Environmental Monitoring

[Radian]

While there are plenty of wireless temperature/humidity displays to choose from, getting the data out of them for our own home integrations is always a challenge. And while they're not always too expensive, things soon add up if you want them in every room. Throw in slightly more sophisticated sensing like PM2.5 or CO² and the price skyrockets.

 

I have mentioned before how I use low-cost BTLE thermo-hygrometers with custom firmware to expose their data as BTLE beacons. Gathering the data from these beacons and dumping it onto the local network as MQTT is a perfect task for an ESP32. So while I was thinking about 3D printing an enclosure for the ESP I came across  this nifty little IKEA gadget that provides a PM2.5 air quality indicator in a rather nice looking desktop case:

 

XIAOMI Thermometer next to a couple of IKEA VINDRIKTNING 

 

The VINDRIKTNING (or 'wind direction' translated) has a USBC port round the back and three LEDs giving a crude 'traffic light' readout of air quality. People have already hacked these to extract the sensor data and relay it over WiFi  as MQTT for integration into Home Assistant or whatever. This struck me as an ideal 'base station' for my XIAOMIs while at the same time providing air quality data and anything else I could squeeze inside the box along with the ESP32.

 

ESP32-CAM wired to IKEA VINDRIKTNING PCB

 

ESP32 dev. boards tend to be a little bit bigger than ESP8266 so I had a job finding one that would fit. Oddly enough, the cheapest proved to be the ESP32-CAM which actually comes with a camera! As for getting more value out of the modification I also mounted a BME280 module on the ESP32 to provide temperature/humidity/barometric pressure as well as PM2.5 data from within the base station. Oh, and there's a light sensor that VINDRIKTNING uses to dim the LEDs so I fed that into an analogue input. There's also enough room in the box for a CO2 sensor but I've yet to wire that in. Unfortunately these additional sensor use some of the camera connections so a sneaky CCTV from this device wouldn't be possible when fully loaded with sensors.

 

CO2 sensor at the bottom left of the enclosure

 

The end result is a base station providing air quality measurements costing <£20 that can host numerous ~£6 thermometers.

So today we lightly browned some toast mid-morning and accidentally burnt flatbreads while making supper:

 

 

This base station is currently in the garden room, off the kitchen, next to a sliding patio door so the temperature swings quite a bit. However, In this position it picks up a thermometer about 20m away in the back garden, one inside the fridge and another in the kitchen. Those show up in different plots. Here is the barometric pressure and light level:

 

 

[SteamyTea]

I really need to get to grips with MQTT as I collect quite a bit of data.

Fitting a BMP280 is useful.

Just a shame that CurrentCost vanished as I like the Envi Opto I use to collect my energy data.

 

Not sure what has happened to a couple of your images, are they links to local storage?

[Radian]

29 minutes ago, SteamyTea said:

Not sure what has happened to a couple of your images, are they links to local storage?

Must have dropped them into post by mistake. Here they are.

 

XIAOMI Thermometer next to a couple of IKEA VINDRIKTNING

 

ESP32-CAM wired to IKEA VINDRIKTNING PCB

 

CO2 sensor at the bottom left of the enclosure

[SteamyTea]

15 minutes ago, Radian said:

CO2 sensor at the bottom left of the enclosure

I have a box of bits, including a CO₂, a Plantower particulate, numbeous BME/P280s and a few other bits.

Really must start cobbling them all together.

Kind of thing I have been keeping for when I break a leg and can't go out.

(I broke my pelvis a few years ago but could still drive, so that was not enough of an injury) 

Edited February 4, 2022 by SteamyTea

[Radian]

I know what you you mean about finding the time. Trouble is, when you're poorly, you're not always feeling like doing the sort of stuff you've put off doing.

 

BME280 temperature and humidity are handy but need calibrating. They're incidental to the corrections needed for the barometer so not fabulously accurate. I also got caught out by self heating. I thought the fact that VINDRIKTNING pulls air through with a small fan would improve the sampling but the ESP32 is drawing around 0.25W and this still bumps the temperature up a few degrees. Fortunately it's a pretty constant offset so easy to subtract.

[SteamyTea]

8 minutes ago, Radian said:

need calibrating

Sum off least squared against the calibration gauge for every temperature bin.

Or just use anomalies if absolute readings are not that important.

Good enough foe me.

 

Sun is out, so I am off out.